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Dorri, S., Ghafoor, N., Palisaitis, J., Stendahl, S., Devishvili, A., Vorobiev, A., . . . Birch, J. (2024). Enhanced quality of single crystal CrBx/TiBy diboride superlattices by controlling boron stoichiometry during sputter deposition. Applied Surface Science, Article ID 159606.
Open this publication in new window or tab >>Enhanced quality of single crystal CrBx/TiBy diboride superlattices by controlling boron stoichiometry during sputter deposition
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2024 (English)In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, article id 159606Article in journal (Refereed) Published
Abstract [en]

Single-crystal CrB2/TiB2 diboride superlattices with well-defined layers are promising candidates for neutron optics. However, excess B in sputter-deposited TiBy using a single TiB2 target deteriorates the structural quality of CrBx/TiBy (0001) superlattices. We study the influence of co-sputtering of TiB2 + Ti on the stoichiometry and crystalline quality of 300-nm-thick TiBy single layers and CrBx/TiBy (0001) superlattices on Al2O3(0001) substrates grown by DC magnetron sputter epitaxy at growth-temperatures TS ranging from 600 to 900 °C. By controlling the relative applied powers to the TiB2 and Ti magnetrons, y could be reduced from 3.3 to 0.9. TiB2.3 grown at 750 °C exhibited epitaxial domains about 10x larger than non-co-sputtered films. Close-to-stoichiometry CrB1.7/TiB2.3 superlattices with modulation periods Λ = 6 nm grown at 750 °C showed the highest single crystal quality and best layer definition. TiB2.3 layers display rough top interfaces indicating kinetically limited growth while CrB1.7 forms flat and abrupt top interfaces indicating epitaxial growth with high adatom mobility.

Place, publisher, year, edition, pages
Elsevier, 2024
Keywords
Superlattice, Diboride, Thin film, Co-sputtering, Nanostructure
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:liu:diva-200730 (URN)10.1016/j.apsusc.2024.159606 (DOI)001183388000001 ()
Note

Funding: Swedish National Graduate School in Neutron Scattering (SwedNess), Swedish Foundation for Strategic Research (SSF) GSn15 - 0008, Swedish Government Strategic Research Area in Materials Science on Advanced Functional Materials (AFM) at Linköping University (Faculty Grant SFO Mat LiU No. 2009 00971), Center in Nanoscience and technology at LiTH CeNano, Hans Werthén Foundation (IVA), Society of Vacuum Coaters Foundation (SVCF), Swedish Research Council (VR) Grant numbers 2019-00191 (for accelerator-based ion-technological center in tandem accelerator laboratory in Uppsala University), VR and SSF for access to ARTEMI, the Swedish National Infrastructure in Advanced Electron Microscopy (2021-00171 and RIF21-0026), Knut and Alice Wallenberg Foundation for the support of the electron microscopy laboratory at Linköping University (KAW 2015.0043), VR 2021-00159 for the Swedish neutron reflectometer SuperADAM at ILL 10.5291/ILL-DATA.CRG-2964, and Plansee GmbH for providing diboride targets.

Available from: 2024-02-06 Created: 2024-02-06 Last updated: 2024-04-12Bibliographically approved
Chang, J.-C., Tseng, E. N., Lo, Y.-L., Nayak, S. K., Lundin, D., Persson, P. O. Å., . . . Hsiao, C.-L. (2023). HiPIMS-grown AlN buffer for threading dislocation reduction in DC-magnetron sputtered GaN epifilm on sapphire substrate. Vacuum, 217, Article ID 112553.
Open this publication in new window or tab >>HiPIMS-grown AlN buffer for threading dislocation reduction in DC-magnetron sputtered GaN epifilm on sapphire substrate
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2023 (English)In: Vacuum, ISSN 0042-207X, E-ISSN 1879-2715, Vol. 217, article id 112553Article in journal (Refereed) Published
Abstract [en]

