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Magnuson, M., Tengdelius, L., Greczynski, G., Eriksson, F., Jensen, J., Lu, J., . . . Högberg, H. (2019). Compositional dependence of epitaxial Tin+1SiCn MAX-phase thin films grown from a Ti3SiC2 compound target. Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, 37(2), Article ID 021506.
Open this publication in new window or tab >>Compositional dependence of epitaxial Tin+1SiCn MAX-phase thin films grown from a Ti3SiC2 compound target
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2019 (English)In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 37, no 2, article id 021506Article in journal (Refereed) Published
Abstract [en]

The authors investigate sputtering of a Ti3SiC2 compound target at temperatures ranging from RT (no applied external heating) to 970 °C as well as the influence of the sputtering power at 850 °C for the deposition of Ti3SiC2 films on Al2O3(0001) substrates. Elemental composition obtained from time-of-flight energy elastic recoil detection analysis shows an excess of carbon in all films, which is explained by differences in the angular distribution between C, Si, and Ti, where C scatters the least during sputtering. The oxygen content is 2.6 at. % in the film deposited at RT and decreases with increasing deposition temperature, showing that higher temperatures favor high purity films. Chemical bonding analysis by x-ray photoelectron spectroscopy shows C–Ti and Si–C bonding in the Ti3SiC2 films and Si–Si bonding in the Ti3SiC2 compound target. X-ray diffraction reveals that the phases Ti3SiC2, Ti4SiC3, and Ti7Si2C5 can be deposited from a Ti3SiC2 compound target at substrate temperatures above 850 °C and with the growth of TiC and the Nowotny phase Ti5Si3Cx at lower temperatures. High-resolution scanning transmission electron microscopy shows epitaxial growth of Ti3SiC2, Ti4SiC3, and Ti7Si2C5 on TiC at 970 °C. Four-point probe resistivity measurements give values in the range ∼120 to ∼450 μΩ cm and with the lowest values obtained for films containing Ti3SiC2, Ti4SiC3, and Ti7Si2C5.

Place, publisher, year, edition, pages
American Institute of Physics (AIP), 2019
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-154004 (URN)10.1116/1.5065468 (DOI)000460437200051 ()
Note

Funding agencies: Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University (Faculty Grant SFO-Mat-LiU) [2009-00971]; Swedish Energy Research [43606-1]; Carl Tryggers Foundation [CTS16:303, CTS14:310, CTS 17:166]; Knut 

Available from: 2019-01-22 Created: 2019-01-22 Last updated: 2019-03-20Bibliographically approved
Landälv, L., Carlström, C.-F., Lu, J., Primetzhofer, D., Jöesaar, M. J., Ahlgren, M., . . . Eklund, P. (2019). Phase composition and transformations in magnetron-sputtered (Al,V)2O3 coatings. Thin Solid Films
Open this publication in new window or tab >>Phase composition and transformations in magnetron-sputtered (Al,V)2O3 coatings
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2019 (English)In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731Article in journal (Refereed) In press
Abstract [en]

Coatings of (Al1-xVx)2O3, with x ranging from 0 to 1, were deposited by pulsed DC reactive sputter deposition on Si(100) at a temperature of 550 °C. XRD showed three different crystal structures depending on V-metal fraction in the coating: α-V2O3 rhombohedral structure for 100 at.% V, a defect spinel structure for the intermediate region, 63–42 at.% V. At lower V-content, 18 and 7 at.%, a gamma-alumina-like solid solution was observed, shifted to larger d-spacing compared to pure γ-Al2O3. The microstructure changes from large columnar faceted grains for α-V2O3 to smaller equiaxed grains when lowering the vanadium content towards pure γ-Al2O3. Annealing in air resulted in formation of V2O5 crystals on the surface of the coating after annealing to 500 °C for 42 at.% V and 700 °C for 18 at.% V metal fraction respectively. The highest thermal stability was shown for pure γ-Al2O3-coating, which transformed to α-Al2O3 after annealing to 1100 °C. Highest hardness was observed for the Al-rich oxides, ~24 GPa. The latter decreased with increasing V-content, larger than 7 at.% V metal fraction. The measured hardness after annealing in air decreased in conjunction with the onset of further oxidation of the coatings.

