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  • 1.
    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.

  • 2.
    Calamba, Katherine
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering. Univ Lorraine, France.
    Pierson, J. F.
    Univ Lorraine, France.
    Bruyere, S.
    Univ Lorraine, France.
    Le Febvrier, Arnaud
    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.
    Barrirero, Jenifer
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering. Saarland Univ, Germany.
    Muecklich, F.
    Saarland Univ, Germany.
    Boyd, Robert
    Linköping University, Department of Physics, Chemistry and Biology, Plasma and Coating Physics. Linköping University, Faculty of Science & Engineering.
    Jöesaar Johansson, Mats
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering. SECO Tools AB, Sweden.
    Odén, Magnus
    Linköping University, Department of Physics, Chemistry and Biology, Nanostructured Materials. Linköping University, Faculty of Science & Engineering.
    Dislocation structure and microstrain evolution during spinodal decomposition of reactive magnetron sputtered heteroepixatial c-(Ti-0.37,Al-0.63)N/c-TiN films grown on MgO(001) and (111) substrates2019In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 125, no 10, article id 105301Article in journal (Refereed)
    Abstract [en]

    Heteroepitaxial c-(Ti-0.37,Al-0.63)N thin films were grown on MgO(001) and MgO(111) substrates using reactive magnetron sputtering. High resolution high-angle annular dark-field scanning transmission electron micrographs show coherency between the film and the substrate. In the as-deposited state, x-ray diffraction reciprocal space maps show a strained epitaxial film. Corresponding geometric phase analysis (GPA) deformation maps show a high stress in the film. At elevated temperature (900 degrees C), the films decompose to form iso-structural coherent c-Al- and c-TiN-rich domains, elongated along the elastically soft amp;lt;100amp;gt; directions. GPA analysis reveals that the c-TiN domains accommodate more dislocations than the c-AlN domains. This is because of the stronger directionality of the covalent bonds in c-AlN compared with c-TiN, making it more favorable for the dislocations to accumulate in c-TiN. The defect structure and strain generation in c-(Ti,Al)N during spinodal decomposition is affected by the chemical bonding state and elastic properties of the segregated domains.

  • 3.
    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]

  • 4.
    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).

  • 5.
    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.

  • 6.
    Halim, Joseph
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Persson, Ingemar
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Moon, Eun Ju
    SUNY Buffalo, NY 14260 USA.
    Kuhne, Philipp
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. Linköping University, Faculty of Science & Engineering.
    Darakchieva, Vanya
    Linköping University, Department of Physics, Chemistry and Biology, Semiconductor Materials. 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.
    Eklund, Per
    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.
    Barsoum, Michel W.
    Drexel Univ, PA 19104 USA.
    Electronic and optical characterization of 2D Ti2C and Nb2C (MXene) thin films2019In: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 31, no 16, article id 165301Article in journal (Refereed)
    Abstract [en]

    Two-dimensional (2D) transition metal carbides and/or nitrides (MXenes) are a new class of 2D materials, with extensive opportunities for property tailoring due to the numerous possibilities for varying chemistries and surface terminations. Here, Ti2AlC and Nb2AlC MAX phase epitaxial thin films were deposited on sapphire substrates by physical vapor deposition. The films were then etched in LiF/HCl solutions, yielding Li-intercalated, 2D Ti2CTz and Nb2CTz films, whose terminations, transport and optical properties were characterized. The former exhibits metallic conductivity, with weak localization below 50 K. In contrast, the Nb-based film exhibits an increase in resistivity with decreasing temperature from RT down to 40K consistent with variable range hopping transport. The optical properties of both films were determined from spectroscopic ellipsometry in the 0.75 to 3.50 eV range. The results for Ti2Clz films confirm the metallic behavior. In contrast, no evidence of metallic behavior is observed for the Nb2CT(z) film. The present work therefore demonstrates that one fruitful approach to alter the electronic and optical properties of MXenes is to change the nature of the transition metal.

  • 7.
    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.

  • 8.
    Ekström, Erik
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Le Febvrier, Arnaud
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Fournier, Daniele
    Sorbonne Univ, France.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Ene, Vladimir-Lucian
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering. Univ Politehn Bucuresti, Romania.
    Van Nong, Ngo
    Tech Univ Denmark, Denmark.
    Eriksson, Fredrik
    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.
    Paul, Biplab
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Formation mechanism and thermoelectric properties of CaMnO3 thin films synthesized by annealing of Ca0.5Mn0.5O films2019In: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 54, no 11, p. 8482-8491Article in journal (Refereed)
    Abstract [en]

    A two-step synthesis approach was utilized to grow CaMnO3 on M-, R- and C-plane sapphire substrates. Radio-frequency reactive magnetron sputtering was used to grow rock-salt-structured (Ca, Mn)O followed by a 3-h annealing step at 800 degrees C in oxygen flow to form the distorted perovskite phase CaMnO3. The effect of temperature in the post-annealing step was investigated using x-ray diffraction. The phase transformation to CaMnO3 started at 450 degrees C and was completed at 550 degrees C. Films grown on R- and C-plane sapphire showed similar structure with a mixed orientation, whereas the film grown on M-plane sapphire was epitaxially grown with an out-of-plane orientation in the [202] direction. The thermoelectric characterization showed that the film grown on M-plane sapphire has about 3.5 times lower resistivity compared to the other films with a resistivity of 0.077cm at 500 degrees C. The difference in resistivity is a result from difference in crystal structure, single orientation for M-plane sapphire compared to mixed for R- and C-plane sapphire. The highest absolute Seebeck coefficient value is -350 mu VK-1 for all films and is decreasing with temperature.

  • 9.
    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.

