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  • 101.
    Lauridsen, Jonas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Jensen, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Ljungcrantz, H
    Impact Coatings AB.
    Oberg, A
    ABB Corp Research.
    Lewin, E
    Uppsala University.
    Jansson, U
    Uppsala University.
    Flink, A
    Impact Coatings AB.
    Hogberg, H
    Impact Coatings AB.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Microstructure evolution of Ti-Si-C-Ag nanocomposite coatings deposited by DC magnetron sputtering2010In: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 58, no 20, p. 6592-6599Article in journal (Refereed)
    Abstract [en]

    Nanocomposite coatings consisting of Ag and TiCx (x andlt; 1) crystallites in a matrix of amorphous SiC were deposited by high-rate magnetron sputtering from Ti-Si-C-Ag compound targets. Different target compositions were used to achieve coatings with a Si content of similar to 13 at.%, while varying the C/Ti ratio and Ag content. Electron microscopy, helium ion microscopy, X-ray photoelectron spectroscopy and X-ray diffraction were employed to trace Ag segregation during deposition and possible decomposition of amorphous SiC. Eutectic interaction between Ag and Si is observed, and the Ag forms threading grains which coarsen with increased coating thickness. The coatings can be tailored for conductivity horizontally or vertically by controlling the shape and distribution of the Ag precipitates. Coatings were fabricated with hardness in the range 10-18 GPa and resistivity in the range 77-142 mu Omega cm.

  • 102.
    Lauridsen, Jonas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Joelsson, T.
    Impact Coatings AB.
    Ljungcrantz, H.
    Impact Coatings AB.
    Öberg, Å.
    ABB Corporate Research.
    Lewin, E.
    Uppsala University, Sweden.
    Jansson, U.
    Uppsala University, Sweden.
    Beckers, Manfred
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Högberg, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    High-rate deposition of amorphous and nanocomposite Ti-Si-C multifunctional coatings2010In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 205, no 2, p. 299-305Article in journal (Refereed)
    Abstract [en]

    Amorphous (a) and nanocomposite Ti–Si–C coatings were deposited at rates up to 16 μm/h by direct current magnetron sputtering from a Ti3SiC2 compound target, using an industrial pilot-plant system, onto high-speed steel, Si, and SiO2 substrates as well as Ni-plated Cu cylinders, kept at a temperature of 200 or 270 °C. Electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction analyses showed that TiC/a-C/a-SiC nanocomposites were formed consisting of textured TiC nanocrystallites (nc) embedded in a matrix of a-C and a-SiC. Elastic recoil detection analysis showed that coatings deposited at a target-to-substrate distance of 2 cm and an Ar pressure of 10 mTorr have a composition close to that of the Ti3SiC2 compound target, as explained by ballistic transport of the species. Increased target-to-substrate distance from 2 cm to 8 cm resulted in a higher carbon-to-titanium ratio in the coatings than for the Ti3SiC2 compound target, due to different gas-phase scattering properties between the sputtered species. The coating microstructure could be modified from nanocrystalline to predominantly amorphous by changing the pressure and target-to-substrate conditions to 4 mTorr and 2 cm, respectively. A decreased pressure from 10 mTorr to 4 or 2 mTorr at a target-to-substrate distance of 2 cm decreased the deposition rate up to a factor of ~7 as explained by resputtering and an increase in the plasma sheath thickness. The coatings exhibited electrical resistivity in the range 160–800 μΩ cm, contact resistance down to 0.8 mΩ at a contact force of 40 N, and nanoindentation hardness in the range of 6–38 GPa.

  • 103.
    Lauridsen, Jonas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Knutsson, A
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, The Institute of Technology.
    Mannerbro, R
    ABB Components, Sweden.
    Andersson, A M
    ABB Corp Research.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Microstructural and Chemical Analysis of AgI Coatings Used as a Solid Lubricant in Electrical Sliding Contacts2012In: Tribology letters, ISSN 1023-8883, E-ISSN 1573-2711, Vol. 46, no 2, p. 187-193Article in journal (Refereed)
    Abstract [en]

    AgI coatings have been deposited by electroplating on Ag-plated Cu coupons. Electron microscopy shows that the coatings consist of weakly agglomerated AgI grains. X-ray diffraction, differential scanning calorimetry, thermogravimetry, and mass spectrometry show that the AgI exhibits a reversible transformation from hexagonal to cubic phase at 150 A degrees C. AgI starts to decompose at 150 A degrees C with an accelerating rate up to the AgI melting temperature (555 A degrees C), where a complex-bonded hydroxide evaporates. Ag pin-on-disk testing shows that the iodine addition to Ag decreases the friction coefficient from 1.2 to similar to 0.4. The contact resistance between AgI and Ag becomes less than 100 mu I (c) after similar to 500 operations as the AgI deagglomerates, and Ag is exposed on the surface and remains low during at least 10,000 reciprocating operations. This makes AgI suitable as a solid lubricant in electrical contacts.

  • 104.
    Lauridsen, Jonas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Knutsson, Axel
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials . Linköping University, The Institute of Technology.
    Mannerbro, R.
    ABB Components, Lyviksvägen 10, SE-771 41, Ludvika, Sweden.
    Andersson, A. M.
    ABB Corporate Research, Forskargränd 7, SE-721 78, Västerås, Sweden.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    AgI as a solid lubricant in electrical contactsManuscript (preprint) (Other academic)
    Abstract [en]

    AgI coatings have been deposited by electroplating on Ag plated Cu coupons. Electron microscopy shows that the coatings consist of weakly agglomerated AgI grains. X-ray diffraction, differential scanning  calorimetry, thermogravimetry and mass spectrometry show that the AgI exhibits a reversible transformation from hexagonal to cubic phase at 150 °C. AgI starts to decompose at 150 °C with an accelerating rate up to the AgI melting temperature (555 °C), where a complex-bonded  hydroxide evaporates. Ag-pin-on-disk testing shows that the iodine addition to Ag decreases the friction coefficient from 1.2 to ~0.4. The contact resistance between AgI and Ag becomes less than 100 μΩ after ~500 operations as the AgI deagglomerates and Ag is exposed on the surface, and remains low during at least 10000 reciprocating operations. This makes AgI suitable as a solid lubricant in electrical contacts.

  • 105.
    Lauridsen, Jonas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Öberg, Åke
    ABB Corporate Research, Västerås, Sweden.
    Lindgren, Mats
    SP Technical Research Institute of Sweden, Borås, Sweden.
    Fast, Lars
    SP Technical Research Institute of Sweden, Borås, Sweden.
    Lewin, Erik
    Uppsala University, Sweden.
    Jansson, Ulf
    Uppsala University, Sweden.
    Deposition of Ti-Si-C-Ag nanocomposite coatings as electrical contact material2010In: Proceedings of the 56th IEEE Holm Conference on Electrical Contacts (HOLM), IEEE , 2010, p. 288-294Conference paper (Other academic)
    Abstract [en]

    This paper is a brief review of our recent work and a follow up study on nanocomposite coatings comprising nanocrystalline TiC embedded in an amorphous SiC matrix (nc-TiC/a-SiC) with and without Ag additions applied as electrical contacts. These coating materials are deposited at very high deposition rates (>10 μm/h), to meet industrial demands of high productivity. Here we consider Ti-Si-C-Ag nanocomposite coatings with Ag content in the range of 0-22 at.% deposited in a pilot-plant or an industrial deposition system by dc magnetron sputtering from compound targets onto Si(100) and SiO2(100) substrates. The microstructure, electrical, and mechanical properties of the coatings were studied with transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, electrical contact resistance, resistivity, and nanoindentation measurements. Varying the deposition parameters bias and pressure within ranges typical of coating processing had no effect on the structure. A variation was, however, observed for the contact resistance, that was determined to be in the range 400-900 mΩ at a contact force between 1.9-2.65 N. The coatings with highest Ag content had the lowest contactresistance.

  • 106.
    Lauridsen, Jonas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Nedfors, N.
    Department of Materials Chemistry, The Ångström Laboratory, Uppsala University, P.O. Box 538, SE-751 21 Uppsala, Sweden.
    Jansson, U.
    Department of Materials Chemistry, The Ångström Laboratory, Uppsala University, P.O. Box 538, SE-751 21 Uppsala, Sweden.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Ti-B-C nanocomposite coatings deposited by magnetron sputteringManuscript (preprint) (Other academic)
    Abstract [en]

    Ti-B-C nanocomposite coatings with a B content of 7-16 at.%, have been deposited by magnetron sputtering from B4C, Ti, and C targets. X-ray diffraction, photoelectron spectroscopy, and electron microscopy show that the coatings consist of nanocrystalline (nc) TiC:B embedded in a matrix of amorphous (a) BCx and C. The fraction of amorphous phase scales with the Ti concentration, where the matrix predominantly consists of free C with some BCx in coatings with 8 at.% B, while the matrix  predominantly consists of BCx with some free C in coatings with 16 at.% B. Nc-TiC:B/a-BCx/a-C coatings with low amount of free C exhibit a contact resistance comparable to the contact resistance of an Ag sputtered coating at loads of ~1 N against an Au probe.