Place, publisher, year, edition, pages
Elsevier, 2019
Keywords
Aluminum vanadium oxide Pulsed DC magnetron sputtering Annealing V2O5 AlVO4 AlVO3
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-159749 (URN)10.1016/j.tsf.2019.06.019 (DOI)
Available from: 2019-08-20 Created: 2019-08-20 Last updated: 2019-08-20Bibliographically approved
Pilemalm, R., Pourovskii, L., Mosyagin, I., Simak, S. & Eklund, P. (2019). Thermodynamic Stability, Thermoelectric, Elastic and Electronic Structure Properties of ScMN2-Type (M = V, Nb, Ta) Phases Studied by ab initio Calculations. Condensed Matter, 4(2), Article ID 36.
Open this publication in new window or tab >>Thermodynamic Stability, Thermoelectric, Elastic and Electronic Structure Properties of ScMN2-Type (M = V, Nb, Ta) Phases Studied by ab initio Calculations
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2019 (English)In: Condensed Matter, ISSN 2410-3896, Vol. 4, no 2, article id 36Article in journal (Refereed) Published
Abstract [en]

ScMN2-type (M = V, Nb, Ta) phases are layered materials that have been experimentally reported for M = Ta and Nb, but they have up to now not been much studied. However, based on the properties of binary ScN and its alloys, it is reasonable to expect these phases to be of relevance in a range of applications, including thermoelectrics. Here, we have used first-principles calculations to study their thermodynamic stability, elastic, thermoelectric and electronic properties. We have used density functional theory to calculate lattice parameters, the mixing enthalpy of formation and electronic density of states as well as the thermoelectric properties and elastic constants (cij), bulk (B), shear (G) and Young’s (E) modulus, which were compared with available experimental data. Our results indicate that the considered systems are thermodynamically and elastically stable and that all are semiconductors with small band gaps. All three materials display anisotropic thermoelectric properties and indicate the possibility to tune these properties by doping. In particular, ScVN2, featuring the largest band gap exhibits a particularly large and strongly doping-sensitive Seebeck coefficient.

Place, publisher, year, edition, pages
Basel: MDPI, 2019
Keywords
ScTaN2; inverse MAX phase; thermoelectric properties; density functional theory
National Category
Physical Sciences Condensed Matter Physics
Identifiers
urn:nbn:se:liu:diva-156671 (URN)10.3390/condmat4020036 (DOI)000475286700002 ()
Note

Funding agencies: Swedish Research Council (VR) [2016-03365]; Knut and AliceWallenberg Foundation through the Academy Fellows Program; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [2009 00971]; European Res

Available from: 2019-05-07 Created: 2019-05-07 Last updated: 2019-07-30Bibliographically approved
Paul, B., Björk, E. M., Kumar, A., Lu, J. & Eklund, P. (2018). Nanoporous Ca3Co4O9 Thin Films for Transferable Thermoelectrics. ACS applied energy materials, 1(5), 2261-2268
Open this publication in new window or tab >>Nanoporous Ca3Co4O9 Thin Films for Transferable Thermoelectrics
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2018 (English)In: ACS applied energy materials, ISSN 2574-0962, Vol. 1, no 5, p. 2261-2268Article in journal (Refereed) Published
Abstract [en]