  • 10.
    Ali, Sharafat
    et al.
    Linnaeus Univ, Sweden.
    Paul, Biplab
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Magnusson, Roger
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Ekström, Erik
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Pallier, Camille
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. RISE IVF, S-58188 Linkoping, Sweden.
    Jonson, Bo
    Linnaeus Univ, Sweden.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Birch, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Optical and mechanical properties of amorphous Mg-Si-O-N thin films deposited by reactive magnetron sputtering2019In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 372, p. 9-15Article in journal (Refereed)
    Abstract [en]

    In this work, amorphous thin films in Mg-Si-O-N system typically containing amp;gt; 15 at.% Mg and 35 at.% N were prepared in order to investigate especially the dependence of optical and mechanical properties on Mg composition. Reactive RF magnetron co-sputtering from magnesium and silicon targets were used for the deposition of Mg-Si-O-N thin films. Films were deposited on float glass, silica wafers and sapphire substrates in an Ar, N-2 and O-2 gas mixture. X-ray photoelectron spectroscopy, atomic force microscopy, scanning electron microscopy, spectroscopic ellipsometry, and nanoindentation were employed to characterize the composition, surface morphology, and properties of the films. The films consist of N and Mg contents up to 40 at.% and 28 at.%, respectively and have good adhesion to substrates and are chemically inert. The thickness and roughness of the films increased with increasing content of Mg. Both hardness (16-21 GPa) and reduced elastic modulus (120-176 GPa) are strongly correlated with the amount of Mg content. The refractive index up to 2.01 and extinction coefficient up to 0.18 were found to increase with Mg content. The optical band gap (3.1-4.3) decreases with increasing the Mg content. Thin film deposited at substrate temperature of 100 degrees C shows a lower value of hardness (10 GPa), refractive index (1.75), and higher values of reduced elastic modulus (124 GPa) as compared to the thin film deposited at 310 degrees C and 510 degrees C respectively, under identical synthesis parameters.

  • 11.
    Landälv, Ludvig
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. Sandvik Coromant AB, Stockholm, Sweden.
    Carlström, C-F
    Sandvik Coromant AB, Stockholm, Sweden.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Primetzhofer, D.
    Applied Nuclear Physics, Department of Physics and Astronomy, Uppsala University, Uppsala, Sweden.
    Jöesaar, M. J.
    SECO Tools AB, Fagersta, Sweden.
    Ahlgren, M.
    Sandvik Coromant AB, Stockholm, Sweden.
    Göthelid, E.
    Sandvik Coromant AB, Stockholm, Sweden.
    Alling, Björn
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical 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.
    Phase composition and transformations in magnetron-sputtered (Al,V)2O3 coatings2019In: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731Article in journal (Refereed)
    Abstract [en]

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

  • 12.
    Gharavi, Mohammad Amin
    et al.
    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.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Balke, B.
    Univ Stuttgart, Germany.
    Fournier, D.
    Sorbonne Univ, France.
    Le Febvrier, Arnaud
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Pallier, Camille
    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.
    Synthesis and characterization of single-phase epitaxial Cr2N thin films by reactive magnetron sputtering2019In: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 54, no 2, p. 1434-1442Article in journal (Refereed)
    Abstract [en]

    Cr2N is commonly found as a minority phase or inclusion in stainless steel, CrN-based hard coatings, etc. However, studies on phase-pure material for characterization of fundamental properties are limited. Here, Cr2N thin films were deposited by reactive magnetron sputtering onto (0001) sapphire substrates. X-ray diffraction and pole figure texture analysis show Cr2N (0001) epitaxial growth. Scanning electron microscopy imaging shows a smooth surface, while transmission electron microscopy and X-ray reflectivity show a uniform and dense film with a density of 6.6gcm(-3), which is comparable to theoretical bulk values. Annealing the films in air at 400 degrees C for 96h shows little signs of oxidation. Nano-indentation shows an elastic-plastic behavior with H=18.9GPa and E-r=265GPa. The moderate thermal conductivity is 12Wm(-1)K(-1), and the electrical resistivity is 70cm. This combination of properties means that Cr2N may be of interest in applications such as protective coatings, diffusion barriers, capping layers and contact materials.

  • 13.
    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.

  • 14.
    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
  • 15.
    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.

  • 16.
    Du, Yong
    et al.
    Shanghai Inst Technol, Peoples R China.
    Li, Jia
    Shanghai Inst Technol, Peoples R China.
    Xu, Jiayue
    Shanghai Inst Technol, Peoples R China.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Thermoelectric Properties of Reduced Graphene Oxide/Bi2Te3 Nanocomposites2019In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 12, no 12, article id 2430Article in journal (Refereed)
    Abstract [en]

    Reduced graphene oxide (rGO)/Bi2Te3 nanocomposite powders with different contents of rGO have been synthesized by a one-step in-situ reductive method. Then, rGO/Bi2Te3 nanocomposite bulk materials were fabricated by a hot-pressing process. The effect of rGO contents on the composition, microstructure, TE properties, and carrier transportation of the nanocomposite bulk materials has been investigated. All the composite bulk materials show negative Seebeck coefficient, indicating n-type conduction. The electrical conductivity for all the rGO/Bi2Te3 nanocomposite bulk materials decreased with increasing measurement temperature from 25 degrees C to 300 degrees C, while the absolute value of Seebeck coefficient first increased and then decreased. As a result, the power factor of the bulk materials first increased and then decreased, and a power factor of 1340 mu Wm(-1)K(-2) was achieved for the nanocomposite bulk materials with 0.25 wt% rGO at 150 degrees C.

  • 17.
    Zhou, Jie
    et al.
    Chinese Acad Sci, Peoples R China.
    Zha, Xian-Hu
    Chinese Acad Sci, Peoples R China.
    Yildizhan Özyar, Melike
    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.
    Xue, Jianming
    Peking Univ, Peoples R China.
    Liao, Meiyong
    NIMS, Japan.
    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.
    Huang, Qing
    Chinese Acad Sci, Peoples R China.
    Two-Dimensional Hydroxyl-Functionalized and Carbon-Deficient Scandium Carbide, ScCxOH, a Direct Band Gap Semiconductor2019In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 13, no 2, p. 1195-1203Article in journal (Refereed)
    Abstract [en]

    Two-dimensional (2D) materials have attracted intense attention in nanoscience and nanotechnology due to their outstanding properties. Among these materials, the emerging family of 2D transition metal carbides, carbonitrides, and nitrides (referred to as MXenes) stands out because of the vast available chemical space for tuning materials chemistry and surface termination, offering opportunities for property tailoring. Specifically, semiconducting properties are needed to enable utilization in optoelectronics, but direct band gaps are experimentally challenging to achieve in these 2D carbides. Here, we demonstrate the fabrication of 2D hydroxyl-functionalized and carbon-deficient scandium carbide, namely, ScCxOH, by selective etching of a layered parent ScAI(3)C(3) compound. The 2D configuration is determined as a direct band gap semiconductor, with an experimentally measured band gap approximated at 2.5 eV. Furthermore, this ScCxOH-based device exhibits excellent photoresponse in the ultraviolet-visible light region (responsivity of 0.125 A/W at 360 nm/10 V, and quantum efficiency of 43%). Thus, this 2D ScCxOH direct band gap semiconductor may find applications in visible light detectors, photocatalytic chemistry, and optoelectronic devices.

