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  • 1. Bestill onlineKjøp publikasjonen >>
    Bakhit, Babak
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Multifunctional transition metal diboride thin films grown by magnetron sputtering with metal-ion irradiation2020Licentiatavhandling, med artikler (Annet vitenskapelig)
    Delarbeid
    1. Controlling the B/Ti ratio of TiBx thin films grown by high-power impulse magnetron sputtering
    Åpne denne publikasjonen i ny fane eller vindu >>Controlling the B/Ti ratio of TiBx thin films grown by high-power impulse magnetron sputtering
    Vise andre…
    2018 (engelsk)Inngår i: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 36, nr 3, artikkel-id 030604Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    TiBx thin films grown from compound TiB2 targets by magnetron sputter deposition are typically highly over-stoichiometric, with x ranging from 3.5 to 2.4, due to differences in Ti and B preferential-ejection angles and gas-phase scattering during transport from the target to the substrate. Here, the authors demonstrate that stoichiometric TiB2 films can be obtained using highpower impulse magnetron sputtering (HiPIMS) operated in power-controlled mode. The B/Ti ratio x of films sputter-deposited in Ar is controllably varied from 2.08 to 1.83 by adjusting the length of HiPIMS pulses t(on) between 100 and 30 mu s, while maintaining average power and pulse frequency constant. This results in peak current densities J(T), peak ranging from 0.27 to 0.88 A/cm(2). Energy- and time-resolved mass spectrometry analyses of the ion fluxes incident at the substrate position show that the density of metal ions increases with decreasing t(on) due to a dramatic increase in J(T, peak) resulting in the strong gas rarefaction. With t(on)amp;lt;60 mu s (J(T),(peak)amp;gt; 0.4 A/cm(2)), film growth is increasingly controlled by ions incident at the substrate, rather than neutrals, as a result of the higher plasma dencity and, hence, electron-impact ionization probablity. Thus, since sputter- ejected Ti atoms have a higher probability of being ionized than B atoms, due to their lower first-ionization potential and larger ionization cross-section, the Ti concentration in as-deposited films increases with decreasing ton (increasing J(T,peak)) as ionized sputtered species are steered to the substrate by the plasma in order to maintain charge neutrality. Published by the AVS.

    sted, utgiver, år, opplag, sider
    A V S AMER INST PHYSICS, 2018
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-148101 (URN)10.1116/1.5026445 (DOI)000432372400013 ()
    Merknad

    Funding Agencies|Swedish Research Council VR [2014-5790, 642-2013-8020]; Knut and Alice Wallenberg foundation [KAW 2015.0043]; Aforsk foundation [16-359]; Carl Tryggers Stiftelse Contract [CTS 15:219, CTS 17:166, CTS 14:431]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO Mat LiU) [2009 00971]

    Tilgjengelig fra: 2018-05-30 Laget: 2018-05-30 Sist oppdatert: 2021-12-28
    2. Strategy for simultaneously increasing both hardness and toughness in ZrB2-rich Zr1-xTaxBy thin films
    Åpne denne publikasjonen i ny fane eller vindu >>Strategy for simultaneously increasing both hardness and toughness in ZrB2-rich Zr1-xTaxBy thin films
    Vise andre…
    2019 (engelsk)Inngår i: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 37, nr 3, artikkel-id 031506Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Refractory transition-metal diborides exhibit inherent hardness. However, this is not always sufficient to prevent failure in applications involving high mechanical and thermal stress, since hardness is typically accompanied by brittleness leading to crack formation and propagation. Toughness, the combination of hardness and ductility, is required to avoid brittle fracture. Here, the authors demonstrate a strategy for simultaneously enhancing both hardness and ductility of ZrB2-rich thin films grown in pure Ar on Al2O3(0001) and Si(001) substrates at 475 degrees C. ZrB2.4 layers are deposited by dc magnetron sputtering (DCMS) from a ZrB2 target, while Zr1-xTaxBy alloy films are grown, thus varying the B/metal ratio as a function of x, by adding pulsed high-power impulse magnetron sputtering (HiPIMS) from a Ta target to deposit Zr1-xTaxBy alloy films using hybrid Ta-HiPIMS/ZrB2-DCMS sputtering with a substrate bias synchronized to the metal-rich portion of each HiPIMS pulse. The average power P-Ta (and pulse frequency) applied to the HiPIMS Ta target is varied from 0 to 1800W (0 to 300 Hz) in increments of 600W (100 Hz). The resulting boron-to-metal ratio, y = B/(Zr+Ta), in as-deposited Zr1-xTaxBy films decreases from 2.4 to 1.5 as P-Ta is increased from 0 to 1800W, while x increases from 0 to 0.3. A combination of x-ray diffraction (XRD), glancing-angle XRD, transmission electron microscopy (TEM), analytical Z-contrast scanning TEM, electron energy-loss spectroscopy, energy-dispersive x-ray spectroscopy, x-ray photoelectron spectroscopy, and atom-probe tomography reveals that all films have the hexagonal AlB2 crystal structure with a columnar nanostructure, in which the column boundaries of layers with 0 amp;lt;= x amp;lt; 0.2 are B-rich, whereas those with x amp;gt;= 0.2 are Ta-rich. The nanostructural transition, combined with changes in average column widths, results in an similar to 20% increase in hardness, from 35 to 42 GPa, with a simultaneous increase of similar to 30% in nanoindentation toughness, from 4.0 to 5.2MPa root m. Published by the AVS.

    sted, utgiver, år, opplag, sider
    A V S AMER INST PHYSICS, 2019
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-159001 (URN)10.1116/1.5093170 (DOI)000472182400035 ()
    Merknad

    Funding Agencies|Swedish Research Council VR [2014-5790, 2018-03957, 642-2013-8020]; Knut and Alice Wallenbergs foundation [KAW 2015.0043]; VINNOVA [2018-04290]; Aforsk Foundation [16-359]; Carl Tryggers Stiftelse [CTS 15: 219, CTS 17: 166, CTS 14: 431]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO Mat LiU) [2009 00971]

    Tilgjengelig fra: 2019-07-19 Laget: 2019-07-19 Sist oppdatert: 2021-12-28
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  • 2.
    Bakhit, Babak
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Multifunctional Transition-metal Diboride Coatings Synthesized by Magnetron sputtering with Synchronized Metal-ion Irradiation2020Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Refractory transition-metal diborides (TMB2), classified as ultra-high temperature ceramics, are promising materials for extreme thermal and chemical environments. There is a growing demand for employing TMB2 in high-temperature electrodes, advanced nuclear fission reactors, molten metal containment, refractory crucibles, thermocouple protection tubes in steel baths and aluminum reduction cells, reinforcement fibers, solar power, aerospace, and armor applications. Magnetron-sputter-deposited TMB2 have recently received increasing attention as the next class of hard ceramic protective thin films. These layers usually crystallize in a hexagonal AlB2 crystal structure (P6/mmm, SG-191) in which B atoms form graphite-like honeycomb sheets between hexagonal-close-packed TM layers. The strong covalent bonding between TM and B atoms as well as within the honeycomb B sheets provides high melting temperature, hardness, and stiffness, while metallic bonding within TM layers results in good electrical and thermal conductivities. However, sputter-deposited TMB2 films suffer from several critical issues such as boron overstoichiometry, high brittleness, and low oxidation resistance. All of these aspects are addressed in the thesis.

    In Paper 1, the common issue with sputter-deposited diboride thin films, i.e. the presence of excess B, is resolved by using high power impulse magnetron sputtering (HiPIMS). The B/Ti ratio in TiBx films, used as a model materials system, is controllably varied from 2.08 to 1.83 by adjusting the HiPIMS pulse length ton, while maintaining the average power and pulse frequency constant. As a result, the peak current density increases from 0.27 to 0.88 A/cm2, which leads to an increased gas rarefaction and, hence, higher metal-ion densities in the plasma. Film growth becomes then increasingly controlled by ionized target atoms, rather than neutral species. Since sputter-ejected Ti atoms have a higher probability of being ionized than B atoms, due to their lower first-ionization potential and larger ionization cross-section, the B/Ti ratio in the films decreases a function of target peak current.

    While TM diborides are inherently hard, that alone is not sufficient to prevent failure in applications involving high stresses, as hardness is typically accompanied by brittleness. In order to avoid brittle cracking, thin films must be both hard and relatively ductile, which is referred to as high toughness. In Paper 2, it is demonstrated that Zr1-xTaxBy thin films grown by hybrid high-power impulse and DC magnetron co-sputtering (Ta-HiPIMS/ZrB2-DCMS) with x ≥ 0.2 are not only hard, but also tough. The films with x ≥ 0.2 show a self-organized columnar core/shell nanostructure (see Paper 3), in which crystalline hexagonal Zr-rich stoichiometric Zr1-xTaxB2 cores are surrounded by narrow dense, disordered Ta-rich shells that are B-deficient.

    The disordered shells have the structural characteristics of metallic-glass thin films, which exhibit both high strength and toughness. Hence, such a nanostructure combines the benefits of crystalline diboride nanocolumns, providing the high hardness, with the dense metallic-glasslike shells, which give rise to enhanced toughness.

    The mechanical properties of Zr1-xTaxBy thin films annealed in Ar atmosphere are studied as a function of annealing temperature Ta up to 1200 °C in Paper 4. In-situ and ex-situ nanoindentation analyses reveal that all films undergo age hardening up to Ta = 800 °C, with the highest hardness achieved for Zr0.8Ta0.2B1.8 (45.5±1.0 GPa). The age hardening, which occurs without any phase separation or decomposition, can be explained by point-defect recovery that enhances chemical bond density. Although hardness decreases at Ta > 800 °C due mainly to recrystallization, column coarsening, and planar defect annihilation, all layers show hardness values above 34 GPa over the entire Ta range.

    The oxidation resistance of TiBx thin films is addressed in Paper 5. In general, TMB2 suffer from rapid high-temperature oxidation, which is a critical issue for many applications. In this study, it is demonstrated that alloying the films with Al significantly increases the oxidation resistance with only a slight decrease in hardness. Contrary to bulk TiB2 synthesized by powder metallurgy processes, the oxidation products of TiB2 thin films do not contain the B2O3 oxide scale, which is usually observed below 1000 °C in air, and merely consists of a TiO2 phase. The enhanced oxidation resistance is attributed to the formation of a dense, protective Al-containing oxide scale, which considerably decreases the oxygen diffusion rate by suppressing the oxidecrystallites coarsening.

    To realize the goal of fully multifunctional diborides, Zr1-xCrxBy thin films grown by hybrid Cr-HiPIMS/ZrB2-DCMS co-sputtering are studied in Paper 6. These layers exhibit a unique combination of high hardness, toughness, wear, oxidation, and corrosion resistance.

    The last paper (Paper 7) addresses the issue of efficient energy and resource consumption in industrial processes, which United Nations defines as one of the sustainable development goals. The idea here is to replace the conventionally used thermal-energy flux from resistive heaters with the irradiation by high mass metal ions (Hf+), which results in more efficient energy transfer to the deposited layer. We deposited Ti0.67Hf0.33B1.7 films using hybrid HfB2-HiPIMS/TiB2-DCMS co-sputtering at substrate temperature not exceeding 100 °C. Results reveal that dense layers can be achieved with high hardness values (> 40 GPa) even though no external substrate heating was used during the process.

    Delarbeid
    1. Controlling the B/Ti ratio of TiBx thin films grown by high-power impulse magnetron sputtering
    Åpne denne publikasjonen i ny fane eller vindu >>Controlling the B/Ti ratio of TiBx thin films grown by high-power impulse magnetron sputtering
    Vise andre…
    2018 (engelsk)Inngår i: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 36, nr 3, artikkel-id 030604Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    TiBx thin films grown from compound TiB2 targets by magnetron sputter deposition are typically highly over-stoichiometric, with x ranging from 3.5 to 2.4, due to differences in Ti and B preferential-ejection angles and gas-phase scattering during transport from the target to the substrate. Here, the authors demonstrate that stoichiometric TiB2 films can be obtained using highpower impulse magnetron sputtering (HiPIMS) operated in power-controlled mode. The B/Ti ratio x of films sputter-deposited in Ar is controllably varied from 2.08 to 1.83 by adjusting the length of HiPIMS pulses t(on) between 100 and 30 mu s, while maintaining average power and pulse frequency constant. This results in peak current densities J(T), peak ranging from 0.27 to 0.88 A/cm(2). Energy- and time-resolved mass spectrometry analyses of the ion fluxes incident at the substrate position show that the density of metal ions increases with decreasing t(on) due to a dramatic increase in J(T, peak) resulting in the strong gas rarefaction. With t(on)amp;lt;60 mu s (J(T),(peak)amp;gt; 0.4 A/cm(2)), film growth is increasingly controlled by ions incident at the substrate, rather than neutrals, as a result of the higher plasma dencity and, hence, electron-impact ionization probablity. Thus, since sputter- ejected Ti atoms have a higher probability of being ionized than B atoms, due to their lower first-ionization potential and larger ionization cross-section, the Ti concentration in as-deposited films increases with decreasing ton (increasing J(T,peak)) as ionized sputtered species are steered to the substrate by the plasma in order to maintain charge neutrality. Published by the AVS.

    sted, utgiver, år, opplag, sider
    A V S AMER INST PHYSICS, 2018
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-148101 (URN)10.1116/1.5026445 (DOI)000432372400013 ()
    Merknad

    Funding Agencies|Swedish Research Council VR [2014-5790, 642-2013-8020]; Knut and Alice Wallenberg foundation [KAW 2015.0043]; Aforsk foundation [16-359]; Carl Tryggers Stiftelse Contract [CTS 15:219, CTS 17:166, CTS 14:431]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO Mat LiU) [2009 00971]

    Tilgjengelig fra: 2018-05-30 Laget: 2018-05-30 Sist oppdatert: 2021-12-28
    2. Strategy for simultaneously increasing both hardness and toughness in ZrB2-rich Zr1-xTaxBy thin films
    Åpne denne publikasjonen i ny fane eller vindu >>Strategy for simultaneously increasing both hardness and toughness in ZrB2-rich Zr1-xTaxBy thin films
    Vise andre…
    2019 (engelsk)Inngår i: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 37, nr 3, artikkel-id 031506Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Refractory transition-metal diborides exhibit inherent hardness. However, this is not always sufficient to prevent failure in applications involving high mechanical and thermal stress, since hardness is typically accompanied by brittleness leading to crack formation and propagation. Toughness, the combination of hardness and ductility, is required to avoid brittle fracture. Here, the authors demonstrate a strategy for simultaneously enhancing both hardness and ductility of ZrB2-rich thin films grown in pure Ar on Al2O3(0001) and Si(001) substrates at 475 degrees C. ZrB2.4 layers are deposited by dc magnetron sputtering (DCMS) from a ZrB2 target, while Zr1-xTaxBy alloy films are grown, thus varying the B/metal ratio as a function of x, by adding pulsed high-power impulse magnetron sputtering (HiPIMS) from a Ta target to deposit Zr1-xTaxBy alloy films using hybrid Ta-HiPIMS/ZrB2-DCMS sputtering with a substrate bias synchronized to the metal-rich portion of each HiPIMS pulse. The average power P-Ta (and pulse frequency) applied to the HiPIMS Ta target is varied from 0 to 1800W (0 to 300 Hz) in increments of 600W (100 Hz). The resulting boron-to-metal ratio, y = B/(Zr+Ta), in as-deposited Zr1-xTaxBy films decreases from 2.4 to 1.5 as P-Ta is increased from 0 to 1800W, while x increases from 0 to 0.3. A combination of x-ray diffraction (XRD), glancing-angle XRD, transmission electron microscopy (TEM), analytical Z-contrast scanning TEM, electron energy-loss spectroscopy, energy-dispersive x-ray spectroscopy, x-ray photoelectron spectroscopy, and atom-probe tomography reveals that all films have the hexagonal AlB2 crystal structure with a columnar nanostructure, in which the column boundaries of layers with 0 amp;lt;= x amp;lt; 0.2 are B-rich, whereas those with x amp;gt;= 0.2 are Ta-rich. The nanostructural transition, combined with changes in average column widths, results in an similar to 20% increase in hardness, from 35 to 42 GPa, with a simultaneous increase of similar to 30% in nanoindentation toughness, from 4.0 to 5.2MPa root m. Published by the AVS.