Gallium nitride (GaN) epitaxial films on sapphire (Al2O3) substrates have been grown using reactive magnetron sputter epitaxy with a liquid Ga target. Threading dislocations density (TDD) of sputtered GaN films was reduced by using an inserted high-quality aluminum nitride (AlN) buffer layer grown by reactive high power impulse magnetron sputtering (R-HiPIMS) in a gas mixture of Ar and N2. After optimizing the Ar/N2 pressure ratio and deposition power, a high-quality AlN film exhibiting a narrow full-width at half-maximum (FWHM) value of the double-crystal x-ray rocking curve (DCXRC) of the AlN(0002) peak of 0.086° was obtained by R-HiPIMS. The mechanism giving rise the observed quality improvement is attributed to the enhancement of kinetic energy of the adatoms in the deposition process when operated in a transition mode. With the inserted HiPIMS-AlN as a buffer layer for direct current magnetron sputtering (DCMS) GaN growth, the FWHM values of GaN(0002) and (10 1‾ 1) XRC decrease from 0.321° to 0.087° and from 0.596° to 0.562°, compared to the direct growth of GaN on sapphire, respectively. An order of magnitude reduction from 2.7 × 109 cm−2 to 2.0 × 108 cm−2 of screw-type TDD calculated from the FWHM of the XRC data using the inserted HiPIMS-AlN buffer layer demonstrates the improvement of crystal quality of GaN. The result of TDD reduction using the HiPIMS-AlN buffer was also verified by weak beam dark-field (WBDF) cross-sectional transmission electron microscopy (TEM).

Place, publisher, year, edition, pages
PERGAMON-ELSEVIER SCIENCE LTD, 2023
Keywords
GaN; Magnetron sputtering; HiPIMS; Dislocations; XRCTEM
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:liu:diva-197990 (URN)10.1016/j.vacuum.2023.112553 (DOI)001072124300001 ()
Funder
Swedish Research CouncilSwedish Energy AgencyThe Swedish Foundation for International Cooperation in Research and Higher Education (STINT)Carl Tryggers foundation Olle Engkvists stiftelse
Note

Funding agencies: This research was funded by Vetenskapsrådet (grant number 2018-04198), Energimyndigheten (grant number 46658-1), Carl Tryggers Stiftelse (grant number CTS 22:2029) and Stiftelsen Olle Engkvist Byggmästare (grant number 197-0210). The Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linköping University (Faculty Grant SFO-Mat-LiU 2009-00971) is acknowledged for financial support. We acknowledge STINT foundation, Sweden, for supporting this international collaboration (grant number: MG2019-8485).

Available from: 2023-09-20 Created: 2023-09-20 Last updated: 2023-12-21
Zheng, W., Halim, J., Persson, P., Rosén, J. & Barsoum, M. (2022). Effect of vacancies on the electrochemical behavior of Mo-based MXenes in aqueous supercapacitors. Journal of Power Sources, 525, Article ID 231064.
Open this publication in new window or tab >>Effect of vacancies on the electrochemical behavior of Mo-based MXenes in aqueous supercapacitors
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2022 (English)In: Journal of Power Sources, ISSN 0378-7753, E-ISSN 1873-2755, Vol. 525, article id 231064Article in journal (Refereed) Published
Abstract [en]

i-MXenes, a new family of 2D transition metal carbides with in-plane ordered vacancies, have shown great potential in aqueous supercapacitor (SC) applications due to their high volumetric capacitances and energy densities. However, how vacancies affect their electrochemical performance, in general, and their self-discharge (SD) behavior in particular, remains unexplored. Herein, we compare the electrochemical performance of vacancy rich, ordered Mo1.33CTz i-MXene to that of Mo2CTz (with much less vacancies) in a 1 M sulfuric acid (H2SO4) or 15 M of lithium bromide (LiBr) electrolyte. The Mo1.33CTz exhibits higher volumetric capacitances and energy densities, but at the cost of a higher SD rate. Specifically, the Mo1.33CTz symmetric SCs deliver an energy density as high as 25.4 mWh cm(-3) at 152.4 mW cm-3, with 65.4% voltage retention after 10 h in 15 M LiBr. In comparison, the Mo2CTz symmetric SCs have a maximum energy density of 20.8 mWh cm-3 at 124.9 mW cm-3, with 73.1% voltage retention after 10 h in the same electrolyte. The SD rates in the H2SO4 electrolyte are quite rapid.

