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  • 1.
    Casillas-Trujillo, Luis
    et al.
    Linköping Univ, Dept Phys Chem & Biol IFM, SE-58183 Linköping, Sweden..
    Osinger, Barbara
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Lindblad, Rebecka
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Karlsson, Dennis
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Abrikosov, Alexei I.
    Linköping Univ, Dept Sci & Technol, SE-58183 Norrköping, Sweden..
    Fritze, Stefan
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    von Fieandt, Kristina
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Alling, Björn
    Linköping Univ, Dept Phys Chem & Biol IFM, SE-58183 Linköping, Sweden..
    Hotz, Ingrid
    Linköping Univ, Dept Sci & Technol, SE-58183 Norrköping, Sweden..
    Jansson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Abrikosov, Igor A.
    Linköping Univ, Dept Phys Chem & Biol IFM, SE-58183 Linköping, Sweden.;Natl Univ Sci & Technol MISIS, Mat Modelling & Dev Lab, Moscow 119049, Russia..
    Lewin, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Experimental and theoretical evidence of charge transfer in multi-component alloys: how chemical interactions reduce atomic size mismatch2021In: Materials Chemistry Frontiers, E-ISSN 2052-1537, Vol. 5, no 15, p. 5746-5759Article in journal (Refereed)
    Abstract [en]

    Ab initio simulations of a multi-component alloy using density functional theory (DFT) were combined with experiments on thin films of the same material using X-ray photoelectron spectroscopy (XPS) to study the connection between the electronic and atomic structures of multi-component alloys. The DFT simulations were performed on an equimolar HfNbTiVZr multi-component alloy. Structure and charge transfer were evaluated using relaxed, non-relaxed, as well as elemental reference structures. The use of a fixed sphere size model allowed quantification of charge transfer, and separation into different contributions. The charge transfer was generally found to follow electronegativity trends and results in a reduced size mismatch between the elements, and thus causes a considerable reduction of the lattice distortions compared to a traditional assumption based on tabulated atomic radii. A calculation of the average deviation from the average radius (i.e. the so-called δ-parameter) based on the atomic Voronoi volumes gave a reduction of δ from ca. 6% (using the volumes in elemental reference phases) to ca. 2% (using the volumes in the relaxed multi-component alloy phase). The reliability of the theoretical results was confirmed by XPS measurements of a Hf22Nb19Ti18V19Zr21 thin film deposited by sputter deposition. The experimentally observed core level binding energy shifts (CLS), as well as peak broadening due to a range of chemical surroundings, for each element showed good agreement with the calculated DFT values. The single solid solution phase of the sample was confirmed by X-ray diffraction (XRD) and transmission electron microscopy (TEM) including energy dispersive spectroscopy (EDS) with nm-resolution. These observations show that the HfNbTiVZr solid solution phase is non-ideal, and that chemical bonding plays an important part in the structure formation, and presumably also in the properties. Our conclusions should be transferable to other multi-component alloy systems, as well as some other multi-component material systems, and open up interesting possibilities for the design of material properties via the electronic structure and controlled charge transfer between selected metallic elements in the materials.

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  • 2.
    Fritze, Stefan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Chen, M.
    Swiss Fed Inst Technol, Lab Nanomet, Vladimir Prelog Weg 5, CH-8093 Zurich, Switzerland..
    Riekehr, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Osinger, Barbara
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Sortica, Mauricio A.
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory.
    Srinath, Aishwarya
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Menon, Ashok S.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Lewin, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Primetzhofer, Daniel
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Wheeler, J. M.
    Swiss Fed Inst Technol, Lab Nanomet, Vladimir Prelog Weg 5, CH-8093 Zurich, Switzerland..
    Jansson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Magnetron sputtering of carbon supersaturated tungsten films-A chemical approach to increase strength2021In: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 208, article id 109874Article in journal (Refereed)
    Abstract [en]