    sted, utgiver, år, opplag, sider
    A V S AMER INST PHYSICS, 2019
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-159001 (URN)10.1116/1.5093170 (DOI)000472182400035 ()
    Merknad

    Funding Agencies|Swedish Research Council VR [2014-5790, 2018-03957, 642-2013-8020]; Knut and Alice Wallenbergs foundation [KAW 2015.0043]; VINNOVA [2018-04290]; Aforsk Foundation [16-359]; Carl Tryggers Stiftelse [CTS 15: 219, CTS 17: 166, CTS 14: 431]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO Mat LiU) [2009 00971]

    Tilgjengelig fra: 2019-07-19 Laget: 2019-07-19 Sist oppdatert: 2021-12-28
    3. Self-organized columnar Zr0.7Ta0.3B1.5 core/shell-nanostructure thin films
    Åpne denne publikasjonen i ny fane eller vindu >>Self-organized columnar Zr0.7Ta0.3B1.5 core/shell-nanostructure thin films
    Vise andre…
    2020 (engelsk)Inngår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 401, artikkel-id 126237Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    We recently showed that Zr1−xTaxBy thin films have columnar nanostructure in which column boundaries are B-rich for x < 0.2, while Ta-rich for x ≥ 0.2. Layers with x ≥ 0.2 exhibit higher hardness and, simultaneously, enhanced toughness. Here, we determine the atomic-scale nanostructure of sputter-deposited columnar Zr0.7Ta0.3B1.5 thin films. The columns, 95 ± 17 Å, are core/shell nanostructures in which 80 ± 15-Å cores are crystalline hexagonal-AlB2-structure Zr-rich stoichiometric Zr1−xTaxB2. The shell structure is a narrow dense, disordered region that is Ta-rich and highly B-deficient. The cores are formed under intense ion mixing via preferential Ta segregation, due to the lower formation enthalpy of TaB2 than ZrB2, in response to the chemical driving force to form a stoichiometric compound. The films with unique combination of nanosized crystalline cores and dense metallic-glass-like shells provide excellent mechanical properties.

    sted, utgiver, år, opplag, sider
    Elsevier, 2020
    Emneord
    Thin films, Transition-metal (TM) diborides, Self-organized, Core/shell nanostructure, Hardness and toughness
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-169201 (URN)10.1016/j.surfcoat.2020.126237 (DOI)000583161500008 ()2-s2.0-85089079938 (Scopus ID)
    Merknad

    Funding agencies:  Knut and Alice Wallenberg (KAW) FoundationKnut & Alice Wallenberg Foundation [KAW 2015.0043]; electron microscopy laboratory in Linkoping; Swedish Research Council VRSwedish Research Council [2014-5790, 2018-03957, 2019-05403, 642-2013-8020]; VINNOVA Gran

    Tilgjengelig fra: 2020-09-11 Laget: 2020-09-11 Sist oppdatert: 2021-12-28bibliografisk kontrollert
    4. Age hardening in superhard ZrB2-rich Zr1-xTaxBy thin films
    Åpne denne publikasjonen i ny fane eller vindu >>Age hardening in superhard ZrB2-rich Zr1-xTaxBy thin films
    Vise andre…
    2021 (engelsk)Inngår i: Scripta Materialia, ISSN 1359-6462, E-ISSN 1872-8456, Vol. 191, s. 120-125Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    We recently showed that sputter-deposited Zr1-xTaxBy thin films have hexagonal AlB2-type columnar nanostructure in which column boundaries are B-rich for x < 0.2, while Ta-rich for x ≥ 0.2. As-deposited layers with x ≥ 0.2 exhibit higher hardness and, simultaneously, enhanced toughness. Here, we study the mechanical properties of ZrB2.4, Zr0.8Ta0.2B1.8, and Zr0.7Ta0.3B1.5 films annealed in Ar atmosphere as a function of annealing temperature Ta up to 1200 °C. In-situ and ex-situ nanoindentation analyses reveal that all films undergo age hardening up to Ta = 800 °C, with the highest hardness achieved for Zr0.8Ta0.2B1.8 (45.5±1.0 GPa). The age hardening, which occurs without any phase separation or decomposition, can be explained by point-defect recovery that enhances chemical bond density. Although hardness decreases at Ta > 800 °C due mainly to recrystallization, column coarsening, and planar defect annihilation, all layers show hardness values above 34 GPa over the entire Ta range.

    sted, utgiver, år, opplag, sider
    Elsevier, 2021
    Emneord
    Thin films; Transition-metal (TM) diboridesAge hardening; Thermal stability; Hardness and elastic modulus
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-170224 (URN)10.1016/j.scriptamat.2020.09.026 (DOI)urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-170224 ()2-s2.0-85091672167 (Scopus ID)
    Tilgjengelig fra: 2020-10-02 Laget: 2020-10-02 Sist oppdatert: 2024-02-01bibliografisk kontrollert
    5. Improving the high-temperature oxidation resistance of TiB2 thin films by alloying with Al
    Åpne denne publikasjonen i ny fane eller vindu >>Improving the high-temperature oxidation resistance of TiB2 thin films by alloying with Al
    Vise andre…
    2020 (engelsk)Inngår i: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 196, s. 677-689Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Refractory transition-metal diborides (TMB2) are candidates for extreme environments due to melting points above 3000 degrees C, excellent hardness, good chemical stability, and thermal and electrical conductivity. However, they typically suffer from rapid high-temperature oxidation. Here, we study the effect of Al addition on the oxidation properties of sputter-deposited TiB2-rich Ti1-xAlxBy thin films and demonstrate that alloying the films with Al significantly increases the oxidation resistance with a slight decrease in hardness. TiB2.4 layers are deposited by dc magnetron sputtering (DCMS) from a TiB2 target, while Ti1-xAlxBy alloy films are grown by hybrid high-power impulse and dc magnetron co-sputtering (Al-HiPIMS/TiB2-DCMS). All as-deposited films exhibit columnar structure. The column boundaries of TiB2.4 are B-rich, while Ti0.68Al0.32B1.35 alloys have Ti-rich columns surrounded by a Ti(1-x)Al(x)By tissue phase which is predominantly Al rich. Air-annealing TiB2.4 at temperatures above 500 degrees C leads to the formation of oxide scales that do not contain B and mostly consist of a rutile-TiO2 (s) phase. The resulting oxidation products are highly porous due to the evaporation of B2O3 (g) phase as well as the coarsening of TiO2 crystallites. This poor oxidation resistance is significantly improved by alloying with Al. While air-annealing at 800 degrees C for 0.5 h results in the formation of an similar to 1900-nm oxide scale on TiB2.4, the thickness of the scale formed on the Ti0.68Al0.32B1.35 alloys is similar to 470 nm. The enhanced oxidation resistance is attributed to the formation of a dense, protective Al-containing oxide scale that considerably decreases the oxygen diffusion rate by suppressing the oxide-crystallites coarsening. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

    sted, utgiver, år, opplag, sider
    PERGAMON-ELSEVIER SCIENCE LTD, 2020
    Emneord
    Thin films; Titanium diboride (TiB2); Nanostructure; XPS; High temperature oxidation
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-168859 (URN)10.1016/j.actamat.2020.07.025 (DOI)000557651000060 ()
    Merknad

    Funding Agencies|Knut and Alice Wallenberg (KAW) foundationKnut & Alice Wallenberg Foundation [KAW 2015.0043]; Swedish Research Council VR Grant [2014-5790, 2018-03957, 642-2013-8020]; VINNOVAVinnova [2018-04290]; Aforsk foundation [16-359]; Carl Tryggers Stiftelse [CTS 15:219, CTS 17:166, CTS 14:431]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO Mat LiU) [2009 00971]; Swedish research council VR-RFISwedish Research Council [2017-00646_9]; Swedish Foundation for Strategic ResearchSwedish Foundation for Strategic Research [RIF14-0053, RIF14-0074]

    Tilgjengelig fra: 2020-09-11 Laget: 2020-09-11 Sist oppdatert: 2021-12-29
    6. Multifunctional ZrB2-rich Zr1-xCrxBy thin films with enhanced mechanical, oxidation, and corrosion properties
    Åpne denne publikasjonen i ny fane eller vindu >>Multifunctional ZrB2-rich Zr1-xCrxBy thin films with enhanced mechanical, oxidation, and corrosion properties
    Vise andre…
    2021 (engelsk)Inngår i: Vacuum, ISSN 0042-207X, E-ISSN 1879-2715, Vol. 185, artikkel-id 109990Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Refractory transition-metal (TM) diborides have high melting points, excellent hardness, and good  chemical  stability.  However, these properties are not sufficient for applications involving extreme  environments that require high mechanical strength as well as oxidation and corrosion resistance. Here, we study the effect of Cr addition on the properties of ZrB2-rich Zr1-xCrxBy thin films grown by hybrid high-power impulse and dc magnetron co-sputtering (Cr-HiPIMS/ZrB2-DCMS) with a 100-V Cr-metal-ion synchronized potential. Cr metal fraction, x = Cr/(Zr+Cr), is increased from 0.23 to 0.44 by decreasing the power Pzrb2 applied to the DCMS ZrB2 target from 4000 to 2000 W, while the average power, pulse width, and frequency applied to the HiPIMS Cr target are maintained constant. In addition, y decreases from 2.18 to 1.11 as a function of Pzrb2, as a result of supplying Cr to the growing film and preferential B resputtering caused by the pulsed Cr-ion flux. ZrB2.18, Zr0.77Cr0.23B1.52, Zr0.71Cr0.29B1.42, and Zr0.68Cr0.32B1.38 2 films have hexagonal AlB2 crystal structure with a columnar nanostructure, while Zr0.64Cr0.36B1.30 and Zr0.56Cr0.44B1.11 are  amorphous. All films show hardness above 30 GPa. Zr0.56Cr0.44B1.11 alloys exhibit much better toughness, wear, oxidation, and corrosion resistance than ZrB2.18. This combination of properties   makes Zr0.56Cr0.44B1.11 ideal candidates for numerous strategic applications.

    Emneord
    Thin films, Transition-metal (TM) diborides, Mechanical properties, Wear, Oxidation, Corrosion
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-171888 (URN)10.1016/j.vacuum.2020.109990 (DOI)000618239100003 ()
    Merknad

    Funding agencies: We acknowledge support from the Knut and Alice Wallenberg (KAW) foundation for Project funding (KAW 2015.0043). Financial support from the Swedish Research Council VR Grant 2018–03957 and 642-2013-8020, the VINNOVA Grant 2019–04882, and Carl Tryggers Stiftelse contracts CTS 15:219, CTS 17:166, and CTS 14:431 are also gratefully acknowledged. Furthermore, the authors acknowledge financial support from the Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linköping University (Faculty Grant SFO Mat LiU No. 2009 00971). Supports from the Swedish research council VR-RFI (#2017–00646_9) for the Accelerator based ion-technological center and from the Swedish Foundation for Strategic Research (contract RIF14-0053; for the tandem accelerator laboratory in Uppsala University, and contract RIF14-0074; for the electron microscopy laboratory) are acknowledged.

    Tilgjengelig fra: 2020-12-11 Laget: 2020-12-11 Sist oppdatert: 2021-12-28
    7. Dense Ti0.67Hf0.33B1.7 thin films grown by hybrid HfB2-HiPIMS/TiB2-DCMS co-sputtering without external heating
    Åpne denne publikasjonen i ny fane eller vindu >>Dense Ti0.67Hf0.33B1.7 thin films grown by hybrid HfB2-HiPIMS/TiB2-DCMS co-sputtering without external heating
    Vise andre…
    2021 (engelsk)Inngår i: Vacuum, ISSN 0042-207X, E-ISSN 1879-2715, Vol. 186, artikkel-id 110057Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    There is a need for developing synthesis techniques that allow the growth of high-quality functional films at low substrate temperatures to minimize energy consumption and enable coating temperature-sensitive substrates. A typical shortcoming of conventional low-temperature growth strategies is insufficient atomic mobility, which leads to porous microstructures with impurity incorporation due to atmosphere exposure, and, in turn, poor mechanical properties. Here, we report the synthesis of dense Ti0.67Hf0.33B1.7 thin films with a hardness of ∼41.0 GPa grown without external heating (substrate temperature below ∼100 °C) by hybrid high-power impulse and dc magnetron co-sputtering (HfB2-HiPIMS/TiB2-DCMS) in pure Ar on Al2O3(0001) substrates. A substrate bias potential of −300 V is synchronized to the target-ion-rich portion of each HiPIMS pulse. The limited atomic mobility inherent to such desired low-temperature deposition is compensated for by heavy-mass ion (Hf+) irradiation promoting the growth of dense Ti0.67Hf0.33B1.7.

    sted, utgiver, år, opplag, sider
    Elsevier, 2021
    Emneord
    Thin films, Borides, Low-temperature sputter deposition, Hybrid HiPIMS/DCMS, Hardness
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-172653 (URN)10.1016/j.vacuum.2021.110057 (DOI)000620647100008 ()
    Forskningsfinansiär
    Knut and Alice Wallenberg Foundation, KAW 2015.0043Swedish Research Council, 2018-03957, 642-2013-8020Vinnova, 2019-04882Swedish Energy Agency, 51201-1Carl Tryggers foundation , CTS 15:219, CTS 17:166, CTS 14:431Linköpings universitet, 2009 00971Swedish Research Council, #2017-00646_9Swedish Foundation for Strategic Research , RIF14-0053, RIF14-0074
    Merknad

    Additional funding agencies: German Science Foundation (DFG) : SCHN735/42-1.