  • 107.
    Lauridsen, Jonas
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Nedfors, N
    Uppsala University, Sweden .
    Jansson, U
    Uppsala University, Sweden .
    Jensen, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Ti-B-C nanocomposite coatings deposited by magnetron sputtering2012In: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 258, no 24, p. 9907-9912Article in journal (Refereed)
    Abstract [en]

    Ti-B-C nanocomposite coatings with a B content of 8-17 at.% have been deposited by magnetron sputtering from B4C, Ti, and C targets. X-ray diffraction, photoelectron spectroscopy, and electron microscopy show that the coatings consist of nanocrystalline (nc) TiC: B embedded in a matrix of amorphous (a) C, BCx, TiOx and BOx. The fraction of amorphous phase scales with the Ti concentration, where the matrix predominantly consists of free C with some BCx in coatings with a C/Ti ratio andgt; 1, while the matrix predominantly consists of BCx with some free C in coatings with a C/Ti ratio andlt; 1. nc-TiC:B/a-BCx/a-C coatings with low amount of free C exhibit a contact resistance comparable to the contact resistance of an Ag sputtered coating at loads of similar to 1 N against an Au probe, despite the O content of similar to 16 at.%.

  • 108.
    Le Febvrier, Arnaud
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Jensen, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Wet-cleaning of MgO(001): Modification of surface chemistry and effects on thin film growth investigated by x-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectroscopy2017In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 35, no 2, article id 021407Article in journal (Refereed)
    Abstract [en]

    The effect of the wet-cleaning process using solvents and detergent on the surface chemistry of MgO(001) substrate for film deposition was investigated. Six different wet-cleaning processes using solvent and detergent were compared. The effect on film growth was studied by the example system ScN. The surface chemistry of the cleaned surface was studied by x-ray photoelectron spectroscopy and the film/substrate interface after film growth was investigated by time-of-flight secondary ion mass spectroscopy. The surface composition is dependent on the wet-cleaning process. Sonication in a detergent before the solvents yield a pure oxide surface compared to hydroxide/carbonate contaminated surface for all the other processes. An annealing step is efficient for the removal of carbon contamination as well as most of the hydroxide or carbonates. The study of the film/substrate interface revealed that the wet-cleaning process significantly affects the final interface and film quality. The substrate cleaned with detergent followed by solvent cleaning exhibited the cleanest surface of the substrate before annealing, after annealing, in addition to the sharpest film/substrate interface. (C) 2017 American Vacuum Society.

  • 109.
    Le Febvrier, Arnaud
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Tureson, Nina
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Stilkerich, Nina
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Greczynski, Grzegorz
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Effect of impurities on morphology, growth mode, and thermoelectric properties of (111) and (001) epitaxial-like ScN films2019In: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 52, no 3, article id 035302Article in journal (Refereed)
    Abstract [en]

    ScN is an emerging semiconductor with an indirect bandgap. It has attracted attention for its thermoelectric properties, use as seed layers, and for alloys for piezoelectric application. ScN and other transition metal nitride semiconductors used for their interesting electrical properties are sensitive to contaminants, such as oxygen or fluorine. In this present article, the influence of depositions conditions on the amount of oxygen contaminants incorporated in ScN films were investigated and their effects on the electrical properties (electrical resistivity and Seebeck coefficient) were studied. Epitaxial-like films of thickness 125 +/- 5 nm to 155 +/- 5 nm were deposited by DC-magnetron sputtering on c-plane Al-2, O-3(111) and r-plane Al2O3 at substrate temperatures ranging from 700 degrees C to 950 degrees C. The amount of oxygen contaminants in the film, dissolved into ScN or as an oxide, was related to the adatom mobility during growth, which is affected by the deposition temperature and the presence of twin domain growth. The lowest values of electrical resistivity of 50 mu Omega cm were obtained on ScN(1 1 1)/ MgO(111) and on ScN(001)/r-plane Al2O3 grown at 950 degrees C with no twin domains and the lowest amount of oxygen contaminant. At the best, the films exhibited an electrical resistivity of 50 mu Omega cm with Seebeck coefficient values maintained at -40 mu V K-1, thus a power factor estimated at 3.2 x 10(-3) W m(-1) K-2 (at room temperature).

  • 110.
    Le Febvrier, Arnaud
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Van Nong, Ngo
    Tech Univ Denmark, Denmark.
    Abadias, Gregory
    Univ Poitiers, France.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    P-type Al-doped Cr-deficient CrN thin films for thermoelectrics2018In: APPLIED PHYSICS EXPRESS, ISSN 1882-0778, Vol. 11, no 5, article id 051003Article in journal (Refereed)
    Abstract [en]

    Thermoelectric properties of chromium nitride (CrN)-based films grown on c-plane sapphire by dc reactive magnetron sputtering were investigated. In this work, aluminum doping was introduced in CrN (degenerate n-type semiconductor) by co-deposition. Under the present deposition conditions, over-stoichiometry in nitrogen (CrN1+delta) rock-salt structure is obtained. A p-type conduction is observed with nitrogen-rich CrN combined with aluminum doping. The Cr0.96Al0.04N1.17 film exhibited a high Seebeck coefficient and a sufficient power factor at 300 degrees C. These results are a starting point for designing p-type/n-type thermoelectric materials based on chromium nitride films, which are cheap and routinely grown on the industrial scale. (C) 2018 The Japan Society of Applied Physics

  • 111.
    Li, Mian
    et al.
    Chinese Acad Sci, Peoples R China.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Luo, Kan
    Chinese Acad Sci, Peoples R China.
    Li, Youbing
    Chinese Acad Sci, Peoples R China.
    Chang, Keke
    Chinese Acad Sci, Peoples R China.
    Chen, Ke
    Chinese Acad Sci, Peoples R China.
    Zhou, Jie
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Rosén, Johanna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Persson, Per O A
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Du, Shiyu
    Chinese Acad Sci, Peoples R China.
    Chai, Zhifang
    Chinese Acad Sci, Peoples R China.
    Huang, Zhengren
    Chinese Acad Sci, Peoples R China.
    Huang, Qing
    Chinese Acad Sci, Peoples R China.
    Element Replacement Approach by Reaction with Lewis Acidic Molten Salts to Synthesize Nanolaminated MAX Phases and MXenes2019In: Journal of the American Chemical Society, ISSN 0002-7863, E-ISSN 1520-5126, Vol. 141, no 11, p. 4730-4737Article in journal (Refereed)
    Abstract [en]

    Nanolaminated materials are important because of their exceptional properties and wide range of applications. Here, we demonstrate a general approach to synthesizing a series of Zn-based MAX phases and Cl-terminated MXenes originating from the replacement reaction between the MAX phase and the late transition-metal halides. The approach is a top-down route that enables the late transitional element atom (Zn in the present case) to occupy the A site in the pre-existing MAX phase structure. Using this replacement reaction between the Zn element from molten ZnCl2 and the Al element in MAX phase precursors (Ti3AlC2, Ti2AlC, Ti2AlN, and V2AlC), novel MAX phases Ti3ZnC2, Ti2ZnC, Ti2ZnN, and V2ZnC were synthesized. When employing excess ZnCl2, Cl-terminated MXenes (such as Ti3C2Cl2 and Ti2CCl2) were derived by a subsequent exfoliation of Ti3ZnC2 and Ti2ZnC due to the strong Lewis acidity of molten ZnCl2. These results indicate that A-site element replacement in traditional MAX phases by late transition-metal halides opens the door to explore MAX phases that are not thermodynamically stable at high temperature and would be difficult to synthesize through the commonly employed powder metallurgy approach. In addition, this is the first time that exclusively Cl-terminated MXenes were obtained, and the etching effect of Lewis acid in molten salts provides a green and viable route to preparing MXenes through an HF-free chemical approach.

    The full text will be freely available from 2020-03-01 16:05
  • 112.
    Li, Youbing
    et al.
    Chinese Acad Sci, Peoples R China; Univ Chinese Acad Sci, Peoples R China.
    Li, Mian
    Chinese Acad Sci, Peoples R China.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Ma, Baokai
    Chinese Acad Sci, Peoples R China; Ningbo Univ, Peoples R China.
    Wang, Zhipan
    Ningbo Univ, Peoples R China.
    Cheong, Ling-Zhi
    Ningbo Univ, Peoples R China.
    Luo, Kan
    Chinese Acad Sci, Peoples R China.
    Zha, Xianhu
    Chinese Acad Sci, Peoples R China.
    Chen, Ke
    Chinese Acad Sci, Peoples R China.
    Persson, Per O A
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Shen, Cai
    Chinese Acad Sci, Peoples R China.
    Wang, Qigang
    Tongji Univ, Peoples R China.
    Xue, Jianming
    Peking Univ, Peoples R China.
    Du, Shiyu
    Chinese Acad Sci, Peoples R China.
    Huang, Zhengren
    Chinese Acad Sci, Peoples R China.
    Chai, Zhifang
    Chinese Acad Sci, Peoples R China.
    Huang, Qing
    Chinese Acad Sci, Peoples R China.
    Single-Atom-Thick Active Layers Realized in Nanolaminated Ti-3(AlxCu1-x)C-2 and Its Artificial Enzyme Behavior2019In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 13, no 8, p. 9198-9205Article in journal (Refereed)
    Abstract [en]

    A Ti-3(AlxCu1-x)C-2 phase with Cu atoms with a degree of ordering in the A plane is synthesized through the A site replacement reaction in CuCl2 molten salt. The weakly bonded single -atom -thick Cu layers in a Ti-3(AlxCu1-x)C-2 MAX phase provide actives sites for catalysis chemistry. As -synthesized Ti-3(AlxCu1-x)C-2 presents unusual peroxidase-like catalytic activity similar to that of natural enzymes. A fabricated Ti-3(AlxCu1-x)C-2/chitosan/glassy carbon electrode biosensor prototype also exhibits a low detection limit in the electrochemical sensing of H2O2. These results have broad implications for property tailoring in a nanolaminated MAX phase by replacing the A site with late transition elements.