  • 18.
    Tureson, Nina
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Marteau, Marc
    Univ Poitiers, France.
    Cabioch, Thierry
    Univ Poitiers, France.
    Van Nong, Ngo
    Tech Univ Denmark, Denmark.
    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.
    Greczynski, Grzegorz
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Fournier, Daniele
    Sorbonne Univ, France.
    Singh, Niraj
    Indian Inst Technol Mandi, India.
    Soni, Ajay
    Indian Inst Technol Mandi, India.
    Belliard, Laurent
    Sorbonne Univ, France.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Le Febvrier, Arnaud
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Effect of ion-implantation-induced defects and Mg dopants on the thermoelectric properties of ScN2018In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 98, no 20, article id 205307Article in journal (Refereed)
    Abstract [en]

    For applications in energy harvesting and environmentally friendly cooling, and for power sources in remote or portable applications, it is desired to enhance the efficiency of thermoelectric materials. One strategy consists of reducing the thermal conductivity while increasing or retaining the thermoelectric power factor. An approach to achieve this is doping to enhance the Seebeck coefficient and electrical conductivity, while simultaneously introducing defects in the materials to increase phonon scattering. Here, we use Mg ion implantation to induce defects in epitaxial ScN (111) films. The films were implanted with Mg+ ions with different concentration profiles along the thickness of the film, incorporating 0.35 to 2.2 at. % of Mg in ScN. Implantation at high temperature (600 degrees C), with few defects due to the temperature, does not substantially affect the thermal conductivity compared to a reference ScN. Samples implanted at room temperature, in contrast, exhibited a reduction of the thermal conductivity by a factor of 3. The sample doped with 2.2 at. % of Mg also showed an increased power factor after implantation. This paper thus shows the effect of ion-induced defects on thermal conductivity of ScN films. High-temperature implantation allows the defects to be annealed out during implantation, while the defects are retained for room-temperature implanted samples, allowing for a drastic reduction in thermal conductivity.

  • 19.
    Du, Yong
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. Shanghai Inst Technol, Peoples R China.
    Chen, Jiageng
    Shanghai Inst Technol, Peoples R China.
    Liu, Xin
    Shanghai Inst Technol, Peoples R China.
    Lu, Chun
    Shenyang Aerosp Univ, Peoples R China.
    Xu, Jiayue
    Shanghai Inst Technol, Peoples R China.
    Paul, Biplab
    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.
    Flexible n-Type Tungsten Carbide/Polylactic Acid Thermoelectric Composites Fabricated by Additive Manufacturing2018In: Coatings, ISSN 2079-6412, Vol. 8, no 1, article id 25Article in journal (Refereed)
    Abstract [en]

    Flexible n-type tungsten carbide/polylactic acid (WC/PLA) composites were fabricated by additive manufacturing and their thermoelectric properties were investigated. The preparation of an n-type polymer-based thermoelectric composite with good stability in air atmosphere via additive manufacturing holds promise for application in flexible thermoelectric devices. For WC/PLA volume ratios varying from similar to 33% to 60%, the electrical conductivity of the composites increased from 10.6 to 42.2 S/cm, while the Seebeck coefficients were in the range -11 to -12.3 V/K. The thermal conductivities of the composites varied from similar to 0.2 to similar to 0.28 Wamp;lt;boldamp;gt;mamp;lt;/boldamp;gt;-1amp;lt;boldamp;gt;Kamp;lt;/boldamp;gt;-1 at similar to 300 K.

  • 20.
    Du, Yong
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. Shanghai Inst Technol, Peoples R China.
    Xu, Jiayue
    Shanghai Inst Technol, Peoples R China.
    Paul, Biplab
    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.
    Flexible thermoelectric materials and devices2018In: APPLIED MATERIALS TODAY, ISSN 2352-9407, Vol. 12, p. 366-388Article, review/survey (Refereed)
    Abstract [en]

    Thermoelectric generators (TEGs) can directly convert waste heat into electrical power. In the last few decades, most research on thermoelectrics has focused on inorganic bulk thermoelectric materials and corresponding devices, and their thermoelectric properties have been significantly improved. An emerging topic is flexible devices, where the use of bulk inorganic materials is precluded by their inherent rigidity. The purpose of this paper is to review the research progress on flexible thermoelectric materials and generators, including theoretical principles for TEGs, conducting polymer TE materials, nanocomposites comprised of inorganic nanostructures in polymer matrices and fully inorganic flexible TE materials in nanostructured thin films. Approaches for flexible TEGs and components are reviewed, and remaining challenges discussed. (C) 2018 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

  • 21.
    Lai, Chung-Chuan
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Tao, Quanzheng
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Fashandi, Hossein
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Wiedwald, Ulf
    Univ Duisburg Essen, Germany; Natl Univ Sci and Technol MISIS, Russia.
    Salikhov, Ruslan
    Univ Duisburg Essen, Germany.
    Farle, Michael
    Univ Duisburg Essen, Germany; Immanuel Kant Balt Fed Univ, Russia.
    Petruhins, Andrejs
    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.
    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.
    Rosén, Johanna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Magnetic properties and structural characterization of layered (Cr0.5Mn0.5)(2)AuC synthesized by thermally induced substitutional reaction in (Cr0.5Mn0.5)(2)GaC2018In: APL MATERIALS, ISSN 2166-532X, Vol. 6, no 2, article id 026104Article in journal (Refereed)
    Abstract [en]

    The magnetic properties of the new phase (Cr0.5Mn0.5)(2)AuC are compared to the known MAX-phase (Cr0.5Mn0.5)(2)GaC, where the former was synthesized by thermally induced substitution reaction of Au for Ga in (Cr0.5Mn0.5)(2)GaC. The reaction introduced a lattice expansion of similar to 3% along the c-axis, an enhancement of the coercive field from 30 mT to 140 mT, and a reduction of the Curie temperature and the saturation magnetization. Still, (Cr0.5Mn0.5)(2)AuC displays similar features in the magnetic field-and temperature-dependent magnetization curves as previously reported magnetic MAX phases, e.g., (Cr0.5Mn0.5)(2)GaC and (Mo0.5Mn0.5)(2)GaC. Thework suggests a pathway for tuning the magnetic properties of MAX phases. (c) 2018 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license.