    Tilgjengelig fra: 2021-01-15 Laget: 2021-01-15 Sist oppdatert: 2021-12-28bibliografisk kontrollert
  • 3.
    Bakhit, Babak
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. Univ Cambridge, England; Univ Cambridge, England.
    Oxidation properties of quaternary Zr-based diboride thin films grown by hybrid high-power impulse/DC magnetron co-sputtering2024Inngår i: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 42, nr 1, artikkel-id 010401Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    Sputter-deposited transition metal diborides are subject of increasing attention for protective hard coatings. However, they suffer from high brittleness and rapid oxidation. Alloying with Ta increases their toughness, but their oxidation resistance requires further enhancement. Here, the influence of adding Si on the microstructure, mechanical, and oxidation properties of quaternary Zr1-(x + y)TaxSiyBz thin films grown by hybrid high-power impulse/DC magnetron co-sputtering (ZrB2-DCMS/Ta-HiPIMS/Si-DCMS) is studied. The layers are deposited at two different conditions of Ta-target HiPIMS powers and frequencies (30 W/100 Hz and 60 W/200 Hz series) with Si-target DCMS powers P-Si = 0, 10, 15, and 20 W, while the ZrB2-target DCMS power is maintained constant at 200 W. For the 30 W/100 Hz series, x decreases from 0.20 to 0.15, y increases from 0 to 0.22, and z decreases from 2.0 to 1.8 by increasing P-Si. The Ta/metal ratio remains constant at x = 0.3 for the 60 W/200 Hz series, while y increases from 0 to 0.1, and z decreases from 1.7 to 1.4. All layers show columnar growth and crystallize in a hexagonal-diboride structure, but crystal orientations change by increasing P-Si. The 60 W/200 Hz series have much denser microstructure than the 30 W/100 Hz series. The 60 W/200 Hz series have high hardness values (&gt;= 35 GPa), while the hardness of the 30 W/100 Hz series significantly decreases from similar to 37 to similar to 21 GPa as a function of P-Si. Zr0.7Ta0.3B1.7 has markedly better high-temperature oxidation resistance than Zr0.8Ta0.2B2.0 due to the formation of protective B-containing oxide scales. Alloying with Si considerably decreases the oxidation rate of the 30 W/100 Hz series owing to the formation of oxide scales containing a ZrSiO4 phase with a thin Si oxide top layer; however, the oxidation rate increases for the 60 W/200 Hz series as these quaternary alloys do not contain sufficiently high B and Si to form oxidation protective barriers.

  • 4.
    Bakhit, Babak
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Dorri, Samira
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Kooijman, Agnieszka
    Department of Materials Science and Engineering, Delft University of Technology, Delft, the Netherlands.
    Wu, Zhengtao
    School of Electromechanical Engineering, Guangdong University of Technology, Guangzhou, China.
    Lu, Jun
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Rosén, Johanna
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Mol, Johannes M.C.
    Department of Materials Science and Engineering, Delft University of Technology, Delft, the Netherlands.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Petrov, Ivan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. Materials Research Laboratory and Department of Materials Science, University of Illinois, Urbana, IL, USA; Department of Materials Science and Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan .
    Greene, Joseph E
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. Materials Research Laboratory and Department of Materials Science, University of Illinois, Urbana, IL, USA; Department of Materials Science and Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan .
    Greczynski, Grzegorz
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Multifunctional ZrB2-rich Zr1-xCrxBy thin films with enhanced mechanical, oxidation, and corrosion properties2021Inngår i: Vacuum, ISSN 0042-207X, E-ISSN 1879-2715, Vol. 185, artikkel-id 109990Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Refractory transition-metal (TM) diborides have high melting points, excellent hardness, and good  chemical  stability.  However, these properties are not sufficient for applications involving extreme  environments that require high mechanical strength as well as oxidation and corrosion resistance. Here, we study the effect of Cr addition on the properties of ZrB2-rich Zr1-xCrxBy thin films grown by hybrid high-power impulse and dc magnetron co-sputtering (Cr-HiPIMS/ZrB2-DCMS) with a 100-V Cr-metal-ion synchronized potential. Cr metal fraction, x = Cr/(Zr+Cr), is increased from 0.23 to 0.44 by decreasing the power Pzrb2 applied to the DCMS ZrB2 target from 4000 to 2000 W, while the average power, pulse width, and frequency applied to the HiPIMS Cr target are maintained constant. In addition, y decreases from 2.18 to 1.11 as a function of Pzrb2, as a result of supplying Cr to the growing film and preferential B resputtering caused by the pulsed Cr-ion flux. ZrB2.18, Zr0.77Cr0.23B1.52, Zr0.71Cr0.29B1.42, and Zr0.68Cr0.32B1.38 2 films have hexagonal AlB2 crystal structure with a columnar nanostructure, while Zr0.64Cr0.36B1.30 and Zr0.56Cr0.44B1.11 are  amorphous. All films show hardness above 30 GPa. Zr0.56Cr0.44B1.11 alloys exhibit much better toughness, wear, oxidation, and corrosion resistance than ZrB2.18. This combination of properties   makes Zr0.56Cr0.44B1.11 ideal candidates for numerous strategic applications.

    Fulltekst (pdf)
    fulltext
  • 5.
    Bakhit, Babak
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Dorri, Samira
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Kosari, Ali
    Delft Univ Technol, Netherlands.
    Mol, Arjan
    Delft Univ Technol, Netherlands.
    Petrov, Ivan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. Univ Illinois, IL 61801 USA; Natl Taiwan Univ Sci & Technol, Taiwan.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Greczynski, Grzegorz
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Microstructure, mechanical, and corrosion properties of Zr1-xCrxBy diboride alloy thin films grown by hybrid high power impulse/DC magnetron co-sputtering2022Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 591, artikkel-id 153164Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We study microstructure, mechanical, and corrosion properties of Zr1-xCrxBy coatings deposited by hybrid high power impulse/DC magnetron co-sputtering (CrB2-HiPIMS/ZrB2-DCMS). Cr/(Zr + Cr) ratio, x, increases from 0.13 to 0.9, while B/(Zr + Cr) ratio, y, decreases from 2.92 to 1.81. As reference, ZrB2.18 and CrB1.81 layers are grown at 4000 W DCMS. ZrB2.18 and CrB1.81 columns are continual from near substrate toward the surface with open column boundaries. We find that the critical growth parameter to achieve dense films is the ratio of Cr+- dominated ion flux and the (Zr + B) neutral flux from the ZrB2 target. Thus, the alloys are categorized in two groups: films with x &lt; 0.32 (low Cr+/(Zr + B) ratios) that have continuous columnar growth, rough surfaces, and open column boundaries, and films with x &gt;= 0.32 (high Cr+/(Zr + B) ratios) that Cr+-dominated ion fluxes are sufficient to interrupt continuous columns, resulting in smooth surface and dense fine-grain microstructure. The pulsed metal-ion irradiation is more effective in film densification than continuous Ar+ bombardment. Dense Zr0.46Cr0.54B2.40 and Zr0.10Cr0.90B1.81 alloys are hard (&gt; 30 GPa) and almost stress-free with relative nano indentation toughness of 1.3 MPa root m and 2.3 MPa root m, respectively, and remarkedly low corrosion rates (~& nbsp;1.0 x 10(-6) mA/cm(2) for Zr0.46Cr0.54B2.40 and~& nbsp; 2.1 x 10(-6) mA/cm(2) for Zr0.10Cr0.90B1.81).

    Fulltekst (pdf)
    fulltext
  • 6.
    Bakhit, Babak
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Engberg, David
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Lu, Jun
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Rosén, Johanna
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Högberg, Hans
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Petrov, Ivan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. Univ Illinois, IL 61801 USA.
    Greene, Joseph E
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. Univ Illinois, IL 61801 USA.
    Greczynski, Grzegorz
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Strategy for simultaneously increasing both hardness and toughness in ZrB2-rich Zr1-xTaxBy thin films2019Inngår i: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 37, nr 3, artikkel-id 031506Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Refractory transition-metal diborides exhibit inherent hardness. However, this is not always sufficient to prevent failure in applications involving high mechanical and thermal stress, since hardness is typically accompanied by brittleness leading to crack formation and propagation. Toughness, the combination of hardness and ductility, is required to avoid brittle fracture. Here, the authors demonstrate a strategy for simultaneously enhancing both hardness and ductility of ZrB2-rich thin films grown in pure Ar on Al2O3(0001) and Si(001) substrates at 475 degrees C. ZrB2.4 layers are deposited by dc magnetron sputtering (DCMS) from a ZrB2 target, while Zr1-xTaxBy alloy films are grown, thus varying the B/metal ratio as a function of x, by adding pulsed high-power impulse magnetron sputtering (HiPIMS) from a Ta target to deposit Zr1-xTaxBy alloy films using hybrid Ta-HiPIMS/ZrB2-DCMS sputtering with a substrate bias synchronized to the metal-rich portion of each HiPIMS pulse. The average power P-Ta (and pulse frequency) applied to the HiPIMS Ta target is varied from 0 to 1800W (0 to 300 Hz) in increments of 600W (100 Hz). The resulting boron-to-metal ratio, y = B/(Zr+Ta), in as-deposited Zr1-xTaxBy films decreases from 2.4 to 1.5 as P-Ta is increased from 0 to 1800W, while x increases from 0 to 0.3. A combination of x-ray diffraction (XRD), glancing-angle XRD, transmission electron microscopy (TEM), analytical Z-contrast scanning TEM, electron energy-loss spectroscopy, energy-dispersive x-ray spectroscopy, x-ray photoelectron spectroscopy, and atom-probe tomography reveals that all films have the hexagonal AlB2 crystal structure with a columnar nanostructure, in which the column boundaries of layers with 0 amp;lt;= x amp;lt; 0.2 are B-rich, whereas those with x amp;gt;= 0.2 are Ta-rich. The nanostructural transition, combined with changes in average column widths, results in an similar to 20% increase in hardness, from 35 to 42 GPa, with a simultaneous increase of similar to 30% in nanoindentation toughness, from 4.0 to 5.2MPa root m. Published by the AVS.

    Fulltekst (pdf)
    fulltext
  • 7.
    Bakhit, Babak
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Mráz, Stanislav
    Materials Chemistry, RWTH Aachen University, Aachen, Germany.
    Lu, Jun
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Rosén, Johanna
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Schneider, Jochen M.
    Materials Chemistry, RWTH Aachen University, Aachen, Germany.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Petrov, Ivan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. Materials Research Laboratory and Department of Materials Science, University of Illinois, Urbana, IL, USA; Department of Materials Science and Engineering, National Taiwan University of Science and Technology, Taipei, Taiwan.
    Greczynski, Grzegorz
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Dense Ti0.67Hf0.33B1.7 thin films grown by hybrid HfB2-HiPIMS/TiB2-DCMS co-sputtering without external heating2021Inngår i: Vacuum, ISSN 0042-207X, E-ISSN 1879-2715, Vol. 186, artikkel-id 110057Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    There is a need for developing synthesis techniques that allow the growth of high-quality functional films at low substrate temperatures to minimize energy consumption and enable coating temperature-sensitive substrates. A typical shortcoming of conventional low-temperature growth strategies is insufficient atomic mobility, which leads to porous microstructures with impurity incorporation due to atmosphere exposure, and, in turn, poor mechanical properties. Here, we report the synthesis of dense Ti0.67Hf0.33B1.7 thin films with a hardness of ∼41.0 GPa grown without external heating (substrate temperature below ∼100 °C) by hybrid high-power impulse and dc magnetron co-sputtering (HfB2-HiPIMS/TiB2-DCMS) in pure Ar on Al2O3(0001) substrates. A substrate bias potential of −300 V is synchronized to the target-ion-rich portion of each HiPIMS pulse. The limited atomic mobility inherent to such desired low-temperature deposition is compensated for by heavy-mass ion (Hf+) irradiation promoting the growth of dense Ti0.67Hf0.33B1.7.

    Fulltekst (pdf)
    fulltext
  • 8.
    Bakhit, Babak
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Palisaitis, Justinas
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Persson, Per O.Å.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Alling, Björn
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Rosen, Johanna
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Petrov, Ivan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. Materials Research Laboratory and Department of Materials Science, University of Illinois, Urbana IL 61801, USA; Department of Materials Science and Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan.
    Greene, Joseph E
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. Materials Research Laboratory and Department of Materials Science, University of Illinois, Urbana IL 61801, USA; Department of Materials Science and Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan.
    Greczynski, Grzegorz
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Self-organized columnar Zr0.7Ta0.3B1.5 core/shell-nanostructure thin films2020Inngår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 401, artikkel-id 126237Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We recently showed that Zr1−xTaxBy thin films have columnar nanostructure in which column boundaries are B-rich for x < 0.2, while Ta-rich for x ≥ 0.2. Layers with x ≥ 0.2 exhibit higher hardness and, simultaneously, enhanced toughness. Here, we determine the atomic-scale nanostructure of sputter-deposited columnar Zr0.7Ta0.3B1.5 thin films. The columns, 95 ± 17 Å, are core/shell nanostructures in which 80 ± 15-Å cores are crystalline hexagonal-AlB2-structure Zr-rich stoichiometric Zr1−xTaxB2. The shell structure is a narrow dense, disordered region that is Ta-rich and highly B-deficient. The cores are formed under intense ion mixing via preferential Ta segregation, due to the lower formation enthalpy of TaB2 than ZrB2, in response to the chemical driving force to form a stoichiometric compound. The films with unique combination of nanosized crystalline cores and dense metallic-glass-like shells provide excellent mechanical properties.