    Tungsten (W)-based materials attract significant attention due to their superior mechanical properties. Here, we present a chemical approach based on the addition of carbon (C) for increased strength via the combination of three strengthening mechanisms in W thin films. W:C thin films with C concentrations up to-4 at.% were deposited by magnetron sputtering. All films exhibit a body-centred-cubic structure with strong texture and columnar growth behaviour. X-ray and electron diffraction measurements suggest the formation of supersaturated W:C solid solution phases. The addition of C reduced the average column width from-133 nm for W to-20 nm for the film containing-4 at.% C. The column refinement is explained by a mechanism where C acts as re-nucleation sites. The W film is-13 GPa hard, while the W:C films achieve a peak hardness of-24 GPa. The W:C films are-11 GPa harder than the W film, which is explained by a combination of grain refinement strengthening, solid solution strengthening and increased dislocation density. Additional micropillar compression tests showed that the flow stress increased upon C addition, from-3.8 to-8.3 GPa and no brittle fracture was observed.

  • 3.
    Fritze, Stefan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Hahn, R.
    Institute of Materials Science and Technology, TU Wien, Vienna, Austria.
    Aboulfadl, H.
    Department of Physics, Chalmers University of Technology, Göteborg, Sweden.
    Johansson, Fredrik O.L.
    Division of Applied Physical Chemistry, Department of Chemistry, KTH – Royal Institute of Technology, SE-100 44 Stockholm, Sweden; Institute Methods and Instrumentation for Synchrotron Radiation Research PS-ISRR, Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Straße 15, 12489 Berlin, Germany; Institut für Physik und Astronomie, Universität Potsdam, Karl-Liebknecht-Strasse 24-25, 14476 Potsdam, Germany.
    Lindblad, Rebecka
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström.
    Böör, Katalin
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Lindblad, Andreas
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Berggren, Elin
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Condensed Matter Physics of Energy Materials.
    Kühn, D.
    Institute Methods and Instrumentation for Synchrotron Radiation Research PS-ISRR, Helmholtz-Zentrum Berlin für Materialien und Energie, Berlin, Germany.
    Leitner, T.
    Institute Methods and Instrumentation for Synchrotron Radiation Research PS-ISRR, Helmholtz-Zentrum Berlin für Materialien und Energie, Berlin, Germany.
    Osinger, Barbara
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Lewin, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Jansson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Mayrhofer, P.H.
    Institute of Materials Science and Technology, TU Wien, Vienna, Austria.
    Thuvander, M.
    Department of Physics, Chalmers University of Technology, Göteborg, Sweden.
    Elemental distribution and fracture properties of magnetron sputtered carbon supersaturated tungsten films2024In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 477, article id 130326Article in journal (Refereed)
    Abstract [en]

    The combination of strength and toughness is a major driving force for alloy design of protective coatings, and nanocrystalline tungsten (W)-alloys have shown to be promising candidates for combining strength and toughness. Here we investigate the elemental distribution and the fracture toughness of carbon (C) alloyed W thin films prepared by non-reactive magnetron sputtering. W:C films with up to ~4 at.% C crystallize in a body-centered-cubic structure with a strong 〈hh0〉texture, and no additional carbide phases are observed in the diffraction pattern. Atom probe tomography and X-ray photoelectron spectroscopy confirmed the formation of such a supersaturated solid solution. The pure W film has a hardness ~13 GPa and the W:C films exhibit a peak hardness of ~24 GPa. In-situ micromechanical cantilever bending tests show that the fracture toughness decreases from ~4.5 MPa·m1/2 for the W film to ~3.1 MPa·m1/2 for W:C films. The results show that C can significantly enhance the hardness of W thin films while retaining a high fracture toughness.

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  • 4.
    Fritze, Stefan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Hans, M.
    Materials Chemistry, RWTH Aachen University, Aachen, Germany.
    Riekehr, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Osinger, Barbara
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Lewin, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Schneider, J.M.
    Materials Chemistry, RWTH Aachen University, Aachen, Germany.
    Jansson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Influence of Carbon on Microstructure and Mechanical Properties of Magnetron Sputtered TaW Coatings2020In: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 196, article id 109070Article in journal (Refereed)
    Abstract [en]