Place, publisher, year, edition, pages
Amsterdam, Netherlands: Elsevier, 2022
Keywords
MXene; i -MXene; Supercapacitor; Vacancies; High-concentrated electrolyte; Self-discharge
National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:liu:diva-184844 (URN)10.1016/j.jpowsour.2022.231064 (DOI)000781812100003 ()2-s2.0-85124097173 (Scopus ID)
Note

Funding Agencies: Swedish Foundation for Strategic Research [EM16-0004]; Knut and Alice Wallenberg (KAW) foundation for a Fellowship/Scholar grant; Swedish Foundation for Strategic Research (SSF) through the Research Infrastructure Fellow program; [RIF 14-0074]

Available from: 2022-05-13 Created: 2022-05-13 Last updated: 2024-01-10Bibliographically approved
Ekström, E., Elsukova, A., Grasland, J., Palisaitis, J., Ramanath, G., Persson, P., . . . Eklund, P. (2022). Epitaxial Growth of CaMnO3-y Films on LaAlO3 (112 over bar 0) by Pulsed Direct Current Reactive Magnetron Sputtering. Physica Status Solidi. Rapid Research Letters, 16(4), Article ID 2100504.
Open this publication in new window or tab >>Epitaxial Growth of CaMnO3-y Films on LaAlO3 (112 over bar 0) by Pulsed Direct Current Reactive Magnetron Sputtering
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2022 (English)In: Physica Status Solidi. Rapid Research Letters, ISSN 1862-6254, E-ISSN 1862-6270, Vol. 16, no 4, article id 2100504Article in journal (Refereed) Published
Abstract [en]

CaMnO3 is a perovskite with attractive magnetic and thermoelectric properties. CaMnO3 films are usually grown by pulsed laser deposition or radio frequency magnetron sputtering from ceramic targets. Herein, epitaxial growth of CaMnO3-y (002) films on a (112 over bar 0)-oriented LaAlO3 substrate using pulsed direct current reactive magnetron sputtering is demonstrated, which is more suitable for industrial scale depositions. The CaMnO3-y shows growth with a small in-plane tilt of <approximate to 0.2 degrees toward the (200) plane of CaMnO3-y and the (1 over bar 104) with respect to the LaAlO3 (112 over bar 0) substrate. X-ray photoelectron spectroscopy of the electronic core levels shows an oxygen deficiency described by CaMnO2.58 that yields a lower Seebeck coefficient and a higher electrical resistivity when compared to stoichiometric CaMnO3. The LaAlO3 (112 over bar 0) substrate promotes tensile-strained growth of single crystals. Scanning transmission electron microscopy and electron energy loss spectroscopy reveal antiphase boundaries composed of Ca on Mn sites along and , forming stacking faults.

Place, publisher, year, edition, pages
Wiley-V C H Verlag GMBH, 2022
Keywords
CaMnO3; epitaxy; perovskites; PVD
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:liu:diva-182501 (URN)10.1002/pssr.202100504 (DOI)000741329200001 ()
Note

Funding Agencies|Swedish Research Council (VR)Swedish Research Council [2016-03365]; Knut and Alice Wallenberg Foundation through the Wallenberg Academy Fellows program [KAW 2020.0196]; Electron Microscopy Laboratory at Linkoping University; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO-Mat-LiU) [2009 00971]; Swedish Energy AgencySwedish Energy AgencyMaterials & Energy Research Center (MERC) [46519-1]; Swedish Foundation for Strategic Research (SSF)Swedish Foundation for Strategic Research [RIF 14-0074]

Available from: 2022-01-26 Created: 2022-01-26 Last updated: 2023-05-09Bibliographically approved
Gogova, D., Ghezellou, M., Tran, D. Q., Richter, S., Papamichail, A., ul-Hassan, J., . . . Darakchieva, V. (2022). Epitaxial growth of β-Ga2O3 by hot-wall MOCVD. AIP Advances, 12(5), Article ID 055022.
Open this publication in new window or tab >>Epitaxial growth of β-Ga2O3 by hot-wall MOCVD
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2022 (English)In: AIP Advances, E-ISSN 2158-3226, Vol. 12, no 5, article id 055022Article in journal (Refereed) Published
Abstract [en]

The hot-wall metalorganic chemical vapor deposition (MOCVD) concept, previously shown to enable superior material quality and high performance devices based on wide bandgap semiconductors, such as Ga(Al)N and SiC, has been applied to the epitaxial growth of beta-Ga2O3. Epitaxial beta-Ga2O3 layers at high growth rates (above 1 mu m/h), at low reagent flows, and at reduced growth temperatures (740 degrees C) are demonstrated. A high crystalline quality epitaxial material on a c-plane sapphire substrate is attained as corroborated by a combination of x-ray diffraction, high-resolution scanning transmission electron microscopy, and spectroscopic ellipsometry measurements. The hot-wall MOCVD process is transferred to homoepitaxy, and single-crystalline homoepitaxial beta-Ga2O3 layers are demonstrated with a 201 rocking curve width of 118 arc sec, which is comparable to those of the edge-defined film-fed grown (201) beta-Ga2O3 substrates, indicative of similar dislocation densities for epilayers and substrates. Hence, hot-wall MOCVD is proposed as a prospective growth method to be further explored for the fabrication of beta-Ga2O3.