    Fulltekst (pdf)
    fulltext
  • 9.
    Bakhit, Babak
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Palisaitis, Justinas
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Thörnberg, Jimmy
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Rosén, Johanna
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Persson, Per O A
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Petrov, Ivan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. Univ Illinois, IL 61801 USA; Natl Taiwan Univ Sci & Technol, Taiwan.
    Greene, Joseph E
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. Univ Illinois, IL 61801 USA; Natl Taiwan Univ Sci & Technol, Taiwan.
    Greczynski, Grzegorz
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Improving the high-temperature oxidation resistance of TiB2 thin films by alloying with Al2020Inngår i: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 196, s. 677-689Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Refractory transition-metal diborides (TMB2) are candidates for extreme environments due to melting points above 3000 degrees C, excellent hardness, good chemical stability, and thermal and electrical conductivity. However, they typically suffer from rapid high-temperature oxidation. Here, we study the effect of Al addition on the oxidation properties of sputter-deposited TiB2-rich Ti1-xAlxBy thin films and demonstrate that alloying the films with Al significantly increases the oxidation resistance with a slight decrease in hardness. TiB2.4 layers are deposited by dc magnetron sputtering (DCMS) from a TiB2 target, while Ti1-xAlxBy alloy films are grown by hybrid high-power impulse and dc magnetron co-sputtering (Al-HiPIMS/TiB2-DCMS). All as-deposited films exhibit columnar structure. The column boundaries of TiB2.4 are B-rich, while Ti0.68Al0.32B1.35 alloys have Ti-rich columns surrounded by a Ti(1-x)Al(x)By tissue phase which is predominantly Al rich. Air-annealing TiB2.4 at temperatures above 500 degrees C leads to the formation of oxide scales that do not contain B and mostly consist of a rutile-TiO2 (s) phase. The resulting oxidation products are highly porous due to the evaporation of B2O3 (g) phase as well as the coarsening of TiO2 crystallites. This poor oxidation resistance is significantly improved by alloying with Al. While air-annealing at 800 degrees C for 0.5 h results in the formation of an similar to 1900-nm oxide scale on TiB2.4, the thickness of the scale formed on the Ti0.68Al0.32B1.35 alloys is similar to 470 nm. The enhanced oxidation resistance is attributed to the formation of a dense, protective Al-containing oxide scale that considerably decreases the oxygen diffusion rate by suppressing the oxide-crystallites coarsening. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

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  • 10.
    Bakhit, Babak
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Palisaitis, Justinas
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Wu, Zhengtao
    School of Electromechanical Engineering, Guangdong University of Technology, China.
    Sortica, Mauritio A.
    Applied Nuclear Physics, Department of Physics and Astronomy, Uppsala University, Sweden.
    Primetzhofer, Daniel
    Applied Nuclear Physics, Department of Physics and Astronomy, Uppsala University, Sweden.
    Persson, Per O. Å.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Rosén, Johanna
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Petrov, Ivan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. Materials Research Laboratory and Department of Materials Science, University of Illinois, USA; Department of Materials Science and Engineering, National Taiwan University of Science and Technology, Taiwan.
    Greene, Joseph E.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. Materials Research Laboratory and Department of Materials Science, University of Illinois, USA; Department of Materials Science and Engineering, National Taiwan University of Science and Technology, Taiwan.
    Greczynski, Grzegorz
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Age hardening in superhard ZrB2-rich Zr1-xTaxBy thin films2021Inngår i: Scripta Materialia, ISSN 1359-6462, E-ISSN 1872-8456, Vol. 191, s. 120-125Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We recently showed that sputter-deposited Zr1-xTaxBy thin films have hexagonal AlB2-type columnar nanostructure in which column boundaries are B-rich for x < 0.2, while Ta-rich for x ≥ 0.2. As-deposited layers with x ≥ 0.2 exhibit higher hardness and, simultaneously, enhanced toughness. Here, we study the mechanical properties of ZrB2.4, Zr0.8Ta0.2B1.8, and Zr0.7Ta0.3B1.5 films annealed in Ar atmosphere as a function of annealing temperature Ta up to 1200 °C. In-situ and ex-situ nanoindentation analyses reveal that all films undergo age hardening up to Ta = 800 °C, with the highest hardness achieved for Zr0.8Ta0.2B1.8 (45.5±1.0 GPa). The age hardening, which occurs without any phase separation or decomposition, can be explained by point-defect recovery that enhances chemical bond density. Although hardness decreases at Ta > 800 °C due mainly to recrystallization, column coarsening, and planar defect annihilation, all layers show hardness values above 34 GPa over the entire Ta range.

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  • 11.
    Bakhit, Babak
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Petrov, Ivan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. Univ Illinois, IL 61801 USA; Univ Illinois, IL 61801 USA.
    Greene, Joseph E
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. Univ Illinois, IL 61801 USA; Univ Illinois, IL 61801 USA.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Rosén, Johanna
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Greczynski, Grzegorz
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Controlling the B/Ti ratio of TiBx thin films grown by high-power impulse magnetron sputtering2018Inngår i: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 36, nr 3, artikkel-id 030604Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    TiBx thin films grown from compound TiB2 targets by magnetron sputter deposition are typically highly over-stoichiometric, with x ranging from 3.5 to 2.4, due to differences in Ti and B preferential-ejection angles and gas-phase scattering during transport from the target to the substrate. Here, the authors demonstrate that stoichiometric TiB2 films can be obtained using highpower impulse magnetron sputtering (HiPIMS) operated in power-controlled mode. The B/Ti ratio x of films sputter-deposited in Ar is controllably varied from 2.08 to 1.83 by adjusting the length of HiPIMS pulses t(on) between 100 and 30 mu s, while maintaining average power and pulse frequency constant. This results in peak current densities J(T), peak ranging from 0.27 to 0.88 A/cm(2). Energy- and time-resolved mass spectrometry analyses of the ion fluxes incident at the substrate position show that the density of metal ions increases with decreasing t(on) due to a dramatic increase in J(T, peak) resulting in the strong gas rarefaction. With t(on)amp;lt;60 mu s (J(T),(peak)amp;gt; 0.4 A/cm(2)), film growth is increasingly controlled by ions incident at the substrate, rather than neutrals, as a result of the higher plasma dencity and, hence, electron-impact ionization probablity. Thus, since sputter- ejected Ti atoms have a higher probability of being ionized than B atoms, due to their lower first-ionization potential and larger ionization cross-section, the Ti concentration in as-deposited films increases with decreasing ton (increasing J(T,peak)) as ionized sputtered species are steered to the substrate by the plasma in order to maintain charge neutrality. Published by the AVS.

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  • 12.
    Bakhit, Babak
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Primetzhofer, Daniel
    Uppsala University, Sweden.
    Pitthan, Eduardo
    Uppsala University, Sweden.
    Sortica, Mauricio A.
    Uppsala University, Sweden.
    Ntemou, Eleni
    Uppsala University, Sweden.
    Rosén, Johanna
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Petrov, Ivan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. University of Illinois, USA; National Taiwan University of Science and Technology, Taiwan.
    Greczynski, Grzegorz
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Systematic compositional analysis of sputter-deposited boron-containing thin films2021Inngår i: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 39, nr 6, artikkel-id 063408Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Boron-containing materials exhibit a unique combination of ceramic and metallic properties that are sensitively dependent on their given chemical bonding and elemental compositions. However, determining the composition, let alone bonding, with sufficient accuracy is cumbersome with respect to boron, being a light element that bonds in various coordinations. Here, we report on the comprehensive compositional analysis of transition-metal diboride (TMBx) thin films (TM = Ti, Zr, and Hf) by energy-dispersive x-ray spectroscopy (EDX), x-ray photoelectron spectroscopy (XPS), time-of-flight elastic recoil detection analysis (ToF-ERDA), Rutherford backscattering spectrometry (RBS), and nuclear reaction analysis (NRA). The films are grown on Si and C substrates by dc magnetron sputtering from stoichiometric TMB2 targets and have hexagonal AlB2-type columnar structures. EDX considerably overestimates B/TM ratios, x, compared to the other techniques, particularly for ZrBx. The B concentrations obtained by XPS strongly depend on the energy of Ar+ ions used for removing surface oxides and contaminants prior to analyses and are more reliable for 0.5 keV Ar+. ToF-ERDA, RBS, and NRA yield consistent compositions in TiBx. They also prove TiBx and ZrBx films to be homogeneous with comparable B/TM ratios for each film. However, ToF-ERDA, employing a 36-MeV 127I8+ beam, exhibits challenges in depth resolution and quantification of HfBx due to plural and multiple scattering and associated energy loss straggling effects. Compared to ToF-ERDA, RBS (for the film grown on C substrates) and NRA provide more reliable B/Hf ratios. Overall, a combination of methods is recommended for accurately pinpointing the compositions of borides that contain heavy transition metals.

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  • 13.
    Chang, Jui-Che
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Kostov Gueorguiev, Gueorgui
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Bakhit, Babak
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Greczynski, Grzegorz
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Eriksson, Fredrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Sandström, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Hsiao, Ching-Lien
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Domain epitaxial growth of Ta3N5 film on c-plane sapphire substrate2022Inngår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 443, artikkel-id 128581Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Tritantalum pentanitride (Ta3N5) semiconductor is a promising material for photoelectrolysis of water with high efficiency. Ta3N5 is a metastable phase in the complex system of TaN binary compounds. Growing stabilized single-crystal Ta3N5 films is correspondingly challenging. Here, we demonstrate the growth of a nearly single-crystal Ta3N5 film with epitaxial domains on c-plane sapphire substrate, Al2O3(0001), by magnetron sputter epitaxy. Introduction of a small amount ~2% of O2 into the reactive sputtering gas mixed with N2 and Ar facilitates the formation of a Ta3N5 phase in the film dominated by metallic TaN. In addition, we indicate that a single-phase polycrystalline Ta3N5 film can be obtained with the assistance of a Ta2O5 seed layer. With controlling thickness of the seed layer smaller than 10 nm and annealing at 1000 °C, a crystalline β phase Ta2O5 was formed, which promotes the domain epitaxial growth of Ta3N5 films on Al2O3(0001). The mechanism behind the stabilization of the orthorhombic Ta3N5 structure resides in its stacking with the ultrathin seed layer of orthorhombic β-Ta2O5, which is energetically beneficial and reduces the lattice mismatch with the substrate.

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  • 14.
    Chang, Jui-Che
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Eriksson, Fredrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Sortica, Mauricio A.
    Uppsala Univ, Sweden.
    Greczynski, Grzegorz
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Bakhit, Babak
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Hu, Zhang-Jun
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär ytfysik och nanovetenskap. Linköpings universitet, Tekniska fakulteten.
    Primetzhofer, Daniel
    Uppsala Univ, Sweden.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Hsiao, Ching-Lien
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Orthorhombic Ta3-xN5-yOy thin films grown by unbalanced magnetron sputtering: The role of oxygen on structure, composition, and optical properties2021Inngår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 406, artikkel-id 126665Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Direct growth of orthorhombic Ta3N5-type Ta-O-N compound thin films, specifically Ta3-xN5-yOy, on Si and sapphire substrates with various atomic fractions is realized by unbalanced magnetron sputtering. Low-degree fiber-textural Ta3-xN5-yOy films were grown through reactive sputtering of Ta in a gas mixture of N-2, Ar, and O-2 with keeping a partial pressure ratio of 3:2:0.1 in a total working pressure range of 5-30 mTorr. With increasing total pressure from 5 to 30 mTorr, the atomic fraction of O in the as-grown Ta3-xN5-yOy films was found to increase from 0.02 to 0.15 while that of N and Ta decrease from 0.66 to 0.54 and 0.33 to 0.31, respectively, leading to a decrease in b lattice constant up to around 1.3%. Metallic TaNx phases were formed without oxygen. For a working pressure of 40 mTorr, an amorphous, O-rich Ta-N-O compound film with a high O fraction of similar to 0.48, was formed, mixed with non-stoichiometric TaON and Ta2O5. By analyzing the plasma discharge, the increasing O incorporation is associated with oxide formation on top of the Ta target due to a higher reactivity of Ta with O than with N. The increase of O incorporation in the films also leads to a optical bandgap widening from similar to 2.22 to similar to 2.96 eV, which is in agreement with the compositional and structural changes from a crystalline Ta3-xN5-yOy to an amorphous O-rich Ta-O-N compound.

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  • 15.
    Deminskyi, Petro
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Kemi. Linköpings universitet, Tekniska fakulteten.
    Hsu, Chih-Wei
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Bakhit, Babak
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Rouf, Polla
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Kemi. Linköpings universitet, Tekniska fakulteten.
    Pedersen, Henrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Kemi. Linköpings universitet, Tekniska fakulteten.
    Surface ligand removal in atomic layer deposition of GaN using triethylgallium2021Inngår i: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 39, nr 1, artikkel-id 012411Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Gallium nitride (GaN) is one of the most important semiconductor materials in modern electronics. While GaN films are routinely deposited by chemical vapor deposition at around 1000 degrees C, low-temperature routes for GaN deposition need to be better understood. Herein, we present an atomic layer deposition (ALD) process for GaN-based on triethyl gallium (TEG) and ammonia plasma and show that the process can be improved by adding a reactive pulse, a "B-pulse" between the TEG and ammonia plasma, making it an ABC-type pulsed process. We show that the material quality of the deposited GaN is not affected by the B-pulse, but that the film growth per ALD cycle increases when a B-pulse is added. We suggest that this can be explained by the removal of ethyl ligands from the surface by the B-pulse, enabling a more efficient nitridation by the ammonia plasma. We show that the B-pulsing can be used to enable GaN deposition with a thermal ammonia pulse, albeit of x-ray amorphous films.

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  • 16.
    Dorri, Samira
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Eriksson, Fredrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Palisaitis, Justinas
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Persson, Per O A
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Bakhit, Babak
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Ghafoor, Naureen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Effects of stoichiometry and individual layer thickness ratio on the quality of epitaxial CrBx/TiBy superlattice thin films2023Inngår i: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 228, artikkel-id 111842Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Studies of single crystal artificial superlattices (SLs) of transition-metal (TM) diborides, which is instru- mental to understand hardening mechanisms at nanoscale, is lacking. Here, CrBx/TiBy (0001) diboride SLs [x,y E 1.7-3.3] are grown epitaxially on Al2O3(0001) substrates by direct-current magnetron sputter epitaxy. Growth conditions for obtaining well-defined SLs with good interface quality are found at 4 mTorr Ar pressure and 600 degrees C. 1 -mu m-thick SL films deposited with modulation periods A between 1 and 10 nm, and A=6 nm SLs with TiBy-to-A layer thickness ratios F ranging from 0.2 to 0.8 are studied. SLs with A=6 nm and F in the range of 0.2-0.4, with a near stoichiometric B/TM ratio, exhibit the high- est structural quality. The effects of F and stoichiometries (B/TM ratio) on the distribution of B in the SL structures are discussed. By increasing the relative thickness of TiBy, the crystalline quality of SLs starts to deteriorate due to B segregation in over-stoichiometric TiBy, resulting in narrow epitaxial SL columnar growth with structurally-distorted B-rich boundaries. Moreover, increasing the relative thickness of under-stoichiometric CrBx enhances the SL quality and hinders formation of B-rich boundaries. The SLs are found to exhibit hardness values in the range of 29-34 GPa.(c) 2023 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

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  • 17.
    Dorri, Samira
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Palisaitis, Justinas
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Greczynski, Grzegorz
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Petrov, Ivan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. University of Illinois at Urbana-Champaign, USA; National Taiwan University of Science and Technology, Taiwan.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Bakhit, Babak
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Oxidation kinetics of overstoichiometric TiB2 thin films grown by DC magnetron sputtering2022Inngår i: Corrosion Science, ISSN 0010-938X, E-ISSN 1879-0496, Vol. 206, artikkel-id 110493Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We systematically study the oxidation properties of sputter-deposited TiB2.5 coatings up to 700 °C. Oxide-scale thickness dox increases linearly with time ta for 300, 400, 500, and 700 °C, while an oxidation-protective behavior occurs with dox=250∙ta0.2 at 600 °C. Oxide-layer’s structure changes from amorphous to rutile/anatase-TiO2 at temperatures ≥ 500 °C. Abnormally low oxidation rate at 600 °C is attributed to a highly dense columnar TiO2-sublayer growing near oxide/film interface with a top-amorphous thin layer, suppressing oxygen diffusion. A model is proposed to explain the oxide-scale evolution at 600 °C. Decreasing heating rate to 1.0 °C/min plays a noticeable role in the TiB2.5 oxidation.