    (Ta,W) and (Ta,W):C films with-5 at.% C were deposited by non-reactive magnetron sputtering. They crystallised in a bcc structure with a columnar microstructure. The solid solubility of C in (Ta,W) alloys is very low, which suggests that the (Ta,W):C films are supersaturated with respect to carbon. This was confirmed by diffraction and atom probe tomography (APT) showing that carbon is in the as-deposited (Ta,W):C films homogeneously distributed in the structure without carbide formation or carbon segregation. Annealing at 900 degrees C for 2 h showed no significant column coarsening but an increased defect density at the column boundaries in the (Ta,W):C films. The films were still supersaturated with respect to carbon but APT showed a partial segregation of carbon presumably to defect-rich column boundaries after annealing. The (Ta,W) films exhibited a hardness of-12-13 GPa. Alloying with carbon increased the hardness to-17 GPa. The hardness increased to-19 GPa for the annealed (Ta,W):C films. This annealing-induced hardness increase was explained by C segregation to the more defect-rich column boundaries, which restricts dislocation movements. (Ta,W):C coatings may be a potential alternative to ceramic coatings, worth exploring further by small scale mechanical testing to investigate if these materials are ductile.

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  • 5. Mukhamedov, B.O.
    et al.
    Fritze, Stefan
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Ottosson, Mikael
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Osinger, Barbara
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Lewin, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Alling, B.
    Jansson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Abrikosov, I.A.
    Tetragonal distortion in magnetron sputtered bcc-W films with supersaturated carbon2022In: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 214, article id 110422Article in journal (Refereed)
    Abstract [en]

    Carbon has a low solid solubility in bcc tungsten at equilibrium. However, metastable supersaturated solid solutions can be synthesized with magnetron sputtering. Here, we present a systematic study on the phase stability and mechanical properties of such supersaturated W–C solid solutions. Θ–2θ scans show a split of the 200/020 and the 002 peaks for supersaturated films which is explained by a tetragonal distortion of the bcc structure. This split increases with increasing C content and is maximized at 4 at.% C, where we observe an a/b axis of 3.15–3.16 Å and a c-axis of 3.21–3.22 Å. We performed first-principles calculations of lattice parameters, mixing enthalpies, elastic constants and polycrystalline elastic moduli for cubic and tetragonal W–C solid solutions. Calculations show that tetragonal structure is more stable than the bcc supersaturated solid solution and the calculated lattice parameters and Young’s moduli follow the same trends as the experimental ones as a function of C concentration. The results suggest that supersaturated films with lattice distortion can be used as a design approach to improve the properties of transition metal films with a bcc structure.

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  • 6.
    Osinger, Barbara
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Investigation of compositionally complex refractory metal based thin films2024Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The search for new and improved materials has led to the discovery and establishment of compositionally complex or high-entropy materials. The work in this thesis is focused on the investigation of new compositionally complex materials based on the refractory metals of groups 4-6. The materials in this work were synthesised using non-reactive dc magnetron sputtering and three material systems have been studied: HfNbTiVZr-C, CrTiTaWNb-C and Nb-Mo-C. In the context of compositionally complex materials, this thesis aims to contribute specifically to questions regarding (i) the prediction of phase formation and stability (ii) the chemical interaction between atoms (iii) the correlation between the material properties and compositional complexity. 

    The prediction of phase formation and stability using calculated phase diagram (CALPHAD) methods was studied in the HfNbTiVZr-C system. The findings suggest that CALPHAD methods are promising predictive tools, although kinetic effects during synthesis need to be taken into consideration. Furthermore, theoretical, and experimental evidence of charge transfer effects was demonstrated within the HfNbTiVZr-C system. The results of ab initio materials simulations and X-ray Photoelectron Spectroscopy (XPS) measurements highlight the importance of understanding and considering the local chemical environment and chemical interactions in compositionally complex materials.

    The approach of metal alloying according to the valence electron concentration (VEC) to tune the mechanical properties was studied in the Nb-Mo-C system. The findings show the importance of microstructural effects on the mechanical properties in the studied thin film materials, which can overshadow the compositional or VEC variations. 