  • 113.
    Liang, Jiamin
    et al.
    Tianjin Univ, Peoples R China; Chinese Acad Sci, Peoples R China.
    Wei, Qiang
    Tianjin Univ, Peoples R China; Hebei Univ Technol, Peoples R China.
    Ge, Fangfang
    Chinese Acad Sci, Peoples R China.
    Ren, Donglou
    Chinese Acad Sci, Peoples R China.
    Wang, Ji
    Chinese Acad Sci, Peoples R China.
    Dong, Yue
    Chinese Acad Sci, Peoples R China.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Huang, Feng
    Chinese Acad Sci, Peoples R China.
    Du, Shiyu
    Chinese Acad Sci, Peoples R China.
    Huang, Qing
    Chinese Acad Sci, Peoples R China.
    Synthesis of Zr2Al3C4 coatings on zirconium-alloy substrates with Al-C/Si interlayers as diffusion barriers2019In: Vacuum, ISSN 0042-207X, E-ISSN 1879-2715, Vol. 160, p. 128-132Article in journal (Refereed)
    Abstract [en]

    Zr2Al3C4 coatings are potential candidates to prevent claddings of traditional Zr-based alloys from severe oxidation in water steam at high temperature. However, the diffusion of aluminum between coating and substrates at high temperature results in a coating composition deviating from the compositional domain for formation of the Zr2Al3C4 phase. Thus, synthesis of Zr2Al3C4 coatings on zirconium-alloy substrates is challenging. Here, we report that the Zr2Al3C4 phase can be obtained on zirconium alloy (ZIRLO) substrates where an Al-C/Si interlayer deposited by magnetron sputtering is introduced. The Al-C/Si interlayer prevented elemental diffusion of aluminum between the Zr-Al-C coating and the substrates during a post-annealing process at 800 degrees C for 3 h. The Al/Zr ratio of the Zr-Al-C coating after annealing was 0.96 and 0.59 in the cases of with and without Al-C/Si interlayer, respectively. Hence, the Al-C/Si interlayer acts as diffusion barrier and greatly decreases the deviation from the standard stoichiometric ratio of the Zr2Al3C4 phase, which facilitates the formation of the Zr2Al3C4 phase in the final coating.

    The full text will be freely available from 2020-11-16 15:47
  • 114.
    Lunca Popa, Petru
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Sønderby, Steffen
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
    Kerdsongpanya, S.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Bonanos, N.
    Technical University of Denmark, Denmark.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Highly oriented δ-Bi2O3 thin films stable at room temperature synthesized by reactive magnetron sputtering2013In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 113, no 4Article in journal (Refereed)
    Abstract [en]

    We report the synthesis by reactive magnetron sputtering and structural characterization of highly (111)-oriented thin films of δ–Bi2O3. This phase is obtained at a substrate temperature of 150–200 °C in a narrow window of O2/Ar ratio in the sputtering gas (18%–20%). Transmission electron microscopy and x-ray diffraction reveal a polycrystalline columnar structure with (111) texture. The films are stable from room temperature up to 250 °C in vacuum and 350 °C in ambient air.

  • 115.
    Lunca Popa, Petru
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. LIST, Luxembourg.
    Sønderby, Steffen
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering. Tribol Centre, Denmark; National Oilwell Varco Denmark IS, Denmark.
    Kerdsongpanya, Sit
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. Rensselaer Polytech Institute, NY 12180 USA.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Arwin, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Applied Optics . Linköping University, Faculty of Science & Engineering.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Structural, morphological, and optical properties of Bi2O3 thin films grown by reactive sputtering2017In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 624, p. 41-48Article in journal (Refereed)
    Abstract [en]

    Bi2O3 thin films were grown using reactive RF sputtering from a metallic Bi target. The influence of various deposition parameters (substrate temperature, applied power on target and oxygen content in the working gas) on the morphology, structure and optical properties of films was investigated. Depending on the O-2/(Ar + O-2) ratio of the working gas, bismuth, delta-Bi2O3, alpha-Bi2O3 or a mixture of these phases can be deposited, with a narrow window for growth of [111]-oriented delta-Bi2O3 thin films. The delta-Bi2O3 phase is stable from room temperature up to 350 degrees C (in air), where an irreversible transition to alpha-Bi2O3 occurs. This phase transformation is also shown to occur during TEM sample preparation, because of the inherent heating from the ion-milling process, unless liquid -nitrogen cooling is used. (C) 2017 Published by Elsevier B.V.

  • 116.
    Magnuson, Martin
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Mattesini, Maurizio
    Departamento de F í sica de la Tierra, Astronom í a y Astrof í sica I, Universidad Complutense de Madrid, Madrid, Spain; Instituto de Geociencias (CSIC-UCM), Facultad de CC. F í sicas, Madrid, Spain.
    Bugnet, Mattieu
    Département de Physique et Mecanique des Matériaux, Institut Pprime, UPR 3346 CNRS: Université de Poitiers: ENSMA, SP2MI, Futuroscope, France; Department of Materials Science and Engineering, McMaster University, Hamilton, Ontario, Canada.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. Département de Physique et Mecanique des Matériaux, Institut Pprime, UPR 3346 CNRS: Université de Poitiers: ENSMA, SP2MI, Futuroscope, France.
    The origin of anisotropy and high density of states in the electronic structure of Cr2GeC by means of polarized soft X-ray spectroscopy and ab initio calculations2015In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 27, no 41, p. 415501-415509Article in journal (Refereed)
    Abstract [en]

    The anisotropy in the electronic structure of the inherently nanolaminated ternary phase Cr2GeC is investigated by bulk-sensitive and element selective soft x-ray absorption/emission spectroscopy. The angle-resolved absorption/emission measurements reveal di erences between the in-plane and out-of-plane bonding at the (0001) interfaces of Cr2GeC. The Cr L2;3, C K, and Ge M1, M2;3 emission spectra are interpreted with rst-principles density-functional theory (DFT) including core-tovalence dipole transition matrix elements. For the Ge 4s states, the x-ray emission measurements reveal two orders of magnitude higher intensity at the Fermi level than DFT within the General Gradient Approximation (GGA) predicts. We provide direct evidence of anisotropy in the electronic structure and the orbital occupation that should a ect the thermal expansion coecient and transport properties. As shown in this work, hybridization and redistribution of intensity from the shallow 3d core levels to the 4s valence band explain the large Ge density of states at the Fermi level.

  • 117.
    Magnuson, Martin
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Mattesini, Maurizio
    Universidad Complutense de Madrid.
    Van Nong, Ngo
    Technical University of Denmark.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Electronic-structure origin of the anisotropic thermopower of nanolaminated Ti3SiC2 determinedby polarized x-ray spectroscopy and Seebeck measurements2012In: Physical Review B Condensed Matter, ISSN 0163-1829, E-ISSN 1095-3795, Vol. 85, p. 195134-Article in journal (Refereed)
    Abstract [en]

    Nanolaminated materials exhibit characteristic magnetic, mechanical, and thermoelectric properties, withlarge contemporary scientific and technological interest. Here we report on the anisotropic Seebeck coefficient innanolaminated Ti3SiC2 single-crystal thin films and trace the origin to anisotropies in element-specific electronicstates. In bulk polycrystalline form, Ti3SiC2 has a virtually zero Seebeck coefficient over a wide temperaturerange. In contrast, we find that the in-plane (basal ab) Seebeck coefficient of Ti3SiC2, measured on single-crystalfilms, has a substantial and positive value of 4–6 μV/K. Employing a combination of polarized angle-dependentx-ray spectroscopy and density functional theory we directly show electronic structure anisotropy in inherentlynanolaminated Ti3SiC2 single-crystal thin films as a model system. The density of Ti 3d and C 2p states atthe Fermi level in the basal ab plane is about 40% higher than along the c axis. The Seebeck coefficient isrelated to electron and hole-like bands close to the Fermi level, but in contrast to ground state density functionaltheory modeling, the electronic structure is also influenced by phonons that need to be taken into account.Positive contribution to the Seebeck coefficient of the element-specific electronic occupations in the basal planeis compensated by 73% enhanced Si 3d electronic states across the laminate plane that give rise to a negativeSeebeck coefficient in that direction. Strong phonon vibration modes with three to four times higher frequencyalong the c axis than along the basal ab plane also influence the electronic population and themeasured spectra bythe asymmetric average displacements of the Si atoms. These results constitute experimental evidence explainingwhy the average Seebeck coefficient of Ti3SiC2 in polycrystals is negligible over a wide temperature range. Thisallows the origin of anisotropy in physical properties of nanolaminated materials to be traced to anisotropies inelement-specific electronic states.