The development of high-performance and transferable thin-film thermoelectric materials is important for low-power applications, e.g., to power wearable electronics, and for on-chip cooling. Nanoporous films offer an opportunity to improve thermoelectric performance by selectively scattering phonons without affecting electronic transport. Here, we report the growth of nanoporous Ca3Co4O9 thin films by a sequential sputtering-annealing method. Ca3Co4O9 is promising for its high Seebeck coefficient and good electrical conductivity and important for its nontoxicity, low cost, and abundance of its constituent raw materials. To grow nanoporous films, multilayered CaO/CoO films were deposited on sapphire and mica substrates by rf-magnetron reactive sputtering from elemental Ca and Co targets, followed by annealing at 700 C to form the final phase of Ca3Co4O9. This phase transformation is accompanied by a volume contraction causing formation of nanopores in the film. The thermoelectric propoperties of the nanoporous Ca3Co4O9 films can be altered by controlling the porosity. The lowest electrical resistivity is ~7 mO cm, yielding a power factor of 2.32 × 10-4 Wm-1K-2 near room temperature. Furthermore, the films are transferable from the primary mica substrates to other arbitrary polymer platforms by simple dry transfer, which opens an opportunity of low-temperature use these materials.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2018
Keywords
Ca3Co4O9; nanoporous; thermoelectrics; thin film; transferable
National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:liu:diva-155845 (URN)10.1021/acsaem.8b00333 (DOI)000458705500058 ()29905306 (PubMedID)
Available from: 2019-03-29 Created: 2019-03-29 Last updated: 2019-04-04Bibliographically approved
Halim, J., Palisaitis, J., Lu, J., Thörnberg, J., E. J., M., M., P., . . . Rosén, J. (2018). Synthesis of Two-Dimensional Nb1.33C (MXene) with Randomly Distributed Vacancies by Etching of the Quaternary Solid Solution (Nb2/3Sc1/3)2AlC MAX Phase. ACS Applied Nano Materials, 1(6), 2455-2460
Open this publication in new window or tab >>Synthesis of Two-Dimensional Nb1.33C (MXene) with Randomly Distributed Vacancies by Etching of the Quaternary Solid Solution (Nb2/3Sc1/3)2AlC MAX Phase
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2018 (English)In: ACS Applied Nano Materials, ISSN 2574-0970, Vol. 1, no 6, p. 2455-2460Article in journal (Refereed) Published
Abstract [en]

Introducing point defects in two-dimensional (2D) materials can alter or enhance their properties. Here, we demonstrate how etching a laminated (Nb2/3Sc1/3)2AlC MAX phase (solid solution) of both the Sc and Al atoms results in a 2D Nb1.33C material (MXene) with a large number of vacancies and vacancy clusters. This method is applicable to any quaternary, or higher, MAX phase, wherein one of the transition metals is more reactive than the other and could be of vital importance in applications such as catalysis and energy storage. We also report, for the first time, on the existence of solid solution (Nb2/3Sc1/3)3AlC2 and (Nb2/3Sc1/3)4AlC3 phases.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2018
Keywords
2D material; electronic properties; MXene; synthesis; transition-metal carbide
National Category
Materials Chemistry
Identifiers
urn:nbn:se:liu:diva-151667 (URN)10.1021/acsanm.8b00332 (DOI)
Available from: 2018-09-28 Created: 2018-09-28 Last updated: 2019-06-28Bibliographically approved
Zhou, J., Zha, X., Chen, F. Y., Ye, Q., Eklund, P., Du, S. & Huang, Q. (2016). A Two-Dimensional Zirconium Carbide by Selective Etching of Al3C3 from Nanolaminated Zr3Al3C5. Angewandte Chemie International Edition, 55(16), 5008-5013
Open this publication in new window or tab >>A Two-Dimensional Zirconium Carbide by Selective Etching of Al3C3 from Nanolaminated Zr3Al3C5
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2016 (English)In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 55, no 16, p. 5008-5013Article in journal (Refereed) Published
Abstract [en]

The room-temperature synthesis of a new two-dimensional (2D) zirconium-containing carbide, Zr3C2Tz MXene is presented. In contrast to traditional preparation of MXene, the layered ternary Zr3Al3C5 material instead of MAX phases is used as source under hydrofluoric acid treatment. The structural, mechanical, and electronic properties of the synthesized 2D carbide are investigated, combined with first-principles density functional calculations. A comparative study on the structrual stability of our obtained 2D Zr3C2Tz and Ti3C2Tz MXenes at elevated temperatures is performed. The obtained 2D Zr3C2Tz exhibits relatively better ability to maintain 2D nature and strucural integrity compared to Ti-based Mxene. The difference in structural stability under high temperature condition is explained by a theoretical investigation on binding energy.