    The response to Xe heavy-ion irradiation was studied in the CrTiTaWNb-C system using in situ irradiation experiments. This work presents a comparison between three different compositions: a TaW-rich alloy and carbide thin film as well as a near-equimolar carbide film. The findings indicate that both microstructure and chemical homogeneity play important roles when it comes to radiation damage tolerance in compositional complex materials.

    This thesis demonstrates the elaborate and multifaceted nature of compositionally complex materials. Whether it comes to the fundamental understanding or the effective implementation of a materials design tool, many factors need to be taken into consideration, including chemical interactions between the constituent elements and microstructural effects.

    List of papers
    1. Investigation of the phase formation in magnetron sputtered hard multicomponent (HfNbTiVZr)C coatings
    Open this publication in new window or tab >>Investigation of the phase formation in magnetron sputtered hard multicomponent (HfNbTiVZr)C coatings
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    2022 (English)In: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 221, article id 111002Article in journal (Refereed) Published
    Abstract [en]

    Multicomponent carbides have gained interest especially for ultra-high temperature applications, due to their ceramic hardness, good oxidation resistance and enhanced strength. In this study the phase forma-tion, stability and mechanical properties of (HfNbTiVZr)C multicomponent carbide coatings were inves-tigated. Phase stability was predicted by the CALPHAD (CALculation of PHAse Diagrams) methods. This revealed that the multicomponent solid solution phase is only stable at elevated temperatures, namely above 2400 degrees C. At lower temperatures a phase mixture was predicted, with a particular tendency for V to segregate. Magnetron sputtered thin films deposited at 300 degrees C exhibited a single NaCl-type multicom-ponent carbide phase, which attributes to the kinetic stabilisation of simple structures during thin film growth. Films deposited at 700 degrees C, or exposed to UHV annealing at 1000 degrees C, however, revealed the decom-position of the single-phase multicomponent carbide by partial elemental segregation and formation of additional phases. Thus, confirming the CALPHAD predictions. These results underscore the importance of explicitly considering temperature when discussing the stability of multicomponent carbide materials, as well as the applicability of CALPHAD methods for predicting phase formation and driving forces in these materials. The latter being crucial for designing materials, such as carbides, that are used in appli-cations at elevated temperatures.

    Place, publisher, year, edition, pages
    ElsevierElsevier BV, 2022
    Keywords
    High entropy ceramics, Multi -principal element carbide, Multicomponent carbide, Physical vapour deposition (PVD), CALPHAD
    National Category
    Materials Chemistry
    Identifiers
    urn:nbn:se:uu:diva-482676 (URN)10.1016/j.matdes.2022.111002 (DOI)000839257000004 ()
    Funder
    Swedish Research Council, 2018-04834Swedish Research CouncilSwedish Research Council, 2017-00646_9Swedish Foundation for Strategic Research, RIF14-0053
    Available from: 2022-09-07 Created: 2022-09-07 Last updated: 2024-01-15Bibliographically approved
    2. Experimental and theoretical evidence of charge transfer in multi-component alloys: how chemical interactions reduce atomic size mismatch
    Open this publication in new window or tab >>Experimental and theoretical evidence of charge transfer in multi-component alloys: how chemical interactions reduce atomic size mismatch
    Show others...
    2021 (English)In: Materials Chemistry Frontiers, E-ISSN 2052-1537, Vol. 5, no 15, p. 5746-5759Article in journal (Refereed) Published
    Abstract [en]