  • 118.
    Magnuson, Martin
    et al.
    Uppsala University.
    Palmquist, Jens-Petter
    Uppsala University.
    Mattesini, M.
    Uppsala University.
    Li, Sa
    Uppsala University.
    Ahuja, Rajeev
    Uppsala University.
    Eriksson, Olle
    Uppsala University.
    Emmerlich, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Wilhelmsson, Ola
    Uppsala University.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Högberg, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Jansson, Ulf
    Uppsala University.
    Electronic structure investigation of Ti3AlC2 , Ti3SiC2 , and Ti3GeC2 by soft x-ray emission spectroscopy2005In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 72, no 24Article in journal (Refereed)
    Abstract [en]

    The electronic structures of epitaxially grown films of Ti3AlC2 , Ti3SiC2 , and Ti3GeC2 have been investigated by bulk-sensitive soft x-ray emission spectroscopy. The measured high-resolution Ti L , C K , Al L , Si L , and Ge M emission spectra are compared with ab initio density-functional theory including core-to-valence dipole matrix elements. A qualitative agreement between experiment and theory is obtained. A weak covalent Ti-Al bond is manifested by a pronounced shoulder in the Ti L emission of Ti3AlC2 . As Al is replaced with Si or Ge, the shoulder disappears. For the buried Al and Si layers, strongly hybridized spectral shapes are detected in Ti3AlC2 and Ti3SiC2 , respectively. As a result of relaxation of the crystal structure and the increased charge-transfer from Ti to C, the Ti-C bonding is strengthened. The differences between the electronic structures are discussed in relation to the bonding in the nanolaminates and the corresponding change of materials properties.

  • 119.
    Magnuson, Martin
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Tengdelius, Lina
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Greczynski, Grzegorz
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Eriksson, Fredrik
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Jensen, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Samuelsson, Mattias
    Linköping University, Department of Physics, Chemistry and Biology, Nanoscale engineering. Linköping University, Faculty of Science & Engineering.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Högberg, Hans
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Compositional dependence of epitaxial Tin+1SiCn MAX-phase thin films grown from a Ti3SiC2 compound target2019In: 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)
    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.

  • 120.
    Mauchamp, Vincent
    et al.
    University of Poitiers, France.
    Yu, Wenbo
    University of Poitiers, France.
    Gence, Loik
    Catholic University of Louvain, Belgium.
    Piraux, Luc
    Catholic University of Louvain, Belgium.
    Cabioch, Thierry
    University of Poitiers, France.
    Gauthier, Veronique
    University of Poitiers, France.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Dubois, Sylvain
    University of Poitiers, France.
    Anisotropy of the resistivity and charge-carrier sign in nanolaminated Ti2AlC: Experiment and ab initio calculations2013In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 87, no 23Article in journal (Refereed)
    Abstract [en]

    The anisotropy of Ti2AlC transport properties is investigated focusing on the Hall effect and resistivity vs temperature measurements performed on a highly (000l)-oriented thin film and a bulk polycrystalline sample. Experimental data are interpreted on the basis of density functional theory calculations including transport coefficients obtained with the Boltzmann semiclassical transport equation in the isotropic relaxation time approximation. It is shown that the Hall constant is independent of the temperature and that the charge-carrier sign depends on the investigated crystallographic orientation. Charge carriers exhibit a holelike character along the basal plane of the Ti2AlC, whereas the bulk sample Hall constant is negative. The resistivity anisotropy is also evidenced: using an effective medium approach, the room temperature basal plane resistivity is shown to be more than one order of magnitude lower than that along the c axis. This very important anisotropy is shown to result from the anisotropy of the Fermi surface increased by electron-phonon interactions. These interactions are much more important along the c axis than within the basal plane, a situation opposite to that observed in literature for Ti2GeC where resistivity was reported to be isotropic.

  • 121.
    Mian, Li
    et al.
    Chinese Acad Sci, Peoples R China.
    You-Bing, Li
    Chinese Acad Sci, Peoples R China.
    Kan, Luo
    Chinese Acad Sci, Peoples R China.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Persson, Per O A
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Rosén, Johanna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Shi-Yu, Du
    Chinese Acad Sci, Peoples R China.
    Zheng-Ren, Huang
    Chinese Acad Sci, Peoples R China.
    Qing, Huang
    Chinese Acad Sci, Peoples R China.
    Synthesis of Novel MAX Phase Ti3ZnC2 via A-site-element-substitution Approach2019In: Journal of Inorganic Materials, ISSN 1000-324X, Vol. 34, no 1, p. 60-64Article in journal (Refereed)
    Abstract [en]

    Using Ti3AlC2 as the precursor, a new MAX phase Ti3ZnC2 was synthesized via an A-elemental substitution reaction in a molten salts bath. Composition and crystal structure of Ti3ZnC2 were confirmed by XRD, SEM and TEM analysis. Its structure stability and lattice parameter of Ti3ZnC2 were further proved by a theoretical calculation based on density function theory (DFT). Moreover, thermodynamics of A-elemental substitution reactions based on Fe, Co, Ni, and Cu were investigated. All results indicated that the similar substitution reactions are feasible to form series of MAX phases whose A sites are Fe, Co, Ni, and Cu elements. The substitution reaction was achieved by diffusion of Zn atoms into A-layers of Ti3AlC2, which requires Al-Zn eutectic formation at high temperatures. The molten salts provided a moderate environment for substitution reaction and accelerated reaction dynamics. The major advantage of this substitution reaction is that MAX phase keeps individual metal carbide layers intact, thus the formation of competitive phases, such as MA alloys, was avoided. The proposed A-elemental substitution reactions approach opens a new door to design and synthesize novel MAX phases which could not be synthesized by the traditional methods.

  • 122.
    Nedfors, N.
    et al.
    Uppsala University, Sweden .
    Tengstrand, Olof
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Flink, Axel
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology. Impact Coatings AB, Linköping, Sweden.
    Andersson, A. M.
    ABB AB Corporate Research, Västerås, Sweden.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Jansson, U.
    Uppsala University, Sweden .
    Reactive sputtering of NbCx-based nanocomposite coatings: An up-scaling study2014In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 253, p. 100-108Article in journal (Refereed)
    Abstract [en]

    Nanocomposite Nb-C coatings, with a C/Nb ratio of 0.93-1.59, have been deposited by reactive sputtering in a commercial sputtering system where the C is supplied from an acetylene gas at deposition rates of up to 200 nm/min. The coatings are compared to non-reactively sputtered Nb-C coatings deposited from Nb and C targets in lab-scale equipment at deposition rates two orders of magnitude lower. X-ray diffraction, X-ray photoelectron spectroscopy, and electron microscopy are used to conclude that all coatings consist of nanoctystalline Nbc(x) grains (nc-NbCx) embedded in a matrix of amorphous C (a-C). The coating performance was evaluated in terms of their mechanical, tribological, and electrical properties. The chemical stability of the coatings was evaluated by exposure to a flowing mixture of corrosive gases. It is found that the coatings have comparable microstructure and performance to the coatings deposited by non-reactive sputtering. The high deposition rate and presence of different C-radicals on the coating surface during film growth for the reactively sputtered coatings are believed to result in a smaller NbCx grain size compared to the non-reactively sputtered coatings (reactive process: 10-3 nm, non-reactive process: similar to 75-3 nm). This difference results in a thinner a-C matrix of about 0.2 nm, which is not varying with C content for the reactively sputtered coatings. The thinner a-C matrix is reflected in coating properties, with a higher conductivity and slightly higher hardness. The coating richest in C content (C/Nb ratio 1.59) shows the lowest friction (0.23), wear rate (0.17 x 10(-6) mm(3)/mN), and contact resistance before (11 m Omega at 10 N) and after (30 m Omega at 10 N) the chemical stability test. These results imply that nc-NbCx/a-C coatings of this composition are a good candidate for electrical contact applications, and that up-scaling of the process is achievable.

  • 123.
    Nedfors, Nils
    et al.
    Uppsala University, Sweden .
    Tengstrand, Olof
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Jansson, Ulf
    Uppsala University, Sweden .
    Nb-B-C thin films for electrical contact applications deposited by magnetron sputtering2014In: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 32, no 4, p. 041503-Article in journal (Refereed)
    Abstract [en]

    The high wear resistance, high chemical inertness, and high electrical conductivity of magnetron-sputtered transition metal diborides make them a candidate material for sliding electrical contacts. However, their high hardness makes it difficult to penetrate surface oxides, resulting in a high electrical contact resistance. In this study, the authors have investigated how the contact resistance can be improved by the formation of softer Nb-B-C films. The Nb-B-C films were deposited by magnetron sputtering and shown to exhibit a nanocomposite microstructure consisting of nanocrystalline NbB2-x grains with a solid solution of C separated by an amorphous BCx phase. The formation of the BCx phase reduces the hardness from 41 GPa for the NbB2-x film to 19 GPa at 36 at. % C. As a consequence the contact resistance is drastically reduced and the lowest contact resistance of 35 m Omega (contact force 5N) is achieved for a film containing 30 at. % C. However, crack formation and subsequent delamination and fragmentation is observed for the C-containing Nb-B-C films in tribology tests resulting in high friction values for these films.

  • 124.
    Nedfors, Nils
    et al.
    Uppsala University, Sweden.
    Tengstrand, Olof
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Flink, Axel
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Jansson, Ulf
    Uppsala University, Sweden.
    Characterization of amorphous and nanocomposite Nb–Si–C thin films deposited by DC magnetron sputtering2013In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 545, p. 272-278Article in journal (Refereed)
    Abstract [en]

    Two series of Nb–Si–C thin films of different composition have been deposited using DC magnetron sputtering. In the first series the carbon content was kept at about 55 at.% while the Si/Nb ratio was varied and in the second series the C/Nb ratio was varied instead while the Si content was kept at about 45 at.%. The microstructure is strongly dependent on Si content and Nb–Si–C films containing more than 25 at.% Si exhibit an amorphous structure as determined by X-ray diffraction. Transmission electron microscopy, however, induces crystallisation during analysis, thus obstructing a more detailed analysis of the amorphous structure. X-ray photo-electron spectroscopy suggests that the amorphous films consist of a mixture of chemical bonds such as Nb–Si, Nb–C, and Si–C. The addition of Si results in a hardness decrease from 22 GPa for the binary Nb–C film to 18 – 19 GPa for the Si-containing films, while film resistivity increases from 211 μΩcm to 3215 μΩcm. Comparison with recently published results on DC magnetron sputtered Zr–Si–C films, deposited in the same system using the same Ar-plasma pressure, bias, and a slightly lower substrate temperature (300 °C instead of 350 °C), shows that hardness is primarily dependent on the amount of Si–C bonds rather than type of transition metal. The reduced elastic modulus on the other hand shows a dependency on the type of transition metal for the films. These trends for the mechanical properties suggest that high wear resistant (high H/E and H3/E2 ratio) Me–Si–C films can be achieved by appropriate choice of film composition and transition metal.