  • 22.
    Wang, Ji
    et al.
    Chinese Acad Sci, Peoples R China.
    Liu, Shaoshuai
    Peking Univ, Peoples R China.
    Ren, Donglou
    Chinese Acad Sci, Peoples R China.
    Shao, Tao
    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, Rong
    East China Normal Univ, Peoples R China.
    Zhu, Yabin
    Chinese Acad Sci, Peoples R China.
    Huang, Feng
    Chinese Acad Sci, Peoples R China.
    Du, Shiyu
    Chinese Acad Sci, Peoples R China.
    Wang, Zhiguang
    Chinese Acad Sci, Peoples R China.
    Xue, Jianming
    Peking Univ, Peoples R China.
    Wang, Yugang
    Peking Univ, Peoples R China.
    Huang, Qing
    Chinese Acad Sci, Peoples R China.
    Microstructural evolution of epitaxial Ti3AlC2 film on sapphire under ion irradiation and nanoindentation-induced deformation2018In: Journal of Nuclear Materials, ISSN 0022-3115, E-ISSN 1873-4820, Vol. 509, p. 181-187Article in journal (Refereed)
    Abstract [en]

    Feasibility of Ti3AlC2 phase as the protective coatings of accident tolerant fuels (ATFs) was investigated by means of ions irradiation, nanoindentation and transmission electron microscopy. Au ions irradiation was carried out on thin Ti3AlC2 film to simulate the high displacement damage induced by the energetic particles in the nuclear reactors. Nanoindentation on the Ti3AlC2 film was followed subsequently as a source of external stress to simulate the high pressure applied on the cladding in nuclear reactor cores of pressurized water reactors (PWRs). TEM was used to characterize the microstructural evolution of Ti3AlC2 film after irradiation and nanoindentation. TEM analysis shows that Ti3AlC2 film remains pristine layered structure and no amorphization was detected after irradiation to similar to 14 dpa. The combined nanoindentation and TEM show that no rupture and exfoliation of the Au-irradiated Ti3AlC2 film occur even the extern stress and total elongation induced by nanoindentation reach to 16.6 GPa and similar to 5%, respectively. The above results show good irradiation resistance and good ductility as well as excellent adhesion of the Ti3AlC2 coating on the substrate after high dose irradiation and under high external stress. This indicates the good feasibility of Ti3AlC2 thin films as the coatings of ATF claddings. (C) 2018 Elsevier B.V. All rights reserved.

    The full text will be freely available from 2020-06-30 12:27
  • 23.
    Gharavi, Mohammad Amin
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Kerdsongpanya, Sit
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. Rensselaer Polytech Inst, NY 12180 USA.
    Schmidt, Susann
    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.
    Nong, N. V
    Tech Univ Denmark, Denmark.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Balke, B.
    Johannes Gutenberg Univ Mainz, Germany.
    Fournier, D.
    UPMC Univ Paris 06, France.
    Belliard, L.
    UPMC Univ Paris 06, France.
    Le Febvrier, Arnaud
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Pallier, Camille
    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.
    Microstructure and thermoelectric properties of CrN and CrN/Cr2N thin films2018In: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 51, no 35, article id 355302Article in journal (Refereed)
    Abstract [en]

    CrN thin films with an N/Cr ratio of 95% were deposited by reactive magnetron sputtering onto (0001) sapphire substrates. X-ray diffraction and pole figure texture analysis show CrN (111) epitaxial growth in a twin domain fashion. By changing the nitrogen versus argon gas flow mixture and the deposition temperature, thin films with different surface morphologies ranging from grainy rough textures to flat and smooth films were prepared. These parameters can also affect the CrN(x )system, with the film compound changing between semiconducting CrN and metallic Cr2N through the regulation of the nitrogen content of the gas flow and the deposition temperature at a constant deposition pressure. Thermoelectric measurements (electrical resistivity and Seebeck coefficient), scanning electron microscopy, and transmission electron microscopy imaging confirm the changing electrical resistivity between 0.75 and 300 m omega cm, the changing Seebeck coefficient values between 140 and 230 mu VK-1, and the differences in surface morphology and microstructure as higher temperatures result in lower electrical resistivity while gas flow mixtures with higher nitrogen content result in single phase cubic CrN.

  • 24.
    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.

  • 25.
    Du, Yong
    et al.
    Shanghai Inst Technol, Peoples R China.
    Li, Haixia
    Shanghai Inst Technol, Peoples R China.
    Jia, Xuechen
    Shanghai Inst Technol, Peoples R China.
    Dou, Yunchen
    Shanghai Inst Technol, Peoples R China.
    Xu, Jiayue
    Shanghai Inst Technol, Peoples R China.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Preparation and Thermoelectric Properties of Graphite/poly(3,4-ethyenedioxythiophene) Nanocomposites2018In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 11, no 10, article id 2849Article in journal (Refereed)
    Abstract [en]

    Graphite/poly(3,4-ethyenedioxythiophene) (PEDOT) nanocomposites were prepared by an in-situ oxidative polymerization process. The electrical conductivity and Seebeck coefficient of the graphite/PEDOT nanocomposites with different content of graphite were measured in the temperature range from 300 K to 380 K. The results show that as the content of graphite increased from 0 to 37.2 wt %, the electrical conductivity of the nanocomposites increased sharply from 3.6 S/cm to 80.1 S/cm, while the Seebeck coefficient kept almost the same value (in the range between 12.0 V/K to 15.1 V/K) at 300 K, which lead to an increased power factor. The Seebeck coefficient of the nanocomposites increased from 300 K to 380 K, while the electrical conductivity did not substantially depend on the measurement temperature. As a result, a power factor of 3.2 Wm(-1) K-2 at 380 K was obtained for the nanocomposites with 37.2 wt % graphite.

  • 26.
    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

  • 27.
    Halim, Joseph
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Persson, Ingemar
    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.
    Sodium hydroxide and vacuum annealing modifications of the surface terminations of a Ti3C2 (MXene) epitaxial thin film2018In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 8, no 64, p. 36785-36790Article in journal (Refereed)
    Abstract [en]

    We investigate, and quantify, changes in structure and surface terminations of epitaxial thin films of titanium carbide (Ti3C2) MXene, when treated by sodium hydroxide solution followed by vacuum annealing at 550 degrees C. Using X-ray photoelectron spectroscopy and scanning transmission electron microscopy, we show that NaOH treatment produce an increase in the c-lattice parameter together with an increase in the O terminations and a decrease in the F terminations. There is also an increase in the percentage of the binding energy of Ti-species in Ti 2p XPS region, which suggests an increase in the overall oxidation state of Ti. After subsequent annealing, the c-lattice parameter is slightly reduced, the overall oxidation state of Ti is decreased, and the F surface terminations are further diminished, leaving a surface with predominantly O as the surface terminating species. It is important to note that NaOH treatment facilitates removal of F at lower annealing temperatures than previously reported, which in turn is important for the range of attainable properties.