    Ab initio simulations of a multi-component alloy using density functional theory (DFT) were combined with experiments on thin films of the same material using X-ray photoelectron spectroscopy (XPS) to study the connection between the electronic and atomic structures of multi-component alloys. The DFT simulations were performed on an equimolar HfNbTiVZr multi-component alloy. Structure and charge transfer were evaluated using relaxed, non-relaxed, as well as elemental reference structures. The use of a fixed sphere size model allowed quantification of charge transfer, and separation into different contributions. The charge transfer was generally found to follow electronegativity trends and results in a reduced size mismatch between the elements, and thus causes a considerable reduction of the lattice distortions compared to a traditional assumption based on tabulated atomic radii. A calculation of the average deviation from the average radius (i.e. the so-called δ-parameter) based on the atomic Voronoi volumes gave a reduction of δ from ca. 6% (using the volumes in elemental reference phases) to ca. 2% (using the volumes in the relaxed multi-component alloy phase). The reliability of the theoretical results was confirmed by XPS measurements of a Hf22Nb19Ti18V19Zr21 thin film deposited by sputter deposition. The experimentally observed core level binding energy shifts (CLS), as well as peak broadening due to a range of chemical surroundings, for each element showed good agreement with the calculated DFT values. The single solid solution phase of the sample was confirmed by X-ray diffraction (XRD) and transmission electron microscopy (TEM) including energy dispersive spectroscopy (EDS) with nm-resolution. These observations show that the HfNbTiVZr solid solution phase is non-ideal, and that chemical bonding plays an important part in the structure formation, and presumably also in the properties. Our conclusions should be transferable to other multi-component alloy systems, as well as some other multi-component material systems, and open up interesting possibilities for the design of material properties via the electronic structure and controlled charge transfer between selected metallic elements in the materials.

    Place, publisher, year, edition, pages
    Royal Society of ChemistryRoyal Society of Chemistry (RSC), 2021
    National Category
    Materials Chemistry Condensed Matter Physics
    Identifiers
    urn:nbn:se:uu:diva-468314 (URN)10.1039/d1qm00380a (DOI)000664149100001 ()
    Funder
    Swedish Research Council, 2018-04834Swedish Research Council, 2019-05403Swedish Research Council, 2018-05973Swedish Research Council, 2019-05487Knut and Alice Wallenberg Foundation, KAW-2018.0194Swedish Foundation for Strategic Research , FFL 15-0290Swedish National Infrastructure for Computing (SNIC)
    Available from: 2022-02-25 Created: 2022-02-25 Last updated: 2024-01-15Bibliographically approved
    3. Charge transfer effects in (HfNbTiVZr)C – shown by ab-initio calculations and X-ray photoelectron spectroscopy
    Open this publication in new window or tab >>Charge transfer effects in (HfNbTiVZr)C – shown by ab-initio calculations and X-ray photoelectron spectroscopy
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    (English)In: Article in journal (Other academic) Submitted
    Abstract [en]

    Considering charge transfer effects and the variability of the bonding between elements with different electronegativity opens up a deeper understanding of the electronic structure and as a result many of the properties in high entropy related materials. This study investigates the importance of the diverse bonding and chemical environments when discussing multicomponent carbide materials. A combination of ab initio calculations and X-ray photoelectron spectroscopy (XPS) was used to investigate the electronic structure of multicomponent thin films based on the (HfNbTiVZr)C system. The charge transfer was quantified theoretically using relaxed and non-relaxed multicomponent as well as binary carbide reference structures, employing a fixed sphere model. High-resolution XPS spectra from (HfNbTiVZr)C magnetron sputtered thin films displayed core level binding energy shifts and broadening effects as a result of the complex chemical environment. Charge transfer effects and a changed electronic structure in the multicomponent material, compared with the reference binary carbides, are observed both experimentally and in the DFT simulations. The observed effects loosely follow electronegativity considerations, leading to a deviation from an ideal solid solution structure assuming non-distinguishable chemically equivalent environments. 

    Keywords
    DFT, Magnetron sputtering, Multicomponent carbide, X-ray Photoelectron spectroscopy, Charge transfer
    National Category
    Materials Chemistry
    Research subject
    Chemistry with specialization in Materials Chemistry
    Identifiers
    urn:nbn:se:uu:diva-517270 (URN)
    Available from: 2024-01-09 Created: 2024-01-09 Last updated: 2024-01-19
    4. Structural and mechanical properties of magnetron sputtered (NbxMo1-x)C thin films
    Open this publication in new window or tab >>Structural and mechanical properties of magnetron sputtered (NbxMo1-x)C thin films
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    (English)In: Article in journal (Other academic) Submitted
    Abstract [en]