Place, publisher, year, edition, pages
AIP Publishing, 2022
National Category
Condensed Matter Physics
Identifiers
urn:nbn:se:liu:diva-185208 (URN)10.1063/5.0087571 (DOI)000797911600007 ()
Funder
Swedish Energy Agency, P45396-1Vinnova, 2016-05190Swedish Research Council, 2016-00889Swedish Research Council, 2017-03714Knut and Alice Wallenberg Foundation, 2018.0071
Note

Funding: Swedish Energy Agency [P45396-1]; Swedish Governmental Agency for Innovation Systems (VINNOVA) [2016-05190]; Ericsson; Gotmic; Swedish Research Council VR [2016-00889, 2017-03714]; Swedish Foundation for Strategic Research [RIF14-055, RIF14-074, EM16-0024]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University; SFO Mat LiU [2009-00971]; National Science Foundation (NSF); NSF [DMR 1808715]; Linkoeping University [OIA-2044049]; NSF/EPSCoR RII Track-1: Emergent Quantum Materials and Technologies (EQUATE); Chalmers University of Technology [FA9550-18-1-0360, FA9550-19-S-0003, FA9550-21-1-0259]; Air Force Office of Scientific Research; Epiluvac; KAW Foundation; FMV; Hexagem; Hitachi Energy; On Semiconductor; Saab; SweGaN; UMS

Available from: 2022-05-18 Created: 2022-05-18 Last updated: 2023-03-28Bibliographically approved
Zheng, W., Halim, J., Yang, L., Badr, H. O., Sun, Z., Persson, P., . . . Barsoum, M. (2022). MXene//MnO2 Asymmetric Supercapacitors with High Voltages and High Energy Densities. Batteries & Supercaps, 5(10), Article ID e202200151.
Open this publication in new window or tab >>MXene//MnO2 Asymmetric Supercapacitors with High Voltages and High Energy Densities
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2022 (English)In: Batteries & Supercaps, E-ISSN 2566-6223, Vol. 5, no 10, article id e202200151Article in journal (Refereed) Published
Abstract [en]

Aqueous asymmetric supercapacitors (AASCs) can have high voltages and high energy densities. However, the rational design of AASCs with proper negative and positive electrodes remains a challenge. Herein, we report on an AASC using Mo1.33CTz MXene films as the negative electrode, and tetramethylammonium cation intercalated birnessite (TMA(+)-MnO2) films as the positive electrode in a 21 mol kg(-1) lithium bis(trifluoromethanesulphonyl)imide (LiTFSI) electrolyte. Benefiting from a high, stable voltage of 2.5 V, an energy density of 86.5 Wh L-1 at 2 mV s(-1) and a power density of 10.3 kW L-1 at 1 Vs(-1) were achieved. The cells also exhibit excellent cycling stability (>98% after 1,0000 cycles at 100 mV s(-1)) and a 51.1 % voltage retention after 10 h. This good performance is attributed to the high stable potential window and high volumetric capacitances of both Mo1.33CTz and TMA(+)-MnO2 electrodes in highly concentrated electrolytes. This work provides a roadmap for developing high performance AASCs with high voltages and high energy/power densities, with relatively slow self-discharge rates.

Place, publisher, year, edition, pages
Wiley-V C H Verlag GMBH, 2022
Keywords
birnessite MnO2; high energy density; high voltage; MXene; supercapacitors
National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:liu:diva-186499 (URN)10.1002/batt.202200151 (DOI)000810453000001 ()
Note

Funding Agencies|Swedish Foundation for Strategic Research (SSF) [EM16-0004]; Knut and Alice Wallenberg (KAW) foundation; Swedish Foundation for Strategic Research (SSF) through the Research Infrastructure Fellow program [RIF 14-0074]