  • 28.
    Halim, Joseph
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Palisaitis, Justinas
    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.
    Thörnberg, Jimmy
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    E. J., Moon
    Department of Materials Science and Engineering, Drexel University, Philadelphia, Pennsylvania 19104, United States.
    M., Precner
    Institute of Electrical Engineering, Slovak Academy of Sciences, Bratislava 84104, Slovak Republic.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Persson, Per O. Å.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    M. W., Barsoum
    Department of Materials Science and Engineering, Drexel University, Philadelphia, Pennsylvania 19104, United States.
    Rosén, Johanna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Synthesis of Two-Dimensional Nb1.33C (MXene) with Randomly Distributed Vacancies by Etching of the Quaternary Solid Solution (Nb2/3Sc1/3)2AlC MAX Phase2018In: ACS Applied Nano Materials, ISSN 2574-0970, Vol. 1, no 6, p. 2455-2460Article in journal (Refereed)
    Abstract [en]

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

  • 29.
    Gharavi, Mohammad Amin
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Armiento, Rickard
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Alling, Björn
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering. Max Planck Institute Eisenforsch GmbH, Germany.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Theoretical study of phase stability, crystal and electronic structure of MeMgN2 (Me = Ti, Zr, Hf) compounds2018In: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 53, no 6, p. 4294-4305Article in journal (Refereed)
    Abstract [en]

    Scandium nitride has recently gained interest as a prospective compound for thermoelectric applications due to its high Seebeck coefficient. However, ScN also has a relatively high thermal conductivity, which limits its thermoelectric efficiency and figure of merit (zT). These properties motivate a search for other semiconductor materials that share the electronic structure features of ScN, but which have a lower thermal conductivity. Thus, the focus of our study is to predict the existence and stability of such materials among inherently layered equivalent ternaries that incorporate heavier atoms for enhanced phonon scattering and to calculate their thermoelectric properties. Using density functional theory calculations, the phase stability of TiMgN2, ZrMgN2 and HfMgN2 compounds has been calculated. From the computationally predicted phase diagrams for these materials, we conclude that all three compounds are stable in these stoichiometries. The stable compounds may have one of two competing crystal structures: a monoclinic structure (LiUN2 prototype) or a trigonal superstructure (NaCrS2 prototype; RmH). The band structure for the two competing structures for each ternary is also calculated and predicts semiconducting behavior for all three compounds in the NaCrS2 crystal structure with an indirect band gap and semiconducting behavior for ZrMgN2 and HfMgN2 in the monoclinic crystal structure with a direct band gap. Seebeck coefficient and power factors are also predicted, showing that all three compounds in both the NaCrS2 and the LiUN2 structures have large Seebeck coefficients. The predicted stability of these compounds suggests that they can be synthesized by, e.g., physical vapor deposition.

  • 30.
    Halim, Joseph
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Moon, Eun Ju
    Drexel Univ, PA 19104 USA.
    Eklund, Per
    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.
    Barsoum, Michel W.
    Drexel Univ, PA 19104 USA.
    Ouisse, Thierry
    Univ Grenoble Alpes, France.
    Variable range hopping and thermally activated transport in molybdenum-based MXenes2018In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 98, no 10, article id 104202Article in journal (Refereed)
    Abstract [en]

    The magnetotransport of freestanding, vacuum filtered, thin films of Mo2CTz, Mo1.33CTz, Mo2TiC2Tz, and Mo2Ti2C3Tz was measured in the 10-300-K temperature (T) range. Some of the films were annealed before measuring their transport properties. Analysis of the results suggest that-with the exception of the heavily defective Mo1.33CTz composition-in the 10- to 200-K temperature regime, variable range hopping between individual MXene sheets is the operative conduction mechanism. For Mo1.33CTz it is more likely that variable range hopping within individual flakes is rate limiting. At higher temperatures, a thermally activated process emerges in all cases. It follows that improved fabrication processes should lead to considerable improvements in the electrical transport of Mo-based MXenes.

  • 31.
    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.

    The full text will be freely available from 2019-10-05 10:23
  • 32.
    Zhirkov, Igor
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Landälv, Ludvig
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. Sandvik Coromant, Sweden.
    Gothelid, E.
    Sandvik Coromant, Sweden.
    Ahlgren, M.
    Sandvik Coromant, Sweden.
    Eklund, Per
    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.
    Effect of Si on DC arc plasma generation from Al-Cr and Al-Cr-Si cathodes used in oxygen2017In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 121, no 8, article id 083303Article in journal (Refereed)
    Abstract [en]

    Al2O3 alloyed with Cr is an important material for the tooling industry. It can be synthesized from an arc discharge using Al-Cr cathodes in an oxygen atmosphere. Due to formation of Al-rich oxide islands on the cathode surface, the arc process stability is highly sensitive to oxygen pressure. For improved stability, the use of Al0.70Cr0.25Si0.05 cathodes has previously been suggested, where Si may reduce island formation. Here, we have investigated the effect of Si by comparing plasma generation and thin film deposition from Al0.7Cr0.3 and Al0.7Cr0.25Si0.05 cathodes. Plasma ion composition, ion energies, ion charge states, neutral species, droplet formation, and film composition have been characterized at different O-2 flow rates for arc currents of 60 and 90 A. Si and related compounds are detected in plasma ions and in plasma neutrals. Scanning electron microscopy and energy dispersive X-ray analysis show that the cathode composition and the film composition are the same, with Si present in droplets as well. The effect of Si on the process stability, ion energies, and ion charge states is found to be negligible compared to that of the arc current. The latter is identified as the most relevant parameter for tuning the properties of the reactive discharge. The present work increases the fundamental understanding of plasma generation in a reactive atmosphere, and provides input for the choice of cathode composition and process parameters in reactive DC arc synthesis.