  • 125.
    Nedfors, Nils
    et al.
    Uppsala University.
    Tengstrand, Olof
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Lewin, Erik
    Uppsala University.
    Furlan, Andrej
    Uppsala University.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Jansson, Ulf
    Uppsala University.
    Structural, mechanical and electrical-contact properties of nanocrystalline-NbC/amorphous-C coatings deposited by magnetron sputtering2011In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 206, no 2-3, p. 354-359Article in journal (Refereed)
    Abstract [en]

    Niobium-carbide nanocomposite coatings with a carbon content varying from 43 to 64 at.% were deposited by dual DC magnetron sputtering. X-ray diffraction, x-ray photoelectron spectroscopy and electron microscopy showed that all coatings consisted of nanometer sized NbC grains embedded in a matrix of amorphous carbon. Mechanical properties and electrical resistivity showed a strong dependency on the amount of amorphous carbon (a-C) and NbC grain size in the coating. The highest hardness (23 GPa), elastic modulus (295 GPa) and the lowest resistivity (260 mu Omega cm) were measured for the coating with about 15% of a-C phase. Contact resistance measurements using a crossed cylinder set-up showed lowest contact resistance for the coating containing 33% a-C (140 mu Omega at a contact force of 100 N), which is comparable to a Ag reference (45 mu Omega at a contact force of 100 N). Comparison with TiC-based nanocomposites studied under similar conditions showed that the Nb-C system has less tendency to form a-C and that lowest contact resistance is obtained at comparable amounts of a-C phase in both material systems (33% for Nb-C compared to 35% for Ti-C). With these good electrical contact properties, the Nb- C nanocomposites can be considered as a potential material for electrical contact applications.

  • 126.
    Nedfors, Nils
    et al.
    Uppsala University, Sweden.
    Tengstrand, Olof
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Persson, Per O A
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Jansson, Ulf
    Uppsala University, Sweden.
    Superhard NbB2 −x thin films deposited by dc magnetron sputtering2014In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 257, p. 295-300Article in journal (Refereed)
    Abstract [en]

    We have deposited weakly textured substoichiometric NbB2-x thin films by magnetron sputtering from an NbB2 target. The films exhibit superhardness (42 +/- 4 GPa), previously only observed in overstoichiometric TiB2 thin films, and explained by a self-organized nanostructuring, where thin TiB2 columnar grains hinder nucleation and slip of dislocations and a B-rich tissue phase between the grains prevent grain-boundary sliding. The wide homogeneity range for the NbB2 phase allows a similar ultra-thin B-rich tissue phase to form between thin (5-10 nm) columnar NbB2-x grains also for films with a B/Nb atomic ratio of 1.8, as revealed here by analytical aberration-corrected scanning transmission electron microscopy. Furthermore, a coefficient of friction of 0.16 is measured for an NbB2-x film sliding against stainless steel with a wear rate of 5 x 10(-7) mm(3)/Nm. X-ray photoelectron spectroscopy results suggest that the low friction is due to the formation of a lubricating boric acid film.

  • 127.
    Nygren, Kristian
    et al.
    Uppsala University, Sweden; Impact Coatings AB, Westmansgatan 29, S-58216 Linkoping, Sweden.
    Mikaela Andersson, Anna
    ABB Corp Research, Sweden.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Jansson, Ulf
    Uppsala University, Sweden.
    Passive films on nanocomposite carbide coatings for electrical contact applications2017In: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 52, no 13, p. 8231-8246Article in journal (Refereed)
    Abstract [en]

    Nanocomposite transition metal carbide/amorphous carbon coatings (Me-C/a-C) deposited by magnetron sputtering have excellent electrical contact properties. The contact resistance can be as low as that of noble metal coatings, although it is known to vary by several orders of magnitude depending on the deposition conditions. We have investigated a nanocrystalline niobium carbide/amorphous carbon (NbC (x) /a-C:H) model system aiming to clarify factors affecting the contact resistance for this group of contact materials. For the first time, the surface chemistry is systematically studied, by angle-resolved X-ray photoelectron spectroscopy, and in extension how it can explain the contact resistance. The coatings presented a mean oxide thickness of about 1 nm, which could be grown to 8 nm by annealing. Remarkably, the contact resistances covered four orders of magnitude and were found to be exponentially dependent on the mean oxide thickness. Moreover, there is an optimum in the amount of a-C:H phase where the contact resistance drops very significantly and it is thus important to not only consider the mean oxide thickness. To explain the results, a model relying on surface chemistry and contact mechanics is presented. The lowest contact resistance of a nanocomposite matched that of a gold coating at 1 N load (vs. gold), and such performance has previously not been demonstrated for similar nanocomposite materials, highlighting their useful properties for electrical contact applications.

  • 128.
    Paul, Biplab
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Björk, Emma M.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering.
    Kumar, Aparabal
    Materials Science Centre, Indian Institute of Technology, Kharagpur 721302, India.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Nanoporous Ca3Co4O9 Thin Films for Transferable Thermoelectrics2018In: ACS applied energy materials, ISSN 2574-0962, Vol. 1, no 5, p. 2261-2268Article in journal (Refereed)
    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.

  • 129.
    Paul, Biplab
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Khranovskyy, Volodymyr
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Yakimova, Rositsa
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Donor-doped ZnO thin films on mica for fully-inorganic flexible thermoelectrics2019In: MATERIALS RESEARCH LETTERS, ISSN 2166-3831, Vol. 7, no 6, p. 239-243Article in journal (Refereed)
    Abstract [en]

    The development of fully-inorganic thin flexible materials is important for flexible thermoelectric applications in a wide temperature range, such as harvesting power from hot curved surfaces (e.g. hot pipes). Here, we investigate the thermoelectric properties of a series of ZnO:Ga,Al thin films with varying dopant concentration deposited on flexible mica substrate by atmospheric pressure metalorganic chemical vapor deposition. The films are bendable, while sustaining the high power factor, above 1 x 10(-4)Wm(-1)K(-2) for singly doped Zn0.99Ga0.01O film in a wide temperature range, from room temperature to 400 degrees C. IMPACT STATEMENTFor the first time we demonstrate here that ZnO-film-on-mica can be a promising n-type candidate for fully-inorganic flexible thermoelectrics, especially, for applications at elevated temperatures [GRAPHICS]

  • 130.
    Paul, Biplab
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Growth of CaxCoO2 Thin Films by A Two-Stage Phase Transformation from CaO-CoO Thin Films Deposited by Rf-Magnetron Reactive Cosputtering2019In: NANOMATERIALS, ISSN 2079-4991, Vol. 9, no 3, article id 443Article in journal (Refereed)
    Abstract [en]

    The layered cobaltates A(x)CoO(2) (A: alkali metals and alkaline earth metals) are of interest in the area of energy harvesting and electronic applications, due to their good electronic and thermoelectric properties. However, their future widespread applicability depends on the simplicity and cost of the growth technique. Here, we have investigated the sputtering/annealing technique for the growth of CaxCoO2 (x = 0.33) thin films. In this approach, CaO-CoO film is first deposited by rf-magnetron reactive cosputtering from metallic targets of Ca and Co. Second, the as-deposited film is reactively annealed under O-2 gas flow to form the final phase of CaxCoO2. The advantage of the present technique is that, unlike conventional sputtering from oxide targets, the sputtering is done from the metallic targets of Ca and Co; thus, the deposition rate is high. Furthermore, the composition of the film is controllable by controlling the power at the targets.

  • 131.
    Paul, Biplab
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Nanostructural Tailoring to Induce Flexibility in Thermoelectric Ca3Co4O9 Thin Films2017In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, no 30, p. 25308-25316Article in journal (Refereed)
    Abstract [en]

    Because of their inherent rigidity and brittleness, inorganic materials have seen limited use in flexible thermoelectric applications. On the other hand, for high output power density and stability, the use of inorganic materials is required. Here, we demonstrate a concept of fully inorganic flexible thermoelectric thin films with Ca3Co4O9-on-mica. Ca3Co4O9 is promising not only because of its high Seebeck coefficient and good electrical conductivity but also because of the abundance, low cost, and nontoxicity of its constituent raw materials. We show a promising nanostructural tailoring approach to induce flexibility in inorganic thin-film materials, achieving flexibility in nanostructured Ca3Co4O9 thin films. The films were grown by thermally induced phase transformation from CaO-CoO thin films deposited by reactive rf-magnetron cosputtering from metallic targets of Ca and Co to the final phase of Ca3Co4O9 on a mica substrate. The pattern of nanostructural evolution during the solid-state phase transformation is determined by the surface energy and strain energy contributions, whereas different distributions of CaO and CoO phases in the as-deposited films promote different nanostructuring during the phase transformation. Another interesting fact is that the Ca3Co4O9 film is transferable onto an arbitrary flexible platform from the parent mica substrate by etch-free dry transfer. The highest thermoelectric power factor obtained is above 1 x 10(-4) W m(-1) K-2 in a wide temperature range, thus showing low-temperature applicability of this class of materials.