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  • 18.
    Gaggio, Benedetta
    et al.
    Univ Cambridge, England.
    Jan, Atif
    Univ Cambridge, England.
    Muller, Moritz
    Univ Cambridge, England.
    Salonikidou, Barbara
    Univ Cambridge, England.
    Bakhit, Babak
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. Univ Cambridge, England.
    Hellenbrand, Markus
    Univ Cambridge, England.
    Di Martino, Giuliana
    Univ Cambridge, England.
    Yildiz, Bilge
    MIT, MA 02139 USA.
    MacManus-Driscoll, Judith L.
    Univ Cambridge, England.
    Sodium-Controlled Interfacial Resistive Switching in Thin Film Niobium Oxide for Neuromorphic Applications2024Inngår i: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A double layer 2-terminal device is employed to show Na-controlled interfacial resistive switching and neuromorphic behavior. The bilayer is based on interfacing biocompatible NaNbO3 and Nb2O5, which allows the reversible uptake of Na+ in the Nb2O5 layer. We demonstrate voltage-controlled interfacial barrier tuning via Na+ transfer, enabling conductivity modulation and spike-amplitude- and spike-timing-dependent plasticity. The neuromorphic behavior controlled by Na+ ion dynamics in biocompatible materials shows potential for future low-power sensing electronics and smart wearables with local processing.

  • 19.
    Ghafoor, Naureen
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Dorri, Samira
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Palisaitis, Justinas
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Rogström, Lina
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Bakhit, Babak
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Greczynski, Grzegorz
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Phase separation paths in metastable Zr1-xAlxN monolithic layers compared to multilayers with TiN: Growth versus annealing temperatures2023Inngår i: Materialia, E-ISSN 2589-1529, Vol. 28, artikkel-id 101758Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Metastable super-saturated Zr1_xAlxN alloys tend to phase separate into the equilibrium cubic (c) ZrN and wurtzite (w) AlN due to a deep miscibility gap. Transformation is shown here to follow distinctly different paths depending on if Zr1_xAlxN (x = 0.3 and 0.6) is sputter deposited as a single layer or multi-layered with TiN, and further varied by post-deposition annealing. Using in situ high-energy synchrotron wide-angle X-ray scattering and analytical transmission electron microscopy, surface segregation effects are compared to secondary phase transformations occurring in as-deposited layers during thermal annealing up to 1000 degrees C. For the primary phase transformation from the vapor phase, w-AlN nucleates and an AlN-ZrN labyrinthine structure evolves at elevated deposition temperature with semi-coherent interfaces over several nanometers, where the higher Al content narrows the structure in both single and multilayers. Transformation in thinner alloy layers is governed by epitaxial forces which stabilize single-phase c-Zr0.4Al0.6N, which enables c-Zr0.4Al0.6N/TiN superlattice growth at temperatures as low as 350 degrees C. Regardless of the decomposition route, the formation of c-AlN is impeded and w-AlN instantaneously forms during transformation. In contrast, isostructural decomposition into w-AlN and w-Zr (Al)N occurs in w-Zr0.4Al0.6N alloys during annealing.

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  • 20.
    Greczynski, Grzegorz
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Bakhit, Babak
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    High Si content TiSiN films with superior oxidation resistance2020Inngår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 398, artikkel-id 126087Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The high-temperature oxidation resistance of Ti1-xSixN films with Si content varying in wide range, 0.13 &lt;= x &lt;= 0.91, is evaluated. Films are grown in Ar/N-2 atmospheres using a hybrid high-power impulse and dc magnetron sputtering (HiPIMS/DCMS) configuration with Si target powered by HiPIMS and Ti target operated in DCMS mode. The substrate bias is synchronized to the Si+-rich portions of the HiPIMS pulses in order to promote solid solution formation. A combination of X-ray photoelectron spectroscopy, elastic recoil detection analysis, and cross-sectional scanning electron microscopy reveals a sharp increase in the oxidation resistance for layers with x &gt; 0.50. The thickness of the oxide layer, following 1 h anneal at 800 degrees C in air, is in the range 150-200 nm for 0.13 &lt;= x &lt;= 0.50 and decreases to only 4 nm with x = 0.91, which is similar to 30 times lower than for the best performing Ti1-xAlxN film (x = 0.64) tested under the same conditions. The oxide forming on top of Ti1-xSixN films with x = 0.41 consists of a SiO2-TiO2 two-phase mixture with a molar ratio given by Si/Ti ratio. In Ti1-xSixN layers with x &lt;= 0.31, the presence of grain boundaries, which act as diffusion paths facilitates Si diffusion towards the bulk of the film resulting in that TiO2, the thermodynamically more stable oxide, terminates the surface. Ti0.09Si0.91N films, are essentially unaffected by the anneal and exhibit a hardness of 23 GPa, which is similar to 30% higher than for the reference SiNz film. Moreover, we demonstrate that 25 nm thick Ti0.09Si0.91N capping layers successfully prevent Ti(0.36A)l(0.64)N oxidation at 800 degrees C. Such approach provides superior oxidation protection compared to alloying TiAlN with Si. Our results suggest that multilayers including nm thin layers of high Si-content TiSiN is a most effective approach to improve high-temperature oxidation resistance of functional ceramic thin films.

  • 21.
    Hellenbrand, Markus
    et al.
    Univ Cambridge, England.
    Bakhit, Babak
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. Univ Cambridge, England; Univ Cambridge, England.
    Dou, Hongyi
    Purdue Univ, IN 47907 USA.
    Xiao, Ming
    Univ Cambridge, England.
    Hill, Megan O.
    Univ Cambridge, England.
    Sun, Zhuotong
    Univ Cambridge, England.
    Mehonic, Adnan
    UCL, England.
    Chen, Aiping
    Los Alamos Natl Lab, NM 87545 USA.
    Jia, Quanxi
    Univ Buffalo, NY 14260 USA.
    Wang, Haiyan
    Purdue Univ, IN 47907 USA.
    MacManus-Driscoll, Judith L.
    Univ Cambridge, England.
    Thin-film design of amorphous hafnium oxide nanocomposites enabling strong interfacial resistive switching uniformity2023Inngår i: Science Advances, E-ISSN 2375-2548, Vol. 9, nr 25, artikkel-id eadg1946Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A design concept of phase-separated amorphous nanocomposite thin films is presented that realizes interfacial resistive switching (RS) in hafnium oxide-based devices. The films are formed by incorporating an average of 7% Ba into hafnium oxide during pulsed laser deposition at temperatures &lt;= 400 degrees C. The added Ba prevents the films from crystallizing and leads to similar to 20-nm-thin films consisting of an amorphous HfOx host matrix interspersed with similar to 2-nm-wide, similar to 5-to-10-nm-pitch Ba-rich amorphous nanocolumns penetrating approximately two-thirds through the films. This restricts the RS to an interfacial Schottky-like energy barrier whose magnitude is tuned by ionic migration under an applied electric field. Resulting devices achieve stable cycle-to-cycle, device-to-device, and sample-to-sample reproducibility with a measured switching endurance of &gt;= 10(4) cycles for a memory window &gt;= 10 at switching voltages of +/- 2 V. Each device can be set to multiple intermediate resistance states, which enables synaptic spike-timing-dependent plasticity. The presented concept unlocks additional design variables for RS devices.

    Fulltekst (pdf)
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  • 22.
    Hsu, Chih-Wei
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Martinovic, Ivan
    Linköpings universitet, Tekniska fakulteten. Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial.
    Magnusson, Roger
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Bakhit, Babak
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Palisaitis, Justinas
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Persson, Per O A
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Rouf, Polla
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Kemi. Linköpings universitet, Tekniska fakulteten.
    Pedersen, Henrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Kemi. Linköpings universitet, Tekniska fakulteten.
    Homogeneous high In content InxGa1-x N films by supercycle atomic layer deposition2022Inngår i: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 40, nr 6, artikkel-id 060402Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    InxGa1-x N is a strategically important material for electronic devices given its tunable bandgap, modulated by the In/Ga ratio. However, current applications are hindered by defects caused by strain relaxation and phase separation in the material. Here, we demonstrate growth of homogeneous InxGa1-x N films with 0.3 &lt; x &lt; 0.8 up to similar to 30 nm using atomic layer deposition (ALD) with a supercycle approach, switching between InN and GaN deposition. The composition is uniform along and across the films, without signs of In segregation. The InxGa1-x N films show higher In-content than the value predicted by the supercycle model. A more pronounced reduction of GPC(InN) than GPC(GaN) during the growth processes of InN and GaN bilayers is concluded based on our analysis. The intermixing between InN and GaN bilayers is suggested to explain the enhanced overall In-content. Our results show the advantage of ALD to prepare high-quality InxGa1-x N films, particularly with high In-content, which is difficult to achieve with other growth methods.

    Fulltekst (pdf)
    fulltext
  • 23.
    Hsu, Tun-Wei
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Greczynski, Grzegorz
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Boyd, Robert
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Plasma och ytbeläggningsfysik. Linköpings universitet, Tekniska fakulteten.
    Kolozsvári, Szilárd
    PLANSEE Composite Materials GmbH, Germany.
    Polcik, Peter
    PLANSEE Composite Materials GmbH, Germany.
    Bolz, Stephan
    CemeCon AG, Germany.
    Bakhit, Babak
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Influence of Si content on phase stability and mechanical properties of TiAlSiN films grown by AlSi-HiPIMS/Ti-DCMS co-sputtering2021Inngår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 427, artikkel-id 127661Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ti1-x(AlySi1-y)xN coatings covering a wide compositional range, 0.38 < x < 0.76 and 0.68 ≤ y ≤ 1.00, are deposited to investigate the influence of Al+/Si+ ion irradiation on microstructural and mechanical properties. The samples are grown in Ar/N2 atmosphere by the hybrid high-power impulse and dc magnetron co-sputtering (HiPIMS/DCMS) method with substrate bias synchronized to the Al+/Si+-rich portion of the HiPIMS pulses. Two Ti targets are operated in DCMS mode, while one AlSi target is operated in HiPIMS mode. Four different AlSi target compositions are used: Al1.0Si0.0, Al0.9Si0.1, Al0.8Si0.2, and Al0.6Si0.4. X-ray diffractometry reveals that films without Si (i.e., y = 1.0) have high Al solubility in NaCl-structure, c-TiAlN, up to x ≤ 0.67 no w-AlN is detected. Once Si (y < 1.0) is introduced the Al solubility limit decreases, but remains higher than other PVD techniques, along with grain refinement and the formation of a SiNz rich tissues phase, as shown by transmission electron microscopy. The nanoindentation hardness is high (~ 30 GPa) for all films that do not contain the w-AlN phase. All the coatings have compressive stresses lower than -3 GPa. Interestingly, a range of films with different compositions displayed both high hardness (~ 30 GPa) and low residual stress (σ < 0.5 GPa). Such an unique combination of properties highlights the benefits of using HiPIMS/DCMS configuration with metal-ion-synchronized substrate bias, which utilizes the Al+/Si+ supplantation effect and minimizes the Ar+ incorporation.

    Fulltekst (pdf)
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  • 24.
    Ji, Fuxiang
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Elektroniska och fotoniska material. Linköpings universitet, Tekniska fakulteten.
    Klarbring, Johan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Zhang, Bin
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Elektroniska och fotoniska material. Linköpings universitet, Tekniska fakulteten.
    Wang, Feng
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Elektroniska och fotoniska material. Linköpings universitet, Tekniska fakulteten.
    Wang, Linqin
    School of Science Westlake University Hangzhou, P.R. China.
    Miao, Xiaohe
    Westlake University Hangzhou, P.R. China.
    Ning, Weihua
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Elektroniska och fotoniska material. Linköpings universitet, Tekniska fakulteten. Soochow University Suzhou, P. R. China.
    Zhang, Muyi
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Elektroniska och fotoniska material. Linköpings universitet, Tekniska fakulteten.
    Cai, Xinyi
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Elektroniska och fotoniska material. Linköpings universitet, Tekniska fakulteten.
    Bakhit, Babak
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Magnuson, Martin
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Ren, Xiaoming
    State Key Laboratory of Materials‐Oriented Chemical Engineering and College of Chemistry and Molecular Engineering Nanjing Tech University Nanjing, P.R. China.
    Sun, Licheng
    Center of Artificial Photosynthesis for Solar Fuels, School of Science Westlake University Hangzhou,P.R. China.
    Fahlman, Mats
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Laboratoriet för organisk elektronik. Linköpings universitet, Tekniska fakulteten.
    Buyanova, Irina A
    Linköpings universitet, Tekniska fakulteten. Linköpings universitet, Institutionen för fysik, kemi och biologi, Elektroniska och fotoniska material.
    Chen, Weimin
    Linköpings universitet, Tekniska fakulteten. Linköpings universitet, Institutionen för fysik, kemi och biologi, Elektroniska och fotoniska material.
    Simak, Sergei I
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten. Uppsala University Uppsala SE‐75120 Sweden.
    Abrikosov, Igor A.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Gao, Feng
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Elektroniska och fotoniska material. Linköpings universitet, Tekniska fakulteten.
    Remarkable Thermochromism in the Double Perovskite Cs2NaFeCl62023Inngår i: Advanced Optical Materials, ISSN 2162-7568, E-ISSN 2195-1071, artikkel-id 2301102Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Lead-free halide double perovskites (HDPs) have emerged as a new generation of thermochromic materials. However, further materials development and mechanistic understanding are required. Here, a highly stable HDP Cs2NaFeCl6 single crystal is synthesized, and its remarkable and fully reversible thermochromism with a wide color variation from light-yellow to black over a temperature range of 10 to 423 K is investigated. First-principles, density functional theory (DFT)-based calculations indicate that the thermochromism in Cs2NaFeCl6 is an effect of electron–phonon coupling. The temperature sensitivity of the bandgap in Cs2NaFeCl6 is up to 2.52 meVK−1 based on the Varshni equation, which is significantly higher than that of lead halide perovskites and many conventional group-IV, III–V semiconductors. Meanwhile, this material shows excellent environmental, thermal, and thermochromic cycle stability. This work provides valuable insights into HDPs' thermochromism and sheds new light on developing efficient thermochromic materials.

    Fulltekst (pdf)
    fulltext
  • 25.
    Le Febvrier, Arnaud
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Gambino, Davide
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Giovannelli, Fabien
    Univ Tours, France.
    Bakhit, Babak
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Hurand, Simon
    Univ Poitiers, France.
    Abadias, Gregory
    Univ Poitiers, France.
    Alling, Björn
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Eklund, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    p-type behavior of CrN thin films via control of point defects2022Inngår i: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 105, nr 10, artikkel-id 104108Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We report the results of a combined experimental and theoretical study on nonstoichiometric CrN1+δ thinfilms grown by reactive magnetron sputtering on c-plane sapphire and MgO (100) substrates in an Ar/N2 gasmixture using different percentages of N2. There is a transition from n-type to p-type behavior in the layersas a function of nitrogen concentration varying from 48 to 52 at. % in CrN films. The compositional changefollows a similar trend for all substrates, with a N/Cr ratio increasing from approximately 0.7 to 1.06–1.11 byincreasing the percentage of N2 in the gas flow ratio. As a result of the change in stoichiometry, the latticeparameter and the Seebeck coefficient increase together with the increase of N in CrN1+δ ; in particular, theSeebeck value coefficient transitions from –50 μV K–1 for CrN0.97 to +75μV K–1 for CrN1.1. Density functionaltheory calculations show that Cr vacancies can account for the change in the Seebeck coefficient, since they pushthe Fermi level down in the valence band, whereas N interstitial defects in the form of N2 dumbbells are neededto explain the increasing lattice parameter. Calculations including both types of defects, which have a strongtendency to bind together, reveal a slight increase in the lattice parameter and a simultaneous formation of holesin the valence band. To explain the experimental trends, we argue that both Cr vacancies and N2 dumbbells,possibly in combined configurations, are present in the films. We demonstrate the possibility of controlling thesemiconducting behavior of CrN with intrinsic defects from n to p type, opening possibilities to integrate thiscompound in energy-harvesting thermoelectric devices.