Place, publisher, year, edition, pages
Wiley-Blackwell, 2016
Keywords
carbides; layered structures; nanosheets; selective extraction; thermal stability
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-127775 (URN)10.1002/anie.201510432 (DOI)000374496100024 ()26959082 (PubMedID)
Note

Funding Agencies|National Natural Science Foundation of China [91226202, 91426304]; Chinese Academy of Sciences [XDA02040105, XDA03010305]; CAS Interdisciplinary Innovation Team Project; Ministry of Science and Technology of China [2015ZX06004-001]

Available from: 2016-05-12 Created: 2016-05-12 Last updated: 2017-11-30
Kerdsongpanya, S., Eriksson, F., Jensen, J., Lu, J., Sun, B., Kan Koh, Y., . . . Eklund, P. (2016). Experimental and Theoretical Investigation of Cr1-xScxN Solid Solutions for Thermoelectric Applications. Journal of Applied Physics, 120(21), Article ID 215103.
Open this publication in new window or tab >>Experimental and Theoretical Investigation of Cr1-xScxN Solid Solutions for Thermoelectric Applications
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2016 (English)In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 120, no 21, article id 215103Article in journal (Refereed) Published
Abstract [en]

We investigate the trends in mixing thermodynamics of Cr1-xScxN solid solutions in the cubic B1 structure and their electronic density of state by first-principle calculations, and thin-film synthesis of Cr1-xScxN solid solutions by reactive dc magnetron sputtering. Films with the composition Cr0.92Sc0.08N exhibit a thermoelectric power factor of about 8x10-4 Wm-1K-2at 770 K, similar to CrN. The results show that the disordered Cr1-xScxN solid solutions is thermodynamically stable in B1 solid solutions at T = 800°C rather than in the B1- L11 ordered solid solutions stable at 0 K. The calculated electronic density of state (DOS) indicates a positive bowing parameter for the electronic band gap of Cr1-xScxN solid solutions. The calculated DOS suggest possible improvement of power factor due to Sc 3d orbital delocalization on Cr 3d orbital gives decreasing electrical resistivity with retained Seebeck coefficient in Cr-rich regime, consistent with the experimentally observed high power factor for the solid solution.

Place, publisher, year, edition, pages
American Institute of Physics (AIP), 2016
Keywords
Chromium nitride, Scandium nitride, Thermoelectrics, First-principles calculations, Solid solutions
National Category
Physical Sciences
Identifiers
urn:nbn:se:liu:diva-117757 (URN)10.1063/1.4968570 (DOI)000390602600026 ()
Note

Funding agencies: European Research Council under the European Communitys Seventh Framework Programme [335383]; Swedish Research Council (VR) [621-2012-4430, 621-2011-4417, 330-2014-6336]; Marie Sklodowska Curie Actions [INCA 60098]; Linnaeus Strong Research Environment Li

Available from: 2015-05-08 Created: 2015-05-08 Last updated: 2017-12-04Bibliographically approved
Lapauw, T., Lambrinou, K., Cabioch, T., Halim, J., Lu, J., Pesach, A., . . . Vleugels, J. (2016). Synthesis of the new MAX phase Zr2AlC. Journal of the European Ceramic Society, 36(8), 1847-1853
Open this publication in new window or tab >>Synthesis of the new MAX phase Zr2AlC
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2016 (English)In: Journal of the European Ceramic Society, ISSN 0955-2219, E-ISSN 1873-619X, Vol. 36, no 8, p. 1847-1853Article in journal (Refereed) Published
Abstract [en]

This study reports on the first experimental evidence of the existence of the Zr2AlC MAX phase, synthesised by means of reactive hot pressing of a ZrH2, Al and C powder mixture. The crystal structure of this compound was investigated by X-ray and neutron diffraction. The lattice parameters were determined and confirmed by high-resolution transmission electron microscopy. The effect of varying the synthesis temperature was investigated, indicating a relatively narrow temperature window for the synthesis of Zr2AlC. ZrC was always present as a secondary phase by hot pressing in the 1475-1575 degrees C range.

Place, publisher, year, edition, pages
ELSEVIER SCI LTD, 2016
Keywords
MAX phase ceramics; Diffraction analysis; Reactive hot pressing
National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:liu:diva-127738 (URN)10.1016/j.jeurceramsoc.2016.02.044 (DOI)000374082900001 ()
Note

Funding Agencies|Agency for Innovation by Science and Technology (IWT), Flanders, Belgium [131081]; European Atomic Energy Communitys (Euratom) Seventh Framework Programme FP7 [604862]; EERA (European Energy Research Alliance) Joint Programme on Nuclear Materials (JPNM); Hercules Foundation [ZW09-09]; Swedish Foundation for Strategic Research through the Synergy Grant FUNCASE; Swedish Foundation for Strategic Research through the Future Research Leaders 5 program