  • 132.
    Paul, Biplab
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Schroeder, Jeremy Leroy
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Kerdsongpanya, Sit
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    van Nong, Ngo
    Risö-DTU, Denmark.
    Schell, Norbert
    Helmholtz-Zentrum Geestacht, Germany.
    Ostach, Daniel
    Helmholtz-Zentrum Geestacht, Germany.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Birch, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Mechanism of Formation of the Thermoelectric Layered Cobaltate Ca3Co4O9 by Annealing of CaO-CoO Thin Films2015In: Advanced Electronic Materials, ISSN 2199-160X, Vol. 1, no 3, article id 1400022Article in journal (Refereed)
    Abstract [en]

    The layered cobaltate Ca3Co4O9 is of interest for energy-harvesting and heat-conversion applications because of its good thermoelectric properties and the fact that the raw materials Ca and Co are nontoxic, abundantly available, and inexpensive. While single-crystalline Ca3Co4O9 exhibits high Seebeck coefficient and low resistivity, its widespread use is hampered by the fact that single crystals are too small and expensive. A promising alternative approach is the growth of highly textured and/or epitaxial Ca3Co4O9 thin films with correspondingly anisotropic properties. Here, we present a two-step sputtering/annealing method for the formation of highly textured virtually phase-pure Ca3Co4O9 thin films by reactive cosputtering from Ca and Co targets followed by an annealing process at 730 °C under O2-gas flow. The thermally induced phase transformation mechanism is investigated by in situ time-resolved annealing experiments using synchrotron-based 2D X-ray diffraction (XRD) as well as ex situ annealing experiments and standard lab-based XRD. By tuning the proportion of initial CaO and CoO phases during film deposition, the method enables synthesis of Ca3Co4O9 thin films as well as CaxCoO2. With this method, we demonstrate production of epitaxial Ca3Co4O9 thin films with in-plane electrical resistivity of 6.44 mΩ cm and a Seebeck coefficient of 118 μV K−1 at 300 K.

  • 133.
    Pedersen, K
    et al.
    University of Aarhus.
    Bottiger, J
    University of Aarhus.
    Sridharan, M
    University of Aarhus.
    Sillassen, M
    University of Aarhus.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Texture and microstructure of Cr2O3 and (Cr,Al)2O3 thin films deposited by reactive inductively coupled plasma magnetron sputtering2010In: THIN SOLID FILMS, ISSN 0040-6090, Vol. 518, no 15, p. 4294-4298Article in journal (Refereed)
    Abstract [en]

    Cr2O3 and (Cr,Al)(2)O-3 films were grown using reactive dc and inductively coupled plasma magnetron sputtering at substrate temperatures of 300-450 degrees C. For pure chromia, alpha-Cr2O3 films with fiber texture were grown; the out-of-plane texture could be controlled from andlt; 0001 andgt; to andlt;10andlt;(1)over barandgt;4andgt;. The former texture was obtained as a consequence of competitive growth with no applied bias or inductively coupled plasma, while the latter was obtained at moderate bias ( - 50 V), probably due to recrystallization driven by ion-bombardment-induced strain. By reactive codeposition of Cr and Al, a corundum-structured metastable solid solution alpha-(Cr,Al)(2)O-3 with Cr/Al ratios of 2-10 was grown with a dense, fine-grained morphology. Hardness and reduced elastic modulus values were in the ranges 24-27 GPa and 190-230 GPa, respectively.

  • 134.
    Pilemalm, Robert
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Pourovskii, Leonid
    Centre de Physique Théorique, Ecole Polytechnique, CNRS, Université Paris-Saclay, Route de Saclay, FR-91128 Palaiseau, France / Collège de France, 11 place Marcelin Berthelot, FR-75005 Paris, France.
    Mosyagin, Igor
    Materials Modeling and Development Laboratory, NUST “MISIS”, RU-119991 Moscow, Russia.
    Simak, Sergei
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Thermodynamic Stability, Thermoelectric, Elastic and Electronic Structure Properties of ScMN2-Type (M = V, Nb, Ta) Phases Studied by ab initio Calculations2019In: Condensed Matter, ISSN 2410-3896, Vol. 4, no 2, article id 36Article in journal (Refereed)
    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.

  • 135.
    Pilemalm, Robert
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Simak, Sergei
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    The Effect of Point Defects on the Electronic Density of States of ScMN2-Type (M = V, Nb, Ta) Phases2019In: Condensed Matter, ISSN 2410-3896, Vol. 4, no 3, article id 70Article in journal (Refereed)
    Abstract [en]

    ScMN2-type (M = V, Nb, Ta) phases are layered materials that have been experimentally reported for M = Ta and Nb. They are narrow-bandgap semiconductors with potentially interesting thermoelectric properties. Point defects such as dopants and vacancies largely affect these properties, motivating the need to investigate these effects. In particular, asymmetric peak features in the density of states (DOS) close to the highest occupied state is expected to increase the Seebeck coefficient. Here, we used first principles calculations to study the effects of one vacancy or one C, O, or F dopant on the DOS of the ScMN2 phases. We used density functional theory to calculate formation energy and the density of states when a point defect is introduced in the structures. In the DOS, asymmetric peak features close to the highest occupied state were found as a result of having a vacancy in all three phases. Furthermore, one C dopant in ScTaN2, ScNbN2, and ScVN2 implies a shift of the highest occupied state into the valence band, while one O or F dopant causes a shift of the highest occupied state into the conduction band.

  • 136.
    Pilemalm, Robert
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Simak, Sergey
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Effects of high pressure on ScMN2-type (M = V, Nb, Ta) phases studied by density functional theory2019In: Results in Physics, ISSN 2211-3797, Vol. 13, article id 102293Article in journal (Refereed)
    Abstract [en]

    ScMN2-type (M = V, Nb, Ta) phases are layered materials that have been experimentally reported for M = Ta and Nb, but their high-pressure properties have not been studied. Here, we have used first-principles calculations to study their thermodynamic stability, elastic and electronic properties at high-pressure. We have used density functional theory to calculate the formation enthalpy relative to the competing binary phases, electronic density of states and elastic constants (c(ij)), bulk (B), shear (G) and Youngs (E) modulus as the pressure is varied from 0 to 150 GPa. Our results show that when the pressure increases from 0 to 150 GPa, elastic constants, bulk, shear and elastic moduli increase in the range 53-216% for ScTaN2, 72-286% for ScNbN2, and 61-317% for ScVN2.

  • 137.
    Rech, S
    et al.
    Veneto Nanotech ScpA, Italy.
    Surpi, A
    Veneto Nanotech ScpA, Italy.
    Vezzu, S
    Veneto Nanotech ScpA, Italy.
    Patelli, A
    Veneto Nanotech ScpA, Italy.
    Trentin, A
    Veneto Nanotech ScpA, Italy.
    Glor, J
    Sandvik Mat Technology, Sweden.
    Frodelius, Jenny
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Cold-spray deposition of Ti2AlC coatings2013In: Vacuum, ISSN 0042-207X, E-ISSN 1879-2715, Vol. 94, p. 69-73Article in journal (Refereed)
    Abstract [en]

    Ti2AlC coatings have been fabricated by cold-spray deposition. The microstructure evolution as a function of basic spray parameters temperature and pressure onto AA6060 aluminium alloy and 1.0037 steel substrates has been studied. Adherent and dense 50–80 μm thick Ti2AlC coatings were deposited on soft AA6060 substrates under gas temperature and pressure of 600 °C and 3.4 MPa, respectively, whilst comparable results were obtained on harder 1.0037 steel by using higher temperature (800 °C) and pressure (3.9 MPa).

  • 138. Rester, M.
    et al.
    Neidhardt, Jörg
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Eklund, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Emmerlich, Jens
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Ljungcrantz, H.
    Hultman, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Mitterer, C.
    Annealing studies of nanocomposite Ti-Si-C thin films with respect to phase stability and tribological performance2006In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 429, no 1-2, p. 90-95Article in journal (Refereed)
    Abstract [en]

    Nanocomposite Ti-Si-C thin films were deposited by dc magnetron sputtering from a Ti3SiC2 target onto Si(1 0 0) and high-speed steel substrates at 300 °C. The as-deposited films consisted of nanocrystalline (nc-) TiCx and amorphous (a-) SiCx, as determined by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Annealing in vacuum up to 1450 °C resulted in improved crystallinity and a decreased volume fraction of the amorphous phase. Additionally, differential scanning calorimetry (DSC) was used to monitor heat flows connected to the respective reactions in the material, where a broad exothermic peak attributed to grain growth of crystalline TiCx appeared, while an exothermic reaction related to the formation of Ti3SiC2 was not detected. Tribological testing in a ball-on-disk setup was conducted at room temperature, 500 and 700 °C against an alumina counterpart. The room temperature measurement resulted in a coefficient of friction value of 0.8, at elevated temperatures the coefficient of friction decreased to 0.4. © 2006 Elsevier B.V. All rights reserved.