  • 33.
    Eklund, Per
    et al.
    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.
    Persson, Per O A
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Layered ternary M(n+1)AX(n) phases and their 2D derivative MXene: an overview from a thin-film perspective2017In: Journal of Physics D: Applied Physics, ISSN 0022-3727, E-ISSN 1361-6463, Vol. 50, no 11, article id 113001Article, review/survey (Refereed)
    Abstract [en]

    Inherently and artificially layered materials are commonly investigated both for fundamental scientific purposes and for technological application. When a layered material is thinned or delaminated to its physical limits, a two-dimensional (2D) material is formed and exhibits novel properties compared to its bulk parent phase. The complex layered phases known as MAX phases (where M = early transition metal, A = A-group element, e.g. Al or Si, and X = C or N) are an exciting model system for materials design and the understanding of process-structure-property relationships. When the A layers are selectively etched from the MAX phases, a new type of 2D material is formed, named MXene to emphasize the relation to the MAX phases and the parallel with graphene. Since their discovery in 2011, MXenes have rapidly become established as a novel class of 2D materials with remarkable possibilities for composition variations and property tuning. This article gives a brief overview of MAX phases and MXene from a thin-film perspective, reviewing theory, characterization by electron microscopy, properties and how these are affected by the change in dimensionality, and outstanding challenges.

  • 34.
    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.

  • 35.
    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.

    The full text will be freely available from 2019-09-18 10:06
  • 36.
    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.

  • 37.
    Lai, Chung-Chuan
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Fashandi, Hossein
    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.
    Palisaitis, Justinas
    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.
    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.
    Rosén, Johanna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Phase formation of nanolaminated Mo2AuC and Mo-2(Au1-xGax)(2)C by a substitutional reaction within Au-capped Mo2GaC and Mo2Ga2C thin films2017In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 9, no 45, p. 17681-17687Article in journal (Refereed)
    Abstract [en]

    Au-containing nanolaminated carbides Mo2AuC and Mo-2(Au1-xGax)(2)C were synthesized by a thermally induced substitutional reaction in Mo2GaC and Mo2Ga2C, respectively. The Au substitution of the Ga layers in the structures was observed using cross-sectional high-resolution scanning transmission electron microscopy. Expansion of c lattice parameters was also observed in the Au-containing phases compared to the original phases. Energy dispersive spectroscopy detected residual Ga in Au-substituted layers of both phases with a peculiar Ga in-plane ordering for Au : Ga = 9 : 1 ratio along the Au-Ga layers in Mo-2(Au1-xGax)(2)C. These results indicate a generalization of the Au substitution reaction for the A elements in MAX phases.

  • 38.
    Kerdsongpanya, Sit
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. Rensselaer Polytech Institute, NY 12180 USA.
    Hellman, Olle
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering. CALTECH, CA 91125 USA.
    Sun, Bo
    National University of Singapore, Singapore.
    Kan Koh, Yee
    National University of Singapore, Singapore.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Van Nong, Ngo
    Department of Energy Conversion and Storage, Technical University of Denmark, Risø Campus, Roskilde, Denmark.
    Simak, Sergei I.
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering.
    Alling, Björn
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering. Max Planck Institute Eisenforsch GmbH, Germany.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Phonon thermal conductivity of scandium nitride for thermoelectrics from first-principles calculations and thin-film growth2017In: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 96, no 19, article id 195417Article in journal (Refereed)
    Abstract [en]

    The knowledge of lattice thermal conductivity of materials under realistic conditions is vitally important since many modern technologies require either high or low thermal conductivity. Here, we propose a theoretical model for determining lattice thermal conductivity, which takes into account the effect of microstructure. It is based on ab initio description that includes the temperature dependence of the interatomic force constants and treats anharmonic lattice vibrations. We choose ScN as a model system, comparing the computational predictions to the experimental data by time-domain thermoreflectance. Our experimental results show a trend of reduction in lattice thermal conductivity with decreasing domain size predicted by the theoretical model. These results suggest a possibility to control thermal conductivity by microstructural tailoring and provide a predictive tool for the effect of the microstructure on the lattice thermal conductivity of materials based on ab initio calculations.

  • 39.
    Tureson, Nina
    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, Roskilde, Denmark.
    Fournier, Daniele
    Sorbonne Universites, Paris, France.
    Singh, Niraj
    Indian Institute Technology Mandi, India.
    Acharya, Somnath
    Indian Institute Technology Mandi, India.
    Schmidt, Susann
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering. Ionbond Switzerland Olten, Switzerland.
    Belliard, Laurent
    University of Paris 06, France.
    Soni, Ajay
    Indian Institute Technology Mandi, India.
    Le Febvrier, Arnaud
    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.
    Reduction of the thermal conductivity of the thermoelectric material ScN by Nb alloying2017In: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 122, no 2, article id 025116Article in journal (Refereed)
    Abstract [en]

    ScN-rich (Sc,Nb)N solid solution thin films have been studied, motivated by the promising thermoelectric properties of ScN-based materials. Cubic Sc1-xNbxN films for 0 amp;lt;= x amp;lt;= 0.25 were epitaxially grown by DC reactive magnetron sputtering on a c-plane sapphire substrate and oriented along the (111) orientation. The crystal structure, morphology, thermal conductivity, and thermoelectric and electrical properties were investigated. The ScN reference film exhibited a Seebeck coefficient of -45 mu V/K and a power factor of 6 x 10(-4) W/m K-2 at 750K. Estimated from room temperature Hall measurements, all samples exhibit a high carrier density of the order of 10(21) cm(-3). Inclusion of heavy transition metals into ScN enables the reduction in thermal conductivity by an increase in phonon scattering. The Nb inserted ScN thin films exhibited a thermal conductivity lower than the value of the ScN reference (10.5W m(-1) K-1) down to a minimum value of 2.2 Wm(-1) K-1. Insertion of Nb into ScN thus resulted in a reduction in thermal conductivity by a factor of similar to 5 due to the mass contrast in ScN, which increases the phonon scattering in the material. Published by AIP Publishing.

  • 40.
    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.