Available from: 2016-05-12 Created: 2016-05-12 Last updated: 2018-03-21
Cabioch, T., Alkazaz, M., Beaufort, M.-F., Nicolai, J., Eyidi, D. & Eklund, P. (2016). Ti2AlN thin films synthesized by annealing of (Ti plus Al)/AlN multilayers. Materials research bulletin, 80, 58-63
Open this publication in new window or tab >>Ti2AlN thin films synthesized by annealing of (Ti plus Al)/AlN multilayers
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2016 (English)In: Materials research bulletin, ISSN 0025-5408, E-ISSN 1873-4227, Vol. 80, p. 58-63Article in journal (Refereed) Published
Abstract [en]

Single-phase Ti2AlN thin films were obtained by annealing in vacuum of (Ti + Al)/AIN multilayers deposited at room temperature by magnetron sputtering onto single-crystalline (0001) 4H-SiC and (0001) Al2O3 substrates. In-situ X-ray diffraction experiments combined with ex-situ cross-sectional transmission electron microscopy observations reveal that interdiffusion processes occur in the multilayer at a temperature of similar to 400 degrees C leading to the formation of a (Ti, Al, N) solid solution, having the hexagonal structure of alpha-Ti, whereas the formation of Ti2AlN occurs at 550-600 degrees C. Highly oriented (0002) Ti2AlN thin films can be obtained after an annealing at 750 degrees C. (C) 2016 Elsevier Ltd. All rights reserved.

Place, publisher, year, edition, pages
PERGAMON-ELSEVIER SCIENCE LTD, 2016
Keywords
Annealing; MAX phases; Thin films; Multilayer
National Category
Inorganic Chemistry
Identifiers
urn:nbn:se:liu:diva-130056 (URN)10.1016/j.materresbull.2016.03.031 (DOI)000377230900008 ()
Note

Funding Agencies|University of Poitiers; European Research Council under the European Communitys Seventh Framework Programme/ERC [335383]; Swedish Foundation for Strategic Research through the Future Leaders 5 program

Available from: 2016-07-06 Created: 2016-07-06 Last updated: 2017-11-28
Yu, H., Suo, X., Gong, Y., Zhu, Y., Zhou, J., Li, H., . . . Huang, Q. (2016). Ti3AlC2 coatings deposited by liquid plasma spraying. Surface & Coatings Technology, 299, 123-128
Open this publication in new window or tab >>Ti3AlC2 coatings deposited by liquid plasma spraying
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2016 (English)In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 299, p. 123-128Article in journal (Refereed) Published
Abstract [en]

Ti3AlC2 tends to partially decompose into TiC phase during deposition by traditional thermal spray techniques, preventing their use in surface anti-corrosion applications. Here, Ti3AlC2 coatings were synthesized using liquid plasma spraying (LPS). Although the average temperature of particles measured in LPS was higher than 2200 K, enough to decompose Ti3AlC2 phase, the resulting sprayed Ti3AlC2 particles were intact. This is probably due to formation of a protective oxide on the surface in the high-temperature steam. The phase purity of Ti3AlC2 coating was high when using water as solvent, but low with a solvent of a mixture of water and alcohol. Different pH values of the solutions influence the phase purity of Ti3AlC2 coatings. The alkaline solutions show detrimental effect on the conservation of Ti3AlC2 phase. The mechanism of improved structural integrity of Ti3AlC2 phase at high temperature through LPS was revealed by microstructural and compositional analysis. (C) 2016 Elsevier B.V. All rights reserved.

Place, publisher, year, edition, pages
ELSEVIER SCIENCE SA, 2016
Keywords
Liquid plasma spraying; Ti3AlC2; Decomposition
National Category
Manufacturing, Surface and Joining Technology
Identifiers
urn:nbn:se:liu:diva-130257 (URN)10.1016/j.surfcoat.2016.04.076 (DOI)000378664900016 ()
Note

Funding Agencies|National Natural Science Foundation of China [91226202, 91426304]; Chinese Academy of Sciences [XDA 02040105, XDA03010305]; Ministry of Science and Technology of China [2015 ZX06004-001]; Swedish Foundation for Strategic Research (SSF); Synergy Grant FUNCASE

Available from: 2016-08-01 Created: 2016-07-28 Last updated: 2017-11-28
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ORCID iD: ORCID iD iconorcid.org/0000-0003-1785-0864

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