  • 139.
    Scabarozi, T H
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Hettinger, J D
    Rowan University.
    Lofland, S E
    Rowan University.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Jensen, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Epitaxial growth and electrical-transport properties of Ti(7)Si(2)C(5) thin films synthesized by reactive sputter-deposition2011In: Scripta Materialia, ISSN 1359-6462, E-ISSN 1872-8456, Vol. 65, no 9, p. 811-814Article in journal (Refereed)
    Abstract [en]

    Epitaxial predominantly phase-pure Ti(7)Si(2)C(5) thin films were grown onto Al(2)O(3)(0 0 0 1) by reactive magnetron sputtering. The c-axis lattice constant is similar to 60.2 angstrom; the Ti(7)Si(2)C(5) unit cell comprises alternating Ti(3)SiC(2)-like and Ti(4)SiC(3)-like half-unit-cell stacking repeated three times. Elastic recoil detection analysis showed a few percent of nitrogen in the films from the acetylene gas used. The nitrogen-induced stabilization mechanism for Ti(7)Si(2)C(5) relative to Ti(3)SiC(2) and Ti(4)SiC(3) is discussed. Electrical-transport measurements showed metallic temperature dependence and a room-temperature resistivity of similar to 45 mu Omega cm.

  • 140.
    Scabarozi, T.H.
    et al.
    Department of Materials Engineering, Drexel University, Philadelphia, PA 19104, United States, Department of Physics and Astronomy, Rowan University, Glassboro, NJ 08028, United States.
    Eklund, Per
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Emmerlich, Jens
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Högberg, Hans
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Meehan, T.
    Department of Physics and Astronomy, Rowan University, Glassboro, NJ 08028, United States.
    Finkel, P.
    Department of Physics and Astronomy, Rowan University, Glassboro, NJ 08028, United States.
    Barsoum, M.W.
    Department of Materials Engineering, Drexel University, Philadelphia, PA 19104, United States.
    Hettinger, J.D.
    Department of Physics and Astronomy, Rowan University, Glassboro, NJ 08028, United States.
    Hultman, Lars
    Linköping University, The Institute of Technology. Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics.
    Lofland, S.E.
    Department of Physics and Astronomy, Rowan University, Glassboro, NJ 08028, United States.
    Weak electronic anisotropy in the layered nanolaminate Ti 2 GeC2008In: Solid State Communications, ISSN 0038-1098, E-ISSN 1879-2766, Vol. 146, no 11-12, p. 498-501Article in journal (Refereed)
    Abstract [en]

    We have investigated the anisotropy in electronic transport of the layered ternary Ti2GeC by comparing the results of measurements on c-axis oriented epitaxial thin-film and polycrystalline bulk samples. The electrical conductivities, Hall coefficients, and magnetoresistances were analyzed within a multi-band framework. An adequate description of the magnetotransport data on the film with the highest mobility required the use of the explicit field-dependent conductivity tensor with three conduction bands. The analysis indicated that n ˜ p, although with n ˜ 3.5 × 1027 m- 3. The ratio of the a- to c-axis conductivities is small and contrary to theoretical predictions. © 2008 Elsevier Ltd. All rights reserved.

  • 141.
    Schramm, Isabella
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering. Saarland University, Germany.
    Pauly, C.
    Saarland University, Germany.
    Johansson Jöesaar, Mats P
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering. SECO Tools AB, Sweden.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Schmauch, J.
    Saarland University, Germany.
    Muecklich, F.
    Saarland University, Germany.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering.
    Solid state formation of Ti4AlN3 in cathodic arc deposited (Ti1-xAlx)N-y alloys2017In: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 129, p. 268-277Article in journal (Refereed)
    Abstract [en]

    Reactive cathodic arc deposition was used to grow substoichiometric solid solution cubic c-(Ti1-xAlx)N-y thin films. The films were removed from the substrate and then heated in an argon environment to 1400 degrees C. Via solid state reactions, formation of MAX phase Ti4AlN3 was obtained. Additional phases such as Ti2AlN, c-TiN, w-AIN, Al5Ti2 and Al3Ti were also present during the solid state reaction. Ti4AlN3 formation was observed in samples with an Al metal fraction x amp;lt; 0.63 and a nitrogen content 0.4 amp;lt; y amp;lt; 0.6. Regardless of the initial composition, formation of Ti4AlN3 started in Ti2AlN crystal plates in the temperature range between 1200 and 1400 degrees C. Accompanying the onset of Ti4AlN3 was the presence of an intermediate structure identified as Ti6Al2N4, consisting of alternating layers of intergrown Ti2AlN and Ti4AlN3 phases with a half-unit-cell stacking. We suggest that the formation of Ti4AlN3 occurred via intercalation of aluminum and nitrogen along the basal plane accompanied by a simultaneous detwinning process. In addition we propose that this formation mechanism can be used to obtain MAX phases of high n order. (C) 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  • 142.
    Shu, Rui
    et al.
    Chinese Academic Science, Peoples R China; University of Chinese Academic Science, Peoples R China.
    Ge, Fangfang
    Chinese Academic Science, Peoples R China.
    Meng, Fanping
    Chinese Academic Science, Peoples R China.
    Li, Peng
    Chinese Academic Science, Peoples R China.
    Wang, Ji
    Chinese Academic Science, Peoples R China.
    Huang, Qing
    Chinese Academic Science, Peoples R China.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Huang, Feng
    Chinese Academic Science, Peoples R China.
    One-step synthesis of polycrystalline V2AlC thin films on amorphous substrates by magnetron co-sputtering2017In: Vacuum, ISSN 0042-207X, E-ISSN 1879-2715, Vol. 146, p. 106-110Article in journal (Refereed)
    Abstract [en]

    We prepared V-Al-C films on glass and silicon (with native SiO2 layer) substrates using magnetron co-sputtering at 600 degrees C. The composition and microstructure of these films were characterized by Rutherford backscattering spectrometry, X-ray diffraction, Raman spectroscopy, and transmission electron microscopy. Polycrystalline V2AlC phase was obtained in the films with nearly stoichiometric composition. The microstructural evolution includes random nucleation at the film/substrate interface, competitive growth resulting in a (110) preferred orientation with increasing thickness. The mechanism for crystallization could be understood in terms of polymorphic crystallization. The results show that polycrystalline MAX-phase V2AlC could be directly synthesized on amorphous substrates. (C) 2017 Elsevier Ltd. All rights reserved.

  • 143.
    Si, Xiaoyang
    et al.
    Chinese Academic Science, Peoples R China; Shanghai University, Peoples R China.
    Li, Mian
    Chinese Academic Science, Peoples R China; University of Chinese Academic Science, Peoples R China.
    Chen, Fanyan
    Chinese Academic Science, Peoples R China.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Xue, Jianming
    Peking University, Peoples R China.
    Huang, Feng
    Chinese Academic Science, Peoples R China.
    Du, Shiyu
    Chinese Academic Science, Peoples R China.
    Huang, Qing
    Chinese Academic Science, Peoples R China.
    Effect of carbide interlayers on the microstructure and properties of graphene-nanoplatelet-reinforced copper matrix composites2017In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 708, p. 311-318Article in journal (Refereed)
    Abstract [en]

    Copper matrix composites reinforced with carbide-coated graphene nanoplatelets (GNPs) were investigated in order to understand the role of the interlayers on the thermal, electrical, mechanical and electro-tribological properties of the composites. The TiC or VC coatings were formed in situ on the two sides of GNPs through a controllable reaction in molten salts. Compared with bare GNPs composites, the bonding between the GNPs and copper was improved. Accordingly, the tensile strength and the fracture elongation of Cu/GNPs composites with an interlayer were enhanced by strengthened interfacial bonding. Furthermore, the wear resistance of Cu/GNPs composites was remarkably improved.

  • 144.
    Sillassen, M
    et al.
    University of Aarhus.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Pryds, N
    Technical University of Denmark.
    Bonanos, N
    Technical University of Denmark.
    Bottiger, J
    University of Aarhus.
    Concentration-dependent ionic conductivity and thermal stability of magnetron-sputtered nanocrystalline scandia-stabilized zirconia2010In: SOLID STATE IONICS, ISSN 0167-2738, Vol. 181, no 23-24, p. 1140-1145Article in journal (Refereed)
    Abstract [en]

    Nanocrystalline (nc) scandia-stabilized zirconia (SSZ) electrolytes with scandia contents of 5.9 to 15.9 mol% ere synthesized by reactive magnetron sputtering. For scandia content andgt;= 9.1 mol%, the as-deposited films were pure cubic phase with andlt; 111 andgt; texture, while traces of tetragonal phase was found for lower Sc content. Single-line profile analysis of the 111 X-ray diffraction peak yielded an out-of-plane grain size of similar to 10 nm and a microstrain of 2.0-2.2%, regardless of scandia content, for films deposited at 400 degrees C and a bias of -70 V. Films deposited at higher bias voltages showed a reduced grain size, yielding a grain size of similar to 6 nm and a microstrain of similar to 2.5% at -200 V and -250 V with additional incorporation of argon. Temperature-dependent impedance spectroscopy of the SSZ films showed that the in-plane ionic conductivity had a maximum close to 10.7 mol% and decreased almost an order of magnitude as the scandia - content was increased to 15.9 mol%. The activation energy for oxygen ion migration was determined to be between 130-1.43 eV. In addition, no dependence on grain size was observed. The above observations suggest a bulk mechanism for ionic conduction.