  • 41.
    Landälv, Ludvig
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering. Sandvik Coromant AB, Sweden.
    Lu, Jun
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Spitz, S.
    Karlsruhe Institute Technology, Germany.
    Leiste, H.
    Karlsruhe Institute Technology, Germany.
    Ulrich, S.
    Karlsruhe Institute Technology, 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.
    Ahlgren, M.
    Sandvik Coromant AB, Sweden.
    Gothelid, E.
    Sandvik Coromant AB, Sweden.
    Alling, Björn
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical Physics. Linköping University, Faculty of Science & Engineering. Max Planck Institute Eisenforsch GmbH, Germany.
    Hultman, Lars
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Stueber, M.
    Karlsruhe Institute Technology, Germany.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Structural evolution in reactive RF magnetron sputtered (Cr,Zr)2O3 coatings during annealing2017In: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 131, p. 543-552Article in journal (Refereed)
    Abstract [en]

    Reactive RF-magnetron sputtering is used to grow Cr0.28Zr0.10O0.61 coatings at 500 degrees C. Coatings are annealed at 750 degrees C, 810 degrees C, and 870 degrees C. The microstructure evolution of the pseudobinary oxide compound is characterized through high resolution state of the art HRSTEM and HREDX-maps, revealing the segregation of Cr and Zr on the nm scale. The as-deposited coating comprises cc-(Cr,Zr)(2)O-3 solid solution with a Zr-rich (Zr,Cr)O-x. amorphous phase. After annealing to 750 degrees C tetragonal ZrO2 nucleates and grows from the amorphous phase. The ZrO2 phase is stabilized in its tetragonal structure at these fairly low annealing temperatures, possibly due to the small grain size (below 30 nm). Correlated with the nucleation and growth of the tetragonal-ZrO2 phase is an increase in hardness, with a maximum hardness after annealing to 750 degrees C, followed by a decrease in hardness upon coarsening, bcc metallic Cr phase formation and loss of oxygen, during annealing to 870 degrees C. The observed phase segregation opens up future design routes for pseudobinary oxides with tunable microstructural and mechanical properties. (C) 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  • 42.
    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.

  • 43.
    Ali, Sharafat
    et al.
    Linnaeus University, Sweden; Corning Inc, NY 14831 USA.
    Paul, Biplab
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Magnusson, Roger
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Broitman, Esteban
    Linköping University, Department of Physics, Chemistry and Biology. Linköping University, Faculty of Science & Engineering.
    Jonson, Bo
    Linnaeus University, Sweden.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Birch, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Synthesis and characterization of the mechanical and optical properties of Ca-Si-O-N thin films deposited by RF magnetron sputtering2017In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 315, p. 88-94Article in journal (Refereed)
    Abstract [en]

    Ca-Si-O-N thin films were deposited on commercial soda-lime silicate float glass, silica wafers and sapphire substrates by RF magnetron co-sputtering from Ca and Si targets in an Ar/N-2/O-2 gas mixture. Chemical composition, surface morphology, hardness, reduced elastic modulus and optical properties of the films were investigated using X-ray photoelectron spectroscopy, scanning electron microscopy, nanoindentation, and spectroscopic ellipsometry. It was found that the composition of the films can be controlled by the Ca target power, predominantly, and by the reactive gas flow. Thin films in the Ca-Si-O-N system are composed of N and Ca contents up to 31 eq. % and 60 eq. %, respectively. The films thickness ranges from 600 to 3000 nm and increases with increasing Ca target power. The films surface roughness varied between 2 and 12 nm, and approximately decreases with increasing power of Ca target. The hardness (4-12 GPa) and reduced elastic modulus (65-145 GPa) of the films increase and decrease with the N and Ca contents respectively. The refractive index (1.56-1.82) is primarily dictated by the N content. The properties are compared with findings for bulk glasses in the Ca-Si-(Al)-O-N systems, and it is concluded that Ca-Si-O-N thin films have higher values of hardness, elastic modulus and refractive index than bulk glasses of similar composition. (C) 2017 Elsevier B.V. All rights reserved.

  • 44.
    Zhou, Jie
    et al.
    Chinese Academic Science, Peoples R China; University of Chinese Academic Science, Peoples R China.
    Zha, Xianhu
    Chinese Academic Science, Peoples R China.
    Zhou, Xiaobing
    Chinese Academic Science, Peoples R China.
    Chen, Fanyan
    Chinese Academic Science, Peoples R China.
    Gao, Guoliang
    Chinese Academic Science, Peoples R China.
    Wang, Shuwei
    Chinese Academic Science, Peoples R China.
    Shen, Cai
    Chinese Academic Science, Peoples R China.
    Chen, Tao
    Chinese Academic Science, Peoples R China.
    Zhi, Chunyi
    City University of Hong Kong, Peoples R China.
    Eklund, Per
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Du, Shiyu
    Chinese Academic Science, Peoples R China.
    Xue, Jianming
    Peking University, Peoples R China.
    Shi, Weiqun
    Chinese Academic Science, Peoples R China; Chinese Academic Science, Peoples R China.
    Chai, Zhifang
    Chinese Academic Science, Peoples R China; Chinese Academic Science, Peoples R China.
    Huang, Qing
    Chinese Academic Science, Peoples R China.
    Synthesis and Electrochemical Properties of Two-Dimensional Hafnium Carbide2017In: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 11, no 4, p. 3841-3850Article in journal (Refereed)
    Abstract [en]

    We demonstrate fabrication of a two-dimensional Hf-containing MXene, Hf3C2Tz, by selective etching of a layered parent Hf-3[Al(Si)](4)C-6 compound. A substitutional solution of Si on Al sites effectively weakened the interfacial adhesion between Hf-C and Al(Si)-C sublayers within the unit cell of the parent compound, facilitating the subsequent selective etching. The underlying mechanism of the Si-alloying-facilitated etching process is thoroughly studied by first-principles density functional calculations. The result showed that more valence electrons of Si than Al weaken the adhesive energy of the etching interface. The MXenes were determined to be flexible and conductive. Moreover, this 2D Hf-containing MXene material showed reversible volumetric capacities of 1567 and 504 mAh cm(-3) for lithium and sodium ions batteries, respectively, at a current density of 200 mAg(-1) after 200 cycles. Thus, Hf3C2Tz MXenes with a 2D structure are candidate anode materials for metal-ion intercalation, especially for applications where size matters.