    Fulltekst (pdf)
    fulltext
  • 26.
    Li, Xiao
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Bakhit, Babak
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Joesaar, M. P. Johansson
    SECO Tools AB, Sweden.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Petrov, Ivan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. Univ Illinois, USA; Natl Taiwan Univ Sci & Technol, Taiwan.
    Greczynski, Grzegorz
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Toward energy-efficient physical vapor deposition: Routes for replacing substrate heating during magnetron sputter deposition by employing metal ion irradiation2021Inngår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 415, artikkel-id 127120Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In view of the increasing demand for achieving sustainable development, the quest for lowering energy consumption during thin film growth by magnetron sputtering becomes of particular importance. In addition, there is a demand for low-temperature growth of dense, hard coatings for protecting temperature-sensitive substrates. Here, we explore a method, in which thermally-driven adatom mobility, necessary to obtain high-quality fully-dense films, is replaced with that supplied by effective low-energy recoil creation resulting from high-mass metal ion irradiation of the growing film surface. This approach allows the growth of dense and hard films with no external heating at substrate temperatures T-s not exceeding 130 degrees C in a hybrid high-power impulse and de magnetron co-sputtering (HiPIMS/DCMS) setup involving a high mass (m &gt; 180 amu) HiPIMS target and metal- ion-synchronized bias pulses. We specifically investigate the effect of the metal ion mass on the extent of densification, phase content, nanostructure, and mechanical properties of metastable cubic Ti0.50Al0.50N based thin films, which present outstanding challenges for phase stability control. Ti0.50Al0.50N based thin films are irradiated by group VIB transition metal (TM) target ions generated by Me-HiPIMS discharge, in which Me = Cr (m(Cr)= 52.0 amu), Mo (m(Mo) = 96.0 amu), and W (m(W) = 183.8 amu). Three series of (Ti1-yAly)(1-x)MexN films are grown with x = Me/(Me+Al+Ti) varied intentionally by adjusting the DCMS powers, while y = Al/(Al+Ti) also varies as a result of Me+ ion irradiation. Results reveal a strong dependence of film properties on the mass of the HiPIMS-generated metal ions. All layers deposited with Cr+ irradiation exhibit porous nanostructure, high ox- ygen content, and poor mechanical properties. In contrast, (Ti1-yAly)(1-x)WxN films are fully-dense even with the lowest W concentration, x = 0.09, show no evidence of hexagonal AlN precipitation, and exhibit state-of the-art mechanical properties typical of Ti0.50Al0.50N grown at 500 degrees C. The process energy consumption is lowered by 64% with no negative impact on the coating quality. TRIM simulations provide an insight into the densification mechanisms.

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  • 27.
    Li, Xiao
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Bakhit, Babak
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Joesaar, M. P. Johansson
    SECO Tools AB, Sweden.
    Petrov, Ivan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. Univ Illinois, IL 61801 USA; Natl Taiwan Univ Sci & Technol, Taiwan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Greczynski, Grzegorz
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Dense, single-phase, hard, and stress-free Ti0.32Al0.63W0.05N films grown by magnetron sputtering with dramatically reduced energy consumption2022Inngår i: Scientific Reports, E-ISSN 2045-2322, Vol. 12, nr 1, artikkel-id 2166Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The quest for lowering energy consumption during thin film growth, as by magnetron sputtering, becomes of particular importance in view of sustainable development goals. A recently proposed solution combining high power impulse and direct current magnetron sputtering (HiPIMS/DCMS) relies on the use of heavy metal-ion irradiation, instead of conventionally employed resistive heating, to provide sufficient adatom mobility, in order to obtain high-quality dense films. The major fraction of process energy is used at the sputtering sources rather than for heating the entire vacuum vessel. The present study aims to investigate the W+ densification effects as a function of increasing Al content in (Ti1-yAly)(1-x)WxN films covering the entire range up to the practical solubility limits (y similar to 0.67). Layers with high Al content are attractive to industrial applications as the high temperature oxidation resistance increases with increasing Al concentration. The challenge is, however, to avoid precipitation of the hexagonal wurtzite AIN phase, which is softer. We report here that (T1-yAly)(1-x)WxN layers with y= 0.66 and x= 0.05 grown by a combination ofW-HiPIMS and TiAI-DCMS with the substrate bias V-s synchronized to the W+-rich fluxes (to provide mobility in the absence of substrate heating) possess single-phase NaCl-structure, as confirmed by XRD and SAED patterns. The evidence provided by XTEM images and the residual oxygen content obtained from ERDA analyses reveals that the alloy films are dense without discernable porosity. The nanoindentation hardness is comparable to that of TiAlN films grown at 400-500 degrees C, while the residual stresses are very low. We established that the adatom mobility due to the heavy ion W+ irradiation (in place of resistive heating) enables the growth of high-quality coatings at substrate temperatures not exceeding 130 degrees C provided that the W+ momentum transfer per deposited metal atom is sufficiently high. The benefit of this novel film growth approach is not only the reduction of the process energy consumption by 83%, but also the possibility to coat temperature-sensitive substrates.

    Fulltekst (pdf)
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  • 28.
    Li, Xiao
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Bakhit, Babak
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Joesaar, M. P. Johansson
    SECO Tools AB, Sweden.
    Petrov, Ivan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. Univ Illinois, IL 61801 USA; Univ Illinois, IL 61801 USA; Natl Taiwan Univ Sci & Technol, Taiwan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Greczynski, Grzegorz
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Towards energy-efficient physical vapor deposition: Mapping out the effects of W+ energy and concentration on the densification of TiAlWN thin films grown with no external heating2021Inngår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 424, artikkel-id 127639Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Hybrid high power impulse/direct current magnetron sputtering (HiPIMS/DCMS) film growth technique with metal-ion-synchronized substrate bias allows for significant energy savings as compared to conventional PVD methods. For carefully selected type of metal ion irradiation, taking into account ion mass, ionization potential, and reactivity towards working gas, fully dense and hard films can be obtained with no intentional substrate heating. The thermally-driven adatom mobility, which is an essential densification mechanism in conventional film growth that takes place at elevated temperatures, is replaced with that supplied by effective low-energy recoil creation. In this contribution we explore effects of the high-mass W+ irradiation, which has proven to be the most efficient in densifying Ti0.50Al0.50N layers, serving here as a model system, grown with no substrate heating. We study the effects of two essential parameters: W+ energy EW+ and W concentration x, on film porosity, phase content, nanostructure, and mechanical properties. EW+ varies from similar to 90 to similar to 630 eV (controlled by substrate bias voltage amplitude V-s) and x from 0.02 to 0.12 (controlled by the HiPIMS pulse length), while the HiPIMS peak target current is kept constant. Results reveal that a strong coupling exists between the W+ incident energy and the minimum W concentration required to grow dense layers.

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  • 29.
    Nzulu, Gabriel K.
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. Gold Corporation, Ghana.
    Bakhit, Babak
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Högberg, Hans
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Magnuson, Martin
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Elucidating Pathfinding Elements from the Kubi Gold Mine in Ghana2021Inngår i: Minerals, E-ISSN 2075-163X, Vol. 11, nr 9, artikkel-id 912Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    X-ray photoelectron spectroscopy (XPS) and energy-dispersive X-ray spectroscopy (EDX) are applied to investigate the properties of fine-grained concentrates on artisanal, small-scale gold mining samples from the Kubi Gold Project of the Asante Gold Corporation near Dunwka-on-Offinin the Central Region of Ghana. Both techniques show that the Au-containing residual sediments are dominated by the host elements Fe, Ag, Al, N, O, Si, Hg, and Ti that either form alloys with gold or with inherent elements in the sediments. For comparison, a bulk nugget sample mainly consisting of Au forms an electrum, i.e., a solid solution with Ag. Untreated (impure) sediments, fine-grained Au concentrate, coarse-grained Au concentrate, and processed ore (Au bulk/nugget)samples were found to contain clusters of O, C, N, and Ag, with Au concentrations significantly lower than that of the related elements. This finding can be attributed to primary geochemical dispersion, which evolved from the crystallization of magma and hydrothermal liquids as well as the migration of metasomatic elements and the rapid rate of chemical weathering of lateralization in secondary processes. The results indicate that Si and Ag are strongly concomitant with Au because of their eutectic characteristics, while N, C, and O follow alongside because of their affinity to Si. These non-noble elements thus act as pathfinders for Au ores in the exploration area. This paper further discusses relationships between gold and sediments of auriferous lodes as key to determining indicator minerals of gold in mining sites.

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  • 30.
    Paschalidou, Eirini-Maria
    et al.
    Uppsala Univ, Sweden.
    Shu, Rui
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Boyd, Robert
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Papaderakis, Athanasios A.
    Univ Manchester, England; Univ Manchester, England.
    Bakhit, Babak
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Le Febvrier, Arnaud
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Greczynski, Grzegorz
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Eklund, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Nyholm, Leif
    Uppsala Univ, Sweden.
    The effect of the Nb concentration on the corrosion resistance of nitrogen-containing multicomponent TiZrTaNb-based films in acidic environments2022Inngår i: Journal of Alloys and Compounds, ISSN 0925-8388, E-ISSN 1873-4669, Vol. 927, artikkel-id 167005Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Multicomponent as well as high-entropy-based nitrides have received increasing interest in the field of materials science and engineering. The structural characteristics of these compounds result in a mix of covalent, metallic, and ionic bonds that give rise to a number of attractive properties including high hardness, electrical and thermal conductivities as well as chemical stability. These properties render these materials promising candidates for various industrial applications involving harsh operating conditions. Herein, the corrosion resistances of dc magnetron sputtered nitrogen-containing TiZrTaNby thin films with Nb content ranging from 8.0 to 24.5 at% have been investigated to provide insights regarding the corrosion resistances of multicomponent systems containing more than one passive element. The corrosion resistances and anodic behavior of the films were examined by electrochemical means in 0.1 M H2SO4 and 0.1 M HCl solutions. The results demonstrate that despite the significant differences in the concentration of one of the two main passive elements in the films i.e., Nb, the corrosion resistance did not differ significantly between the films. To provide insights into this phenomenon, the surface chemical state and composition of the prepared films were probed using X-ray photoelectron spectroscopy. It was shown that all samples exhibited Ta-rich surfaces after positive polarization up to 3.0 V vs. Ag/AgCl (3 M NaCl) as a result of the anodic dissolution of Zr and Ti. The thickness of the oxide layer formed upon different anodic polarization was studied using transmission electron microscopy, while complementary electrochemical impedance studies were performed. The extent of Nb dissolution from the surface of the films was, on the other hand, found to be small. These findings highlight the dominant role of Ta in the passivation of the films and demonstrate the minor effect of Nb concentration on the corrosion resistances of the films. However, it was demonstrated that the presence of Nb was still important for the corrosion resistance of the films above 1.4 V vs. Ag/AgCl (3 M NaCl), when replacing Nb with Cr, due to transpassive dissolution of Cr. These results facilitate the design of highly corrosion resistant multicomponent nitrides containing more than one passive element.(c) 2022 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

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  • 31.
    Pshyk, A. V.
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. Adam Mickiewicz Univ, Poland; Empa Swiss Fed Labs Mat Testing & Res, Switzerland.
    Vasylenko, A.
    Univ Liverpool, England.
    Bakhit, Babak
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Schweizer, P.
    Empa Swiss Fed Labs Mat Testing & Res, Switzerland.
    Edwards, T. E. J.
    Empa Swiss Fed Labs Mat Testing & Res, Switzerland.
    Michler, J.
    Empa Swiss Fed Labs Mat Testing & Res, Switzerland.
    Greczynski, Grzegorz
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    High-entropy transition metal nitride thin films alloyed with Al: Microstructure, phase composition and mechanical properties2022Inngår i: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 219, artikkel-id 110798Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Deviation from equimolar composition in high-entropy multielement ceramics offers a possibility of fine-tuning the materials properties for targeted application. Here, we present a systematic experimental and theoretical study on the effects of alloying equimolar pentanary (TiHfNbVZr)N and hexanary (TiHfNbVZrTa)N high-entropy nitrides with Al. Although being predicted to be metastable by ab initio density-functional theory calculations, single-phase fcc NaCl-structured solid solution thin films with Al solubility limits as high as x similar to 0.51-0.61 in (TiHfNbVZr)(1-x)AlxN and x similar to 0.45-0.64 in (TiHfNbVZrTa)(1-x)AlxN are synthesised utilizing a hybrid deposition technique that offers dynamic mixing of film atoms from Al+ subplantation and non-equilibrium growth conditions leading to quenching of the desired film structure. In experimental studies supplemented with density-functional theory calculations, it is demonstrated that Al concentration in alloys with the multielement compositions of high-entropy nitride thin films determine hardness, yield strength, toughness, and ability to deform plastically up to fracture due to different deformation mechanisms arising from the electronic structure and phase compositions. (C) 2022 The Author(s). Published by Elsevier Ltd.