Available from: 2022-06-29 Created: 2022-06-29 Last updated: 2024-01-10Bibliographically approved
Shu, R., Han, Z., Elsukova, A., Zhu, Y., Qin, P., Jiang, F., . . . Liu, W. (2022). Solid-State Janus Nanoprecipitation Enables Amorphous-Like Heat Conduction in Crystalline Mg3Sb2-Based Thermoelectric Materials. Advanced Science, 9(25), Article ID 2202594.
Open this publication in new window or tab >>Solid-State Janus Nanoprecipitation Enables Amorphous-Like Heat Conduction in Crystalline Mg3Sb2-Based Thermoelectric Materials
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2022 (English)In: Advanced Science, E-ISSN 2198-3844, Vol. 9, no 25, article id 2202594Article in journal (Refereed) Published
Abstract [en]

Solid-state precipitation can be used to tailor material properties, ranging from ferromagnets and catalysts to mechanical strengthening and energy storage. Thermoelectric properties can be modified by precipitation to enhance phonon scattering while retaining charge-carrier transmission. Here, unconventional Janus-type nanoprecipitates are uncovered in Mg3Sb1.5Bi0.5 formed by side-by-side Bi- and Ge-rich appendages, in contrast to separate nanoprecipitate formation. These Janus nanoprecipitates result from local comelting of Bi and Ge during sintering, enabling an amorphous-like lattice thermal conductivity. A precipitate size effect on phonon scattering is observed due to the balance between alloy-disorder and nanoprecipitate scattering. The thermoelectric figure-of-merit ZT reaches 0.6 near room temperature and 1.6 at 773 K. The Janus nanoprecipitation can be introduced into other materials and may act as a general property-tailoring mechanism.

Place, publisher, year, edition, pages
Wiley, 2022
Keywords
atom probe tomography; Janus nanoprecipitation; low thermal conductivity; Mg3Sb2; thermalelectrics
National Category
Other Chemical Engineering
Identifiers
urn:nbn:se:liu:diva-187372 (URN)10.1002/advs.202202594 (DOI)000826658200001 ()35851767 (PubMedID)
Note

Funding Agencies|National Key Research and Development Program of China [2018YFB0703600]; National Natural Science Foundation of China [51872133]; Guangdong Innovative and Entrepreneurial Research Team Program [2016ZT06G587]; Guangdong Provincial Key Laboratory Program from the Department of Science and Technology of Guangdong Province [2021B1212040001]; Tencent Foundation through the XPLORER PRIZE; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO-Mat-LiU) [2009 00971]; Knut and Alice Wallenberg foundation through the Wallenberg Academy Fellows program [KAW-2020.0196]; Swedish Foundation for Strategic Research (SSF) [RIF 14-0074]; German Science Foundation (DFG) [SFB 917]

Available from: 2022-08-19 Created: 2022-08-19 Last updated: 2023-12-28Bibliographically approved
Majed, A., Kothakonda, M., Wang, F., Tseng, H.-H., Prenger, K., Zhang, X., . . . Naguib, M. (2022). Transition Metal Carbo-Chalcogenide "TMCC": A New Family of 2D Materials. Advanced Materials, 34(26), Article ID 2200574.
Open this publication in new window or tab >>Transition Metal Carbo-Chalcogenide "TMCC": A New Family of 2D Materials
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2022 (English)In: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 34, no 26, article id 2200574Article in journal (Refereed) Published
Abstract [en]

A new family of 2D transition metal carbo-chalcogenides (TMCCs) is reported, which can be considered a combination of two well-known families, TM carbides (MXenes) and TM dichalcogenides (TMDCs), at the atomic level. Single sheets are successfully obtained from multilayered Nb2S2C and Ta2S2C using electrochemical lithiation followed by sonication in water. The parent multilayered TMCCs are synthesized using a simple, scalable solid-state synthesis followed by a topochemical reaction. A superconductivity transition is observed at 7.55 K for Nb2S2C. The delaminated Nb2S2C outperforms both multilayered Nb2S2C and delaminated NbS2 as an electrode material for Li-ion batteries. Ab initio calculations predict the elastic constant of TMCC to be over 50% higher than that of TMDC.