  • 45.
    Fashandi, Hossein
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Dahlqvist, Martin
    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.
    Palisaitis, Justinas
    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.
    Abrikosov, Igor
    Linköping University, Department of Physics, Chemistry and Biology, Theoretical 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.
    Andersson, Mike
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. 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.
    Synthesis of Ti3AuC2, Ti3Au2C2 and Ti3IrC2 by noble metal substitution reaction in Ti3SiC2 for high-temperature-stable Ohmic contacts to SiC2017In: Nature Materials, ISSN 1476-1122, E-ISSN 1476-4660, Vol. 16, no 8, p. 814-818Article in journal (Refereed)
    Abstract [en]

    The large class of layered ceramics encompasses both van der Waals (vdW) and non-vdW solids. While intercalation of noble metals in vdW solids is known, formation of compounds by incorporation of noble-metal layers in non-vdW layered solids is largely unexplored. Here, we show formation of Ti3AuC2 and Ti3Au2C2 phases with up to 31% lattice swelling by a substitutional solid-state reaction of Au into Ti3SiC2 single-crystal thin films with simultaneous out-diffusion of Si. Ti3IrC2 is subsequently produced by a substitution reaction of Ir for Au in Ti3Au2C2. These phases form Ohmic electrical contacts to SiC and remain stable after 1,000 h of ageing at 600 degrees C in air. The present results, by combined analytical electron microscopy and ab initio calculations, open avenues for processing of noble-metal-containing layered ceramics that have not been synthesized from elemental sources, along with tunable properties such as stable electrical contacts for high-temperature power electronics or gas sensors.

  • 46.
    Lai, Chung-Chuan
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Petruhins, Andrejs
    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.
    Farle, Michael
    Univ Duisburg Essen, Germany; Univ Duisburg Essen, Germany; Immanuel Kant Baltic Fed Univ, Russia.
    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.
    Rosén, Johanna
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Thermally induced substitutional reaction of Fe into Mo2GaC thin films2017In: MATERIALS RESEARCH LETTERS, ISSN 2166-3831, Vol. 5, no 8, p. 533-539Article in journal (Refereed)
    Abstract [en]

    The first Fe-based MAX phase is realized by solid-state substitution reaction of an Fe/Au/Mo2GaC thin-film diffusion couple, as determined by X-ray diffraction and scanning transmission electron microscopy. Chemical analysis together with elemental mapping reveals that as much as 50 at.% Fe on the A site can be obtained by thermally induced Au and Fe substitution for Ga atomic layers in Mo2GaC. One-sixth of the original Ga is also replaced by Au atoms. When annealing Mo2GaC thin films covered with Fe only, the Mo2GaC phase remains intact, that is, Au acts as a catalyst for the substitution reaction. [GRAPHICS] .

  • 47.
    Fashandi, Hossein
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Lai, Chung-Chuan
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Dahlqvist, Martin
    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.
    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.
    Greczynski, Grzegorz
    Linköping University, Department of Physics, Chemistry and Biology, Thin Film Physics. Linköping University, Faculty of Science & Engineering.
    Andersson, Mike
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. 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.
    Ti2Au2C and Ti3Au2C2 formed by solid state reaction of gold with Ti2AlC and Ti3AlC22017In: Chemical Communications, ISSN 1359-7345, E-ISSN 1364-548X, Vol. 53, no 69, p. 9554-9557Article in journal (Refereed)
    Abstract [en]

    Incorporation of layers of noble metals in non-van der Waals layered materials may be used to form novel layered compounds. Recently, we demonstrated a high-temperature-induced exchange process of Au with Si in the layered phase Ti3SiC2, resulting in the formation of Ti3AuC2 and Ti3Au2C2. Here, we generalize this technique showing that Au/Ti2AlC and Au/Ti3AlC2 undergo an exchange reaction at 650 [degree]C to form Ti2Au2C and Ti3Au2C2 and determine their structures by electron microscopy, X-ray diffraction, and ab initio calculations. These results imply that noble-metal-containing layered phases should be possible to synthesize in many systems. The metal to be introduced should be inert to the transition-metal carbide layers, and exhibit negative heat of mixing with the initial A element in a liquid phase or two-phase liquid/solid region at the annealing temperature.

  • 48.
    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.

  • 49.
    Zhou, Jie
    et al.
    Chinese Academic Science, Peoples R China.
    Zha, Xianhu
    Chinese Academic Science, Peoples R China.
    Chen, Fan Y.
    Chinese Academic Science, Peoples R China.
    Ye, Qun
    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.
    Du, Shiyu
    Chinese Academic Science, Peoples R China.
    Huang, Qing
    Chinese Academic Science, Peoples R China.
    A Two-Dimensional Zirconium Carbide by Selective Etching of Al3C3 from Nanolaminated Zr3Al3C52016In: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 55, no 16, p. 5008-5013Article in journal (Refereed)
    Abstract [en]

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

  • 50.
    Fashandi, Hossein
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Soldemo, Markus
    KTH Royal Institute Technology, Sweden.
    Weissenrieder, Jonas
    KTH Royal Institute Technology, Sweden.
    Gothelid, Mats
    KTH Royal Institute Technology, Sweden.
    Eriksson, Jens
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. 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.
    Lloyd Spetz, Anita
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Andersson, Mike
    Linköping University, Department of Physics, Chemistry and Biology, Applied Sensor Science. Linköping University, Faculty of Science & Engineering.
    Applicability of MOS structures in monitoring catalytic properties, as exemplified for monolayer-iron-oxide-coated porous platinum films2016In: Journal of Catalysis, ISSN 0021-9517, E-ISSN 1090-2694, Vol. 344, p. 583-590Article in journal (Refereed)
    Abstract [en]

    Metal Oxide Semiconductor (MOS) capacitor devices comprised of monolayer iron oxide-coated as well as non-coated polycrystalline Pt deposited on oxidized silicon carbide substrates have been fabricated and their usefulness as realistic model systems in catalyst studies development was evaluated. The CO oxidation characteristics of both iron oxide- and non-coated Pt catalysts were investigated using mass spectrometry, monitoring the carbon dioxide production rate for different combinations of carbon monoxide (CO) and oxygen concentrations at various temperatures. Additionally, the output capacitance of the MOS model catalysts was recorded for each individual CO oxidation activity. A low-temperature shift in CO oxidation characteristics for the monolayer-coated compared to the non-coated Pt catalysts was observed, similar to that previously reported for monolayer iron oxide grown on single-crystalline Pt substrates. A strong correlation between the output capacitance of the MOS structures and the CO oxidation characteristics was found for both monolayer- and non-coated model catalysts. Furthermore, the devices exhibit retained MOS electrical output and CO oxidation characteristics as well as an unaffected catalyst surface composition, as confirmed by photoelectron spectroscopy, even after 200 h of continuous model catalyst operation. In addition to the implications on practical applicability of monolayer iron oxide coating on widely used polycrystalline Pt films in real-world catalysts and sensors, the findings also point to new possibilities regarding the use of MOS model systems for in situ characterization, high throughput screening, and tailoring of e.g. catalyst- and fuel-cell-electrode materials for specific applications. (C) 2016 Elsevier Inc. All rights reserved.

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