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  • 32.
    Pshyk, Oleksandr
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Petrov, Ivan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. Univ Illinois, IL 61801 USA; Natl Taiwan Univ Sci & Technol, Taiwan.
    Bakhit, Babak
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Lu, Jun
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Greczynski, Grzegorz
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Energy-efficient physical vapor deposition of dense and hard Ti-Al-W-N coatings deposited under industrial conditions2023Inngår i: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 227, artikkel-id 111753Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Decreasing the growth temperature to lower energy consumption and enable deposition on temperature-sensitive substrates during thin film growth by magnetron sputtering is crucial for sustainable develop-ment. High-mass metal ion irradiation of the growing film surface with ion energy controlled by metal-ion-synchronized biasing, allows to replace conventionally-used resistive heating, as was recently demonstrated in experiments involving a hybrid high-power impulse and dc magnetron co-sputtering (HiPIMS/DCMS) setup and stationary substrates. Here, we report the extension of the method to indus-trial scale conditions. As a model-case towards understanding the role of one-fold substrate rotation on Ti0.50Al0.50N film growth employing W irradiation, we investigate the effect of two parameters: W ion energy (controlled in the range 45 &lt;= EW &lt;= 630 eV by the amplitude of synchronized substrate bias voltage) and W ion dose per deposited metal atom (determined by the target power). We show that the efficient densification of coatings grown without external heating can be achieved by minimizing the thickness of DCMS-deposited Ti0.50Al0.50N layer that is exposed to an W ion flux, or by increasing EW, at a given Ti0.50Al0.50N thickness.(c) 2023 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

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  • 33.
    Rouf, Polla
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Kemi. Linköpings universitet, Tekniska fakulteten.
    O´brien, Nathan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Kemi. Linköpings universitet, Tekniska fakulteten.
    Buttera, Sydney C.
    Department of Chemistry, Carleton University, Ottawa, Ontario, Canada.
    Martinovic, Ivan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Bakhit, Babak
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Martinsson, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biofysik och bioteknik. Linköpings universitet, Tekniska fakulteten.
    Palisaitis, Justinas
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Hsu, Chih-Wei
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Pedersen, Henrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Kemi. Linköpings universitet, Tekniska fakulteten.
    Epitaxial GaN using Ga(NMe2)3 and NH3 plasma by Atomic Layer Deposition2020Inngår i: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 8, nr 25, s. 8457-8465Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Low temperature deposition of high-quality epitaxial GaN is crucial for its integration in electronic applications. Chemical vapor deposition at approximately 800 °C using SiC with an AlN buffer layer or nitridized sapphire as substrate is used to facilitate the GaN growth. Here, we present a low temperature atomic layer deposition (ALD) process using tris(dimethylamido)gallium(III) with NH3 plasma. The ALD process shows self-limiting behaviour between 130–250 °C with a growth rate of 1.4 Å per cycle. The GaN films produced were crystalline on Si (100) at all deposition temperatures with a near stochiometric Ga/N ratio with low carbon and oxygen impurities. When GaN was deposited on 4H-SiC, the films grew epitaxially without the need for an AlN buffer layer, which has never been reported before. The bandgap of the GaN films was measured to be ∼3.42 eV and the Fermi level showed that the GaN was unintentionally n-type doped. This study shows the potential of ALD for GaN-based electronic devices.

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  • 34.
    Rouf, Polla
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Kemi. Linköpings universitet, Tekniska fakulteten.
    Palisaitis, Justinas
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Bakhit, Babak
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    O´brien, Nathan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Kemi. Linköpings universitet, Tekniska fakulteten.
    Pedersen, Henrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Kemi. Linköpings universitet, Tekniska fakulteten.
    In0.5Ga0.5N layers by atomic layer deposition2021Inngår i: Journal of Materials Chemistry C, ISSN 2050-7526, E-ISSN 2050-7534, Vol. 9, nr 38, s. 13077-13080Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present an ALD approach to metastable In1-xGaxN with 0.1 &lt; x &lt; 0.5 based on solid In- and Ga-precursors that were co-sublimed into the deposition chamber in one pulse. A near In0.5Ga0.5N film with a bandgap value of 1.94 eV was achieved on a Si(100) substrate. Epitaxial In1-xGaxN(0002) was successfully grown directly on the 4H-SiC(0001) substrate.

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  • 35.
    Rouf, Polla
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Kemi. Linköpings universitet, Tekniska fakulteten.
    Samii, Rouzbeh
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Kemi. Linköpings universitet, Tekniska fakulteten.
    Rönnby, Karl
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Kemi. Linköpings universitet, Tekniska fakulteten.
    Bakhit, Babak
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Buttera, Sydney C.
    Carleton Univ, Canada.
    Martinovic, Ivan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Ojamäe, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Kemi. Linköpings universitet, Tekniska fakulteten.
    Chih-Wei, Chih-Wei
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Palisaitis, Justinas
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Kessler, Vadim
    Swedish Univ Agr Sci, Sweden.
    Pedersen, Henrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Kemi. Linköpings universitet, Tekniska fakulteten.
    O´brien, Nathan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Kemi. Linköpings universitet, Tekniska fakulteten.
    Hexacoordinated Gallium(III) Triazenide Precursor for Epitaxial Gallium Nitride by Atomic Layer Deposition2021Inngår i: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 33, nr 9, s. 3266-3275Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Gallium nitride (GaN) is the main component of modern-day high electron mobility transistors due to its favorable electronic properties. As electronic devices become smaller with more complex surface architecture, the ability to deposit high-quality GaN films at low temperatures is required. Herein, we report a new highly volatile Ga(III) triazenide precursor and demonstrate its ability to deposit high-quality epitaxial GaN by atomic layer deposition (ALD). This new Ga(III) triazenide, the first hexacoordinated Ga-N bonded precursor used in a vapor deposition process, was easily synthesized and purified by either sublimation or recrystallisation. Thermogravimetric analysis showed single-step volatilization with an onset temperature of 155 degrees C and negligible residual mass. Three temperature intervals with self-limiting growth were observed when depositing GaN films. The GaN films grown in the second growth interval at 350 degrees C were epitaxial on 4H-SiC without an AlN seed layer and found to have a near stoichiometric Ga/N ratio with very low levels of impurities. In addition, electron microstructure analysis showed a smooth film surface and a sharp interface between the substrate and film. The band gap of these films was 3.41 eV with the Fermi level at 1.90 eV, showing that the GaN films were unintentionally n-type-doped. This new triazenide precursor enables ALD of GaN for semiconductor applications and provides a new Ga(III) precursor for future deposition processes.

  • 36.
    Salamania, Janella
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Johnson, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten. Sandvik Coromant, Sweden.
    Schramm, I. C.
    Sandvik Coromant, Sweden.
    Calamba, K. M.
    Sandvik Coromant, Sweden.
    Boyd, Robert
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Plasma och ytbeläggningsfysik. Linköpings universitet, Tekniska fakulteten.
    Bakhit, Babak
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Rogström, Lina
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Influence of pulsed-substrate bias duty cycle on the microstructure and defects of cathodic arc-deposited Ti1-xAlxN coatings2021Inngår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 419, artikkel-id 127295Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The influence of pulsed substrate bias duty cycle on the growth, microstructure, and defects of Ti1-xAlxN coatings grown by cathodic arc deposition was investigated. Ti1-xAlxN coatings of varying compositions (x = 0.56, 0.38, 0.23) were deposited on cemented carbide substrates with 10, 25, 50, and 95% duty cycles of 50 V pulsed-bias under 10 Pa of pure N-2 gas. Coatings grown at low duty cycles (10 and 25%) showed strongly textured, underdense coatings with facetted columns and low amount of lattice defects. Applying higher duty cycles (50 and 95%) produced coatings that have denser microstructures, less preferred orientation, increasing compressive stresses and increased lattice defect densities. Our study elucidates how duty cycle variation not only changes the overall average energy supplied at the growth front but also kinetically influences the coating growth and thus microstructure and defect structure.

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  • 37.
    Salamania, Janella
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Sangiovanni, Davide Giuseppe
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Kraych, A.
    The Interdisciplinary Centre for Advanced Materials Simulation (ICAMS), Ruhr-Universität Bochum, Bochum, Germany.
    Calamba Kwick, K.M.
    Sandvik Coromant AB, Stockholm, Sweden.
    Schramm, I.C.
    Sandvik Coromant AB, Stockholm, Sweden.
    Johnson, L.J.S.
    Sandvik Coromant AB, Stockholm, Sweden.
    Boyd, Robert
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Plasma och ytbeläggningsfysik. Linköpings universitet, Tekniska fakulteten.
    Bakhit, Babak
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Hsu, Tun-Wei
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Mrovec, M.
    The Interdisciplinary Centre for Advanced Materials Simulation (ICAMS), Ruhr-Universität Bochum, Bochum, Germany.
    Rogström, Lina
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Tasnadi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Abrikosov, Igor A.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Elucidating dislocation core structures in titanium nitride through high-resolution imaging and atomistic simulations2022Inngår i: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 224, artikkel-id 111327Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Although titanium nitride (TiN) is among the most extensively studied and thoroughly characterizedthin-film ceramic materials, detailed knowledge of relevant dislocation core structures is lacking. Byhigh-resolution scanning transmission electron microscopy (STEM) of epitaxial single crystal (001)-oriented TiN films, we identify different dislocation types and their core structures. These include, besidesthe expected primary a/2{110}h110i dislocation, Shockley partial dislocations a/6{111}h112i and sessileLomer edge dislocations a/2{100}h011i. Density-functional theory and classical interatomic potentialsimulations complement STEM observations by recovering the atomic structure of the different disloca-tion types, estimating Peierls stresses, and providing insights on the chemical bonding nature at the core.The generated models of the dislocation cores suggest locally enhanced metal–metal bonding, weakenedTi-N bonds, and N vacancy-pinning that effectively reduces the mobilities of {110}h110i and {111}h112idislocations. Our findings underscore that the presence of different dislocation types and their effects onchemical bonding should be considered in the design and interpretations of nanoscale and macroscopicproperties of TiN.

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  • 38.
    Shu, Rui
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Paschalidou, Eirini-Maria
    Department of Chemistry-Ångström, Uppsala University.
    Gangaprasad Rao, Smita
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Bakhit, Babak
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Boyd, Robert
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Plasma och ytbeläggningsfysik. Linköpings universitet, Tekniska fakulteten.
    Moro, Marcos Vinicius
    Department of Physics and Astronomy, Uppsala University.
    Primetzhofer, Daniel
    Department of Physics and Astronomy, Uppsala University.
    Greczynski, Grzegorz
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Nyholm, Leif
    Department of Chemistry-Ångström, Uppsala University.
    Le Febvrier, Arnaud
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Eklund, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Effect of nitrogen content on microstructure and corrosion resistance of sputter-deposited multicomponent (TiNbZrTa)Nx films2020Inngår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 404, artikkel-id 126485Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Multicomponent (TiNbZrTa)Nx films were deposited on Si(100) substrates at room temperature using magnetron sputtering with a nitrogen flow ratio fN [fN = N2/(Ar + N2)], which was varied from 0 to 30.8%. The nitrogen content in the films varied between 0 and 45.2 at.%, i.e., x = 0 to 0.83. The microstructure was characterized by X-ray diffraction and electron microscopy. The metallic TiNbZrTa film comprised a dominant bcc solid-solution phase, whereas a single NaCl-type face-centred cubic structure was observed in all nitrogen-containing films (TiNbZrTa)Nx. The mechanical, electrical, and electrochemical properties of these films varied with nitrogen content. The maximum hardness was achieved at 22.1 ± 0.3 GPa when N = 43.0 at.%. The resistivities increased from 95 to 424 μΩcm with increasing nitrogen content. A detailed study of the variation of morphology and chemical bonding with nitrogen content was performed and the corrosion resistance of the TiNbZrTa nitride films was explored in 0.1 M H2SO4. While all the films had excellent corrosion resistances at potentials up to 2.0 V vs. Ag/AgCl, the metallic film and the films with low nitrogen contents (x < 0.60) exhibited an almost stable current plateau up to 4.0 V vs. Ag/AgCl. For the films with higher nitrogen contents (x ≥ 0.68), the current plateau was retained up to 2.0 V vs. Ag/AgCl, above which a higher nitrogen content resulted in a higher current. The decrease in the corrosion resistance at these high potentials indicate the presence of a potential-dependent activation effect resulting in an increased oxidation rate of the nitrides (present under the passive oxide film) yielding a release of nitrogen from the films. TEM results indicate that the oxide layer formed after this corrosion measurement was thick and porous for the film with x = 0.76, in very good agreement with the increased corrosion rate for this film. The results demonstrate that an increased nitrogen content in (TiNbZrTa)Nx system improves their mechanical properties with retained high corrosion resistance at potentials up to 2.0 V vs. Ag/AgCl in 0.1 M H2SO4. At even higher potentials, however, the corrosion resistance decreases with increasing nitrogen concentration for films with sufficiently high nitrogen contents (i.e. x ≥ 0.68).

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  • 39.
    Suliali, Nyasha J.
    et al.
    Nelson Mandela Univ, South Africa.
    Goosen, William E.
    Nelson Mandela Univ, South Africa; Nelson Mandela Univ, South Africa.
    van Vuuren, Arno Janse
    Nelson Mandela Univ, South Africa; Nelson Mandela Univ, South Africa.
    Olivier, Ezra J.
    Nelson Mandela Univ, South Africa; Nelson Mandela Univ, South Africa.
    Bakhit, Babak
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Högberg, Hans
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Darakchieva, Vanya
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten.
    Botha, Johannes R.
    Nelson Mandela Univ, South Africa.
    Ti thin films deposited by high-power impulse magnetron sputtering in an industrial system: Process parameters for a low surface roughness2022Inngår i: Vacuum, ISSN 0042-207X, E-ISSN 1879-2715, Vol. 195, artikkel-id 110698Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The influence of the choice of process parameters in an industrial high-power impulse magnetron sputtering (HiPIMS) system on the surface roughness and crystallinity of Ti coatings is presented in this work. A current density of 1 A/cm(2) was kept constant by varying the pulse frequency to control the average power. The films were characterised by scanning electron microscopy, atomic force microscopy, X-ray diffraction and transmission electron microscopy. The surface roughness, residual stress and grain size are discussed as a function of the HiPIMS target average power in the 1.45-7.90 kW range. The surface roughness, ranging from 14 to 24 nm, is lower than that of the SnO2 glass substrate, and has a non-linear dependence on the HiPIMS power. X-ray 20 diffraction shows (100), (001) and (101) orientation of the film crystallites. The peak shifts reveal a gradual reduction in residual stress as target power increases. Further, the effect of target power on crystal grain length and geometric orientation is also determined.

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  • 40.
    Thörnberg, Jimmy
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Bakhit, Babak
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Palisaitis, Justinas
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Hellgren, Niklas
    Messiah Univ, PA 17055 USA.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Greczynski, Grzegorz
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Persson, Per O Å
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Petrov, Ivan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. Univ Illinois, IL 61801 USA; Univ Illinois, IL 61801 USA; Natl Taiwan Univ Sci & Technol, Taiwan.
    Rosén, Johanna
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Improved oxidation properties from a reduced B content in sputter-deposited TiBx thin films2021Inngår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 420, artikkel-id 127353Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Transition-metal diboride thin films, which have high melting points, excellent hardness, and good chemical and thermal conductivity, severely suffer from rapid oxidation in air. Here, we explore the influence of varying B content and resulting nanostructure change on the oxidation properties of TiBx thin films, with x = 1.43, 2.20, and 2.70. Results show that all as-deposited layers have columnar structure. The column boundaries of asdeposited TiB2.20 and TiB2.20 films grown by direct current magnetron sputtering (DCMS) are B-rich, while the as-deposited TiB1.43 films grown by high-power impulse magnetron sputtering (HiPIMS) show no apparent grain boundary phases and contain Ti-rich planar defects. The oxidation rate of TiBL43 air-annealed at 400 degrees C up to 48 h is significantly lower than that of TiB2.20 and TiB2.20 films. The oxidation rate of TiB1.43, TiB2.20, and TiB2.20 films was measured at 2.9 +/- 1.5, 7.1 +/- 1.0, and 20.0 +/- 5.0 nm/h, respectively, with no spallation of even as thick oxide scales as 0.5 mu m in any of the films. The improved oxidation resistance can be explained by the absence of B-rich tissue phase at the column boundaries of understoichiometric TiBx films, a phase that interlaces the nanocolumnar TiB2 structures in the corresponding overstoichiometric films. An easy oxidation pathway is thus eliminated.