Place, publisher, year, edition, pages
Weinheim, Germany: Wiley-VCH Verlagsgesellschaft, 2022
Keywords
2D materials; delamination; superconductors; transition metal carbo-chalcogenides
National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:liu:diva-185435 (URN)10.1002/adma.202200574 (DOI)000797779800001 ()35419882 (PubMedID)2-s2.0-85130283684 (Scopus ID)
Note

Funding Agencies: National Science Foundation [DMR-1752997, DMR-2048164]; Knut and Alice Wallenberg (KAW) Foundation [KAW 2015.0043]; Linköping Electron Microscopy Laboratory; Swedish Foundation for Strategic Research (SSF) [RIF 14-0074, EM16-0004]; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linköping University (Faculty Grant SFO-Mat-LiU) [2009 00971]; U.S. Department of Energy, Office of Science, Basic Energy Science [DE-SC0014208]

Available from: 2022-06-03 Created: 2022-06-03 Last updated: 2023-03-16Bibliographically approved
Bakhit, B., Palisaitis, J., Wu, Z., Sortica, M. A., Primetzhofer, D., Persson, P. O. Å., . . . Greczynski, G. (2021). Age hardening in superhard ZrB2-rich Zr1-xTaxBy thin films. Scripta Materialia, 191, 120-125
Open this publication in new window or tab >>Age hardening in superhard ZrB2-rich Zr1-xTaxBy thin films
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2021 (English)In: Scripta Materialia, ISSN 1359-6462, E-ISSN 1872-8456, Vol. 191, p. 120-125Article in journal (Refereed) 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.

Place, publisher, year, edition, pages
Elsevier, 2021
Keywords
Thin films; Transition-metal (TM) diboridesAge hardening; Thermal stability; Hardness and elastic modulus
National Category
Physical Sciences
Identifiers
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)
Available from: 2020-10-02 Created: 2020-10-02 Last updated: 2024-02-01Bibliographically approved
Thörnberg, J., Palisaitis, J., Hellgren, N., Klimashin, F. F., Ghafoor, N., Zhirkov, I., . . . Rosén, J. (2020). Microstructure and materials properties of understoichiometric TiBx thin films grown by HiPIMS. Surface & Coatings Technology, 404, Article ID 126537.
Open this publication in new window or tab >>Microstructure and materials properties of understoichiometric TiBx thin films grown by HiPIMS
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2020 (English)In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 404, article id 126537Article in journal (Refereed) Published
Abstract [en]

TiBx thin films with a B content of 1.43 ≤ x ≤ 2.70 were synthesized using high-power impulse magnetron sputtering (HiPIMS) and direct-current magnetron sputtering (DCMS). HiPIMS allows compositions ranging from understoichiometric to overstoichiometric dense TiBx thin films with a B/Ti ratio between 1.43 and 2.06, while DCMS yields overstoichiometric TiBx films with a B/Ti ratio ranging from 2.20 to 2.70. Excess B in overstoichiometric TiBx thin films from DCMS results in a hardness up to 37.7 ± 0.8 GPa, attributed to the formation of an amorphous B-rich tissue phase interlacing stoichiometric TiB2 columnar structures. We furthermore show that understoichiometric TiB1.43 thin films synthesized by HiPIMS, where the deficiency of B is found to be accommodated by Ti-rich planar defects, exhibit a superior hardness of 43.9 ± 0.9 GPa. The apparent fracture toughness and thermal conductivity of understoichiometric TiB1.43 HiPIMS films are 4.2 ± 0.1 MPa√m and 2.46 ± 0.22 W/(m·K), respectively, as compared to corresponding values for overstoichiometric TiB2.70 DCMS film samples of 3.1 ± 0.1 MPa√m and 4.52 ± 0.45 W/(m·K). This work increases the fundamental understanding of understoichiometric TiBx thin films and their materials properties, and shows that understoichiometric films have properties matching or going beyond those with excess B.

Place, publisher, year, edition, pages
Elsevier, 2020
Keywords
Borides, Stoichiometry, Titanium, Mechanical properties, Microstructure, HiPIMS
National Category
Other Materials Engineering
Identifiers
urn:nbn:se:liu:diva-172905 (URN)10.1016/j.surfcoat.2020.126537 (DOI)000597889400057 ()2-s2.0-85094613138 (Scopus ID)
Note

Fulltext published under Creative Commons license CC BY 4.0

https://creativecommons.org/licenses/by/4.0/

Funding agencies: Swedish Foundation for Strategic Research (SSF)Swedish Foundation for Strategic Research [EM16-0004]; Research Infrastructure Fellow program from the Knut and Alice Wallenberg (KAW) Foundation [RIF 14-0074]; KAW; Swedish Government Strategic Research Area

Available from: 2021-01-26 Created: 2021-01-26 Last updated: 2021-12-29Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0001-9140-6724

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