  • 145.
    Sillassen, M
    et al.
    University of Aarhus.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Pryds, N
    Technical University of Denmark.
    Bottiger, J
    University of rhus.
    Effects of dopant concentration and impurities on the conductivity of magnetron-sputtered nanocrystalline yttria-stabilized zirconia2010In: SOLID STATE IONICS, ISSN 0167-2738, Vol. 181, no 19-20, p. 864-867Article in journal (Refereed)
    Abstract [en]

    Cubic yttria-stabilized zirconia (YSZ) films with yttria concentrations of 8.7, 9.9, and 11 mol% have been deposited by reactive pulsed DC magnetron from Zr-Y alloy targets. The overall microstructure and texture in the films showed no dependence on the yttria concentration. Films deposited at floating potential had a andlt; 111 andgt; texture. Single-line profile analysis of the 111 X-ray diffraction peak yielded a grain size of similar to 18 nm and a microstrain of similar to 2%. regardless of deposition temperature. Films deposited at 400 degrees C and selected bias voltages in the range from -70 V to -200 V showed a reduced grain size for higher bias voltages, yielding a grain size of similar to 7 nm and a microstrain of similar to 2.5% at a bias voltage of -200 V with additional incorporation of argon. Furthermore, the effect of impurities on the ionic conductivity has been investigated, since Hf impurities were found in the samples with yttria concentrations of 8.7, and 9.9 mol%. Temperature-dependent impedance spectroscopy of the YSZ films, deposited at 400 degrees C and floating potential, showed no variation of the in-plane ionic conductivity with yttria concentration. However, for films deposited at 400 degrees C and a bias -70 V. the in-plane ionic conductivity decreased systematically for samples with yttria concentrations of 8.7 and 9.9 mol% compared to the sample with 11 mol% yttria. This suggests that ionic conduction is not a purely bulk mechanism, but mainly related to the grain boundaries. The activation energy for oxygen ion migration was determined to be between 1.25 and 1.32 eV.

  • 146.
    Sillassen, M.
    et al.
    University of Aarhus, Department of Physics and Astronomy and Interdisciplinary Nanoscience Center (iNANO).
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Sridharan, M.
    University of Aarhus, Department of Physics and Astronomy and Interdisciplinary Nanoscience Center (iNANO).
    Pryds, N.
    Technical University of Denmark, Riso National Laboratory for Sustainable Energy.
    Bonanos, N.
    Technical University of Denmark, Riso National Laboratory for Sustainable Energy.
    Bottiger, J.
    University of Aarhus, Department of Physics and Astronomy and Interdisciplinary Nanoscience Center (iNANO).
    Ionic conductivity and thermal stability of magnetron-sputtered nanocrystalline yttria-stabilized zirconia2009In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 105, no 10, p. 104907-Article in journal (Refereed)
    Abstract [en]

    Thermally stable, stoichiometric, cubic yttria-stabilized zirconia (YSZ) thin-film electrolytes have been synthesized by reactive pulsed dc magnetron sputtering from a Zr-Y (80/20 at. %) alloy target. Films deposited at floating potential had a ‹111› texture. Single-line profile analysis of the 111 x-ray diffraction peak yielded a grain size of ~20 nm and a microstrain of ~2% regardless of deposition temperature. Films deposited at 400 °C and selected bias voltages in the range from -70 to -200 V showed a reduced grain size for higher bias voltages, yielding a grain size of ~6 nm and a microstrain of ~2.5% at bias voltages of -175 and -200 V with additional incorporation of argon. The films were thermally stable; very limited grain coarsening was observed up to an annealing temperature of 800 °C. Temperature-dependent impedance spectroscopy analysis of the YSZ films with Ag electrodes showed that the in-plane ionic conductivity was within one order of magnitude higher in films deposited with substrate bias corresponding to a decrease in grain size compared to films deposited at floating potential. This suggests that there is a significant contribution to the ionic conductivity from grain boundaries. The activation energy for oxygen ion migration was determined to be between 1.14 and 1.30 eV.

     

  • 147.
    Sillassen, Michael
    et al.
    University of Aarhus.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Pryds, Nini
    Technical University of Denmark.
    Johnson, Erik
    Technical University of Denmark.
    Helmersson, Ulf
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics . Linköping University, The Institute of Technology.
    Bottiger, Jorgen
    University of Aarhus.
    Low-Temperature Superionic Conductivity in Strained Yttria-Stabilized Zirconia2010In: ADVANCED FUNCTIONAL MATERIALS, ISSN 1616-301X, Vol. 20, no 13, p. 2071-2076Article in journal (Refereed)
    Abstract [en]

    Very high lateral ionic conductivities in epitaxial cubic yttria-stabilized zirconia (YSZ) synthesized on single-crystal SrTiO3and MgO substrates by reactive direct current magnetron sputtering are reported. Superionic conductivities (i.e., ionic conductivities of the order similar to 1 Omega(-1)cm(-1)) are observed at 500 degrees C for 58-nm-thick films on MgO. The results indicate a superposition of two parallel contributions - one due to bulk conductivity and one attributable to conduction along the film substrate interface. Interfacial effects dominate the conductivity at low temperatures (andlt;350 degrees C), showing more than three orders of magnitude enhancement compared to bulk YSZ. At higher temperatures, a more bulk-like conductivity is observed. The films have a negligible grain-boundary network, thus ruling out grain boundaries as a pathway for ionic conduction. The observed enhancement in lateral ionic conductivity is caused by a combination of misfit dislocation density and elastic strain in the interface. These very high ionic conductivities in the temperature range 150-500 degrees C are of great fundamental importance but may also be technologically relevant for low-temperature applications.

  • 148.
    Sun, Y
    et al.
    University of Aarhus.
    Johnsen, S
    University of Aarhus.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Sillassen, M
    University of Aarhus.
    Bottiger, J
    University of Aarhus.
    Oeschler, N
    Max Planck Institute.
    Sun, P
    Max Planck Institute.
    Steglich, F
    Max Planck Institute.
    Iversen, B B
    University of Aarhus.
    Thermoelectric transport properties of highly oriented FeSb2 thin films2009In: JOURNAL OF APPLIED PHYSICS, ISSN 0021-8979, Vol. 106, no 3Article in journal (Refereed)
    Abstract [en]

    Highly textured FeSb2 films were produced on quartz wafers by a sputtering method. Their resistivity and Seebeck coefficient (S) were measured and a maximum absolute value of S similar to 160 mu V K-1 at 50 K was obtained. Hall measurements were employed to study the charge carrier concentrations and Hall mobilities of the FeSb2 films. By comparing with the transport properties of FeSb2 single crystals and an extrinsically doped FeSb1.98Te0.02 single crystal, the thermoelectric properties of the FeSb2 films are demonstrated to be dominated by the intrinsic properties of FeSb2 at a high charge carrier concentration.

  • 149.
    Sønderby, Steffen
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Aijaz, Asim
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, The Institute of Technology.
    Helmersson, Ulf
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, The Institute of Technology.
    Sarakinos, Kostas
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, The Institute of Technology.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, The Institute of Technology.
    Deposition of yttria-stabilized zirconia thin films by high power impulse magnetron sputtering and pulsed magnetron sputtering2014In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 240, p. 1-6Article in journal (Refereed)
    Abstract [en]

    Yttria-stabilized zirconia (YSZ) thin films were reactively sputter-deposited by high power impulse magnetron sputtering (HiPIMS) and pulsed direct current magnetron sputtering (DCMS). The use of substrate bias voltage was studied in both modes of deposition as a process parameter to promote the growth of dense and less columnar films. Films were deposited on both Si(100) and NiO-YSZ fuel cell anodes. The texture, morphology and composition of the deposited films were investigated with regard to their application as thin electrolytes for solid oxide fuel cells (SOFCs). Independent of the deposition mode the films were found to be stoichiometric. The application of substrate bias voltage had opposite effects on texture and crystallinity of films deposited by pulsed DCMS and HiPIMS. Films deposited by pulsed DCMS became highly crystalline and <220> textured at high bias voltage whereas bias applied to HiPIMS deposited films disrupted crystal growth leading to deterioration of crystallinity. Comparing film morphology, it was found that pulsed DCMS films were columnar and contained voids regardless of the applied substrate bias. When depositing by HiPIMS a window of operation at a bias voltage of -25 V to -50 V was found in which it is possible to deposit non-columnar thin films without voids and cracks as desired for SOFC applications. 

  • 150.
    Sønderby, Steffen
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. Danish Technological Institute.
    Christensen, Bjarke H
    Danish Technological Institute.
    Almtoft, Klaus P.
    Danish Technological Institute.
    Nielsen, Lars P.
    Danish Technological Institute.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Industrial-scale high power impulse magnetron sputtering of yttria-stabilized zirconia on porous NiO/YSZ fuel cell anodes2015In: SURFACE & COATINGS TECHNOLOGY, ISSN 0257-8972, Vol. 281, p. 150-156Article in journal (Refereed)
    Abstract [en]

    Yttria-stabilized zirconia (YSZ) thin films are reactively sputter-deposited by high power impulse magnetron sputtering (HiPIMS) in an industrial setup on porous NiO/YSZ fuel cell anodes. The influence of deposition pressure, peak power and substrate bias on the deposition rate and film morphology is studied. It is seen that depositing at increasing the deposition pressure from ~370 mPa to ~750 mPa results in a 64 % increase in the deposition rate and denser film. Films are deposited at peak power densities ranging from 0.4 kW/cm2 to 1.1 kW/cm2. By increasing the peak power density the degree of ionization degree of both Ar and sputtered metallic species is significantly increased which results in denser films as open column boundaries are removed. The increase in peak power also results in a significant drop in deposition rate. By combining a peak power density of ~0.6 kW/cm2 with the application of -180 V substrate bias voltage a homogenous and essentially columnless coating can be deposited. These results demonstrate HiPIMS deposition is capable of producing dense, YSZ coatings on porous substrates as needed for solid oxide fuel cell application. 

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