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  • 41.
    Thörnberg, Jimmy
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Materialdesign. Linköpings universitet, Tekniska fakulteten.
    Mraz, Stanislav
    Palisaitis, Justinas
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Klimashin, Fedor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Materialdesign. Linköpings universitet, Tekniska fakulteten.
    Ondracka, Pavel
    Rhein Westfal TH Aachen, Germany.
    Bakhit, Babak
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Polcik, Peter
    Plansee Composite Mat GmbH, Germany.
    Kolozsvari, Szilard
    Plansee Composite Mat GmbH, Germany.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Petrov, Ivan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. Univ Illinois, IL 61801 USA; Natl Taiwan Univ Sci & Technol, Taiwan.
    Persson, Per O A
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Schneider, Jochen M.
    Rhein Westfal TH Aachen, Germany.
    Rosén, Johanna
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Materialdesign. Linköpings universitet, Tekniska fakulteten.
    Oxidation resistance and mechanical properties of sputter-deposited Ti0.9Al0.1B2-y thin films2022Inngår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 442, artikkel-id 128187Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Direct-current magnetron sputtering (DCMS) and high-power impulse magnetron sputtering (HiPIMS) were used to deposit understoichiometric Ti(1-x)Al(x)B(2-y )diboride coatings by sputtering from a segmented TiB2-AlB2 target using Ar and Kr as sputtering gas. For films with a fixed Al/(Ti + Al) ratio of x = 0.1 (Ti0.9Al0.1B2-y), the B content was varied with y & ISIN; (0.1, 0.6 and 0.7). For films with a fixed y = 0.7 (Ti1-xAlxB1.3), the Al content was varied with x & ISIN; (0.1, 0.4 and 0.7). Evaluation of the mechanical properties of the Ti1-xAlxB1.3 samples showed a reduction in both hardness and elastic modulus with increasing Al concentration, while the Ti0.9Al0.1B2-y samples showed a hardness increase with decreasing B content. Thus, Ti0.9Al0.1B1.3 films exhibited a superior hardness of 46.2 +/- 1.1 GPa and an elastic modulus of 523 & PLUSMN; 7 GPa, compared to the values for Ti0.9Al0.1B1.4 and Ti0.9Al0.1B1.9, showing a hardness of 44 +/- 1 GPa and 36 +/- 1 GPa, and an elastic modulus of 569 +/- 7 GPa and 493 +/- 6 GPa, respectively. The oxidation behavior of the mechanically most promising Ti0.9Al0.1B2-y sample series was investigated through air-annealing at 600 C for durations from 1 h to 10 h. All films formed a mixed non-conformal Al2O3-TiO2 oxide scale which acts as an inward and outward diffusion barrier, significantly reducing the oxidation rate compared to TiBz films, which form an oxide scale consisting of porous TiO2. The thinnest oxide scale after 10 h was found in the B-deficient samples, Ti0.9Al0.1B1.3 and Ti0.9Al0.1B1.4, at ~200 nm, which is significantly below that for Ti0.9Al0.1B1.9 at 320 nm. The enhanced oxidation resistance of highly understoichiometric films is due to the elimination of the B-rich tissue phase that is present at the grain boundaries for higher B content, where the latter has been shown to enhance the rate of oxidation in borides.

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  • 42.
    Wells, Matthew P.
    et al.
    Univ Cambridge, England.
    Lovett, Adam J.
    Univ Cambridge, England.
    Zhang, Yizhi
    Purdue Univ, IN 47907 USA.
    Shang, Zhongxia
    Purdue Univ, IN 47907 USA.
    Kreka, Kosova
    Catalonia Inst Energy Res IREC, Spain.
    Bakhit, Babak
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. Univ Cambridge, England; Univ Cambridge, England.
    Wang, Haiyan
    Purdue Univ, IN 47907 USA.
    Tarancon, Albert
    Catalonia Inst Energy Res IREC, Spain; ICREA, Spain.
    MacManus-Driscoll, Judith L.
    Univ Cambridge, England.
    Pathway to high performance, low temperature thin-film solid oxide cells grown on porous anodised aluminium oxide2024Inngår i: Nano Energy, ISSN 2211-2855, E-ISSN 2211-3282, Vol. 119, artikkel-id 109049Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Reversible solid oxide cells (rSOCs) present a promising solution to future energy challenges through the efficient conversion between electrical and chemical energy. To date, the benefits of rSOC technology have been off-limits to portable power and electrolysis applications due to the excessive polarisation resistance of the oxygen electrode at low temperatures, characterised by high area specific resistance (ASR) values below 500 degrees C. In this work we demonstrate growth of symmetric and complete rSOC structures based on state-of-the-art vertically aligned nanocomposite (VAN) films grown by pulsed laser deposition (PLD) on porous Pt-coated anodised aluminium oxide (AAO) substrates. The symmetric rSOC structures give the first demonstration of an rSOC oxygen electrode with ASR below 0.1 ohm cm2 at temperatures less than 450 degrees C. This is achieved through oxygen vacancy tuning by annealing, as confirmed by Time-of-Flight Elastic Recoil Detection Analysis (ToF-ERDA) and Rutherford Backscattering Spectrometry (RBS) measurements. Thus, the present work describes a promising route towards future high-performance rSOC devices for portable power applications.

  • 43.
    Wicher, Bartosz
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. Warsaw Univ Technol, Poland.
    Pshyk, Oleksandr
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. Empa Swiss Fed Labs Mat Sci & Technol, Switzerland.
    Li, Xiao
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Bakhit, Babak
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Rogoz, Vladyslav
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Petrov, Ivan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. Univ Illinois, IL 61801 USA.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Greczynski, Grzegorz
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Superhard oxidation-resistant Ti1-xAlxBy thin films grown by hybrid HiPIMS/DCMS co-sputtering diboride targets without external substrate heating2024Inngår i: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 238, artikkel-id 112727Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ti1-xAlxBy films (0.40 &lt;= x &lt;= 0.76, and 1.81 &lt;= y &lt;= 2.03) combining good mechanical properties and high-temperature oxidation resistance are demonstrated. Layers are grown using a hybrid high-power impulse and dc magnetron co-sputtering employing two target configurations (AlB2-HiPIMS/TiB2-DCMS and TiB2-HiPIMS/AlB2-DCMS) and no external substrate heating. Near-stoichiometric B content are achieved by co-sputtering two diboride targets. Time-resolved ion mass spectrometry analyses reveal that the ionization of the DCMS flux (Al) is much higher during TiB2-HiPIMS/AlB2-DCMS. The effect is caused by the difference in the first ionization potentials and the ionization probabilities of sputtered metals and results in lower B/metal ratios in films grown in this configuration. The B/metal ratio in the single-phase Ti1-xAlxBy decreases with increasing Al content, which is explained by the change between angular distribution of Ti and Al atoms. Alloying with Al improves the high-temperature oxidation resistance: the thickness of the oxide-scale forming after 1 h anneal at 800 degrees C decreases more than 15 times upon increasing x from 0.36 to 0.74. Ti1-xAlxBy films with 0.58 &lt;= x &lt;= 0.67 offer the best compromise between high-temperature oxidation resistance and mechanical properties with an average oxide scale thickness 90-180 nm and the hardness of 34-38 GPa.

  • 44.
    Wu, Zhengtao
    et al.
    Guangdong Univ Technol, Peoples R China.
    Tengstrand, Olof
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Bakhit, Babak
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Lu, Jun
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Greene, Joseph E
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. Univ Illinois, IL 61801 USA; Natl Taiwan Univ Sci and Technol, Taiwan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Petrov, Ivan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. Univ Illinois, IL 61801 USA.
    Greczynski, Grzegorz
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Growth of dense, hard yet low-stress Ti0.40Al0.27W0.33N nanocomposite films with rotating substrate and no external substrate heating2020Inngår i: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 38, nr 2Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    W+ irradiation of TiAlN is used to demonstrate growth of dense, hard, and stress-free refractory nitride coatings with no external heating during reactive magnetron sputtering. Ti0.40Al0.27W0.33N nanocomposite films are deposited on Si(001) substrates using hybrid high-power impulse and dc magnetron cosputtering (HiPIMS and DCMS) in an industrial sputtering system employing substrate rotation during film growth from six cathodes. Two W targets powered by HiPIMS serve as a pulsed source of energetic W+ ions with incident fluxes analyzed by in situ time- and energy-resolved mass spectroscopy, while the remaining four targets (two elemental Ti targets and two Ti plates with Al plugs) are operated in the DCMS mode (W-HiPIMS/TiAl-DCMS) to provide a continuous flux of metal atoms and sustain a high deposition rate. A negative substrate bias V-s is applied only in synchronous with the W+-ion-rich portion of each HiPIMS pulse in order to provide film densification by heavy-ion irradiation of the TiAlN layers deposited between W+-ion exposures. W is selected for densification due to its high mass and relatively low reactivity with N-2, thus minimizing target poisoning while enhancing gas rarefaction. Dense Ti0.40Al0.27W0.33N alloy films, grown with no external substrate heating (substrate temperature T-s lower than 150 degrees C due to heat load from the plasma) and V-s=500V, exhibit a nanoindentation hardness of H=23.1GPa and an elastic modulus of E=378GPa, which are, respectively, 210% and 40% higher than for reference underdense DCMS Ti0.58Al0.42N films grown under the same conditions, but without W+ irradiation. The W ion bombardment does not affect the film stress state, which is compressive and low at 1.2GPa.

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  • 45.
    Wu, Zhengtao
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. Guangdong Univ Technol, Peoples R China.
    Ye, Rongli
    Guangdong Univ Technol, Peoples R China.
    Bakhit, Babak
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Petrov, Ivan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. Univ Illinois, IL 61801 USA; Natl Taiwan Univ Sci & Technol, Taiwan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Greczynski, Grzegorz
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Improving oxidation and wear resistance of TiB2 films by nano-multilayering with Cr2022Inngår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 436, artikkel-id 128337Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Alternating TiB2-DCMS and Cr-HiPIMS layers are used to fabricate TiB2/Cr multilayer films with varying the Cr-interlayer thickness, 2 and 5 nm, and the substrate bias during growth of Cr interlayers from floating, to -60 V and -200 V. The effects of multilayer structure on mechanical properties, static oxidation, and tribological behavior of the TiB2/Cr multilayers are investigated. The results reveal that TiB2 nanocolumns renucleate at each Cr interface maintaining smooth film surface and film density. Interlaying with Cr with thicknesses of 2-5 nm improves the resistance to oxidation at 500-600 ?& nbsp;as compared to TiB2 monolayer. The increase of the thickness of the Cr interlayers from 2 to 5 nm decreases the hardness of the multilayer slightly but deteriorates the wear rate significantly. The friction coefficients at 500 ?& nbsp;are lower than those at RT due to boric acid liquid lubrication induced by surface oxidation. The TiB2/Cr multilayer films show higher wear resistance than TiB2 monolayer. The multilayer films with 2 nm-thick Cr deposited at -60 V have the lowest recorded wear rates. Irradiation with 200 eV Cr+ leads to interface mixing, resulting in the formation of B-deficient TiBx phase (x &lt; 2) and higher wear rates compared to multilayers grown at -60 V.

    Fulltekst (pdf)
    fulltext
  • 46.
    Wu, Zhengtao
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. Guangdong Univ Technol, Peoples R China.
    Ye, Rongli
    Guangdong Univ Technol, Peoples R China.
    Bakhit, Babak
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Petrov, Ivan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. Univ Illinois, IL 61801 USA; Natl Taiwan Univ Sci & Technol, Taiwan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Greczynski, Grzegorz
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Reprint of: Improving oxidation and wear resistance of TiB2 films by nano-multilayering with Cr*2022Inngår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 442, artikkel-id 128602Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Alternating TiB2-DCMS and Cr-HiPIMS layers are used to fabricate TiB2/Cr multilayer films with varying the Cr interlayer thickness, 2 and 5 nm, and the substrate bias during growth of Cr interlayers from floating, to -60 V and -200 V. The effects of multilayer structure on mechanical properties, static oxidation, and tribological behavior of the TiB2/Cr multilayers are investigated. The results reveal that TiB2 nanocolumns renucleate at each Cr interface maintaining smooth film surface and film density. Interlaying with Cr with thicknesses of 2-5 nm improves the resistance to oxidation at 500-600 degrees C as compared to TiB2 monolayer. The increase of the thickness of the Cr interlayers from 2 to 5 nm decreases the hardness of the multilayer slightly but deteriorates the wear rate significantly. The friction coefficients at 500 degrees C are lower than those at RT due to boric acid liquid lubrication induced by surface oxidation. The TiB2/Cr multilayer films show higher wear resistance than TiB2 monolayer. The multilayer films with 2 nm-thick Cr deposited at -60 V have the lowest recorded wear rates. Irradiation with 200 eV Cr+ leads to interface mixing, resulting in the formation of B-deficient TiBx phase (x &lt; 2) and higher wear rates compared to multilayers grown at -60 V.

  • 47.
    Wu, Zhixing
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Vagin, Mikhail
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Laboratoriet för organisk elektronik. Linköpings universitet, Tekniska fakulteten.
    Boyd, Robert
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Plasma och ytbeläggningsfysik. Linköpings universitet, Tekniska fakulteten.
    Bakhit, Babak
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Greczynski, Grzegorz
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Björk, Emma
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Morphology effects on electrocatalysis of anodic water splitting on nickel (II) oxide2022Inngår i: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 333, artikkel-id 111734Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Oxygen evolution reaction (OER) is critical for producing high purity hydrogen and oxygen via electrocatalytic water splitting. In this work, single crystalline, nanoporous nickel oxide (NiO) was prepared using a hydro thermal, soft-templated synthesis route followed by calcination at different temperatures. It is shown that the NiO crystals have a cubic lattice, and the pore size can be tuned from similar to 1 to similar to 70 nm by varying the calcination temperature, i.e. variation from micro to macroporosity. The NiOs catalytic performance as electrocatalysts was evaluated in OER, both thermodynamically and kinetically. Mesoporous NiO with calcination temperature of 400 degrees C had the lowest overpotential (335 mV) required @ 10 mA/cm(2) accompanied with the highest turnover frequency value and mass activity among of the obtained NiO electrocatalysts. The study shows that the electrocatalytic activity of nanoporous NiO outperforms that of commercial catalyst Ir/C (similar to 360 mV @ 10 mA/cm(2)). Microporous NiO possess the highest specific surface area and electrical double layer capacitance, while the nonporous NiO particles have the highest specific activity and BET activity of the catalysts. It is concluded that the minimization of voltage losses by the nanoscale enlargement of the electrocatalyst surface area shows the coherence between gas adsorption and electrocapacitive measurements. Conversely, the OER kinetics showed deterioration with surface area maximization due to the impediment of ionic transport inside the micropores. This work demonstrates the importance of morphology optimization to obtain an efficient OER electrocatalyst with low required overpotential and kinetic loss.

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