    While transition metal carbides (TMCs) exhibit favourable mechanical properties, alloying according to the valence electron concentration (VEC) has the potential to further enhance the properties of these hard but inherently brittle materials. This study investigates the influence of alloying on the microstructure and mechanical properties of (NbxMo1-x)C carbide films, including binary references and ternary compositions with varying metal ratios (x between 0.35 and 0.52). Furthermore, the influence of various substrate materials is studied by comparing films deposited on Al2O3, MgO and SiO2. All films exhibit a NaCl-type carbide structure and X-ray photoelectron spectroscopy revealed the presence of small amounts of an additional amorphous carbon (a-C) phase. Hardness values around 20 ± 2 GPa were obtained for the films on Al2O3 and MgO, whereas a reduced hardness of 11 ± 1 GPa was observed for the films on SiO2 which is attributed to larger crystallite size and more polycrystalline structure. Overall no clear trend as a function of composition can be noted, indicating that microstructure effects dominate the mechanical properties in this study overshadowing the effect of varying the metal content.

    Keywords
    Magnetron sputtering, Ceramic coating, Transition metal carbides, Mechanical properties
    National Category
    Materials Chemistry
    Research subject
    Chemistry with specialization in Materials Chemistry
    Identifiers
    urn:nbn:se:uu:diva-517298 (URN)
    Available from: 2024-01-09 Created: 2024-01-09 Last updated: 2024-01-12
    5. From high-entropy alloys to high-entropy ceramics: The radiation-resistant highly concentrated refractory carbide (CrNbTaTiW)C
    Open this publication in new window or tab >>From high-entropy alloys to high-entropy ceramics: The radiation-resistant highly concentrated refractory carbide (CrNbTaTiW)C
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    2023 (English)In: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 250, article id 118856Article in journal (Refereed) Published
    Abstract [en]

    High-entropy materials represent the state-of-the-art on the alloy design strategy for future applications in extreme environments. Recent data indicates that high-entropy alloys (HEAs) exhibit outstanding radiation resistance in face of existing diluted alloy counterparts due to suppressed damage formation and evolution. An extension of the HEA concept is presented in this paper towards the synthesis and characterization of novel high-entropy ceramics as emergent materials for application in environments where energetic particle irradiation is a major concern. A novel carbide within the quinary refractory system CrNbTaTiW has been synthesized using magnetron-sputtering. The material exhibited nanocrystalline grains, single-phase crystal structure and C content around 50 at.%. Heavy-ion irradiation with in-situ Transmission Electron Microscopy was used to assess the irradiation response of the new high-entropy carbide (HEC) at 573 K and a comparison with the HEA within the system is made. No displacement damage effects appear within the microstructures of both HEA and HEC up to a dose of 10 displacements-per-atom. Surprisingly, the HEC has not amorphized under the investigated conditions. Xe was implanted in both materials and bubbles nucleated, but smaller sizes compared with conventional nuclear materials shedding light they are potential candidates for use in nuclear energy.

    Place, publisher, year, edition, pages
    Elsevier, 2023
    Keywords
    High-entropy ceramics, High-entropy alloys, Nanocrystalline materials, Radiation damage, Extreme environments
    National Category
    Materials Engineering
    Identifiers
    urn:nbn:se:uu:diva-499313 (URN)10.1016/j.actamat.2023.118856 (DOI)000958714700001 ()
    Funder
    EU, European Research Council, 757961Swedish Research Council, 2017-00646_9Swedish Research Council, 2019_00191Swedish Foundation for Strategic Research, RIF14-0053
    Available from: 2023-03-27 Created: 2023-03-27 Last updated: 2024-01-11Bibliographically approved
    6. Probing the high entropy concept through the irradiation response of near-equimolar (CrTiTaWNb)C ceramic coatings
    Open this publication in new window or tab >>Probing the high entropy concept through the irradiation response of near-equimolar (CrTiTaWNb)C ceramic coatings
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    (English)Manuscript (preprint) (Other academic)
    Keywords
    High-entropy ceramics, Coatings, radiation damage, extreme environments
    National Category
    Materials Chemistry
    Research subject
    Chemistry with specialization in Materials Chemistry
    Identifiers
    urn:nbn:se:uu:diva-517271 (URN)
    Available from: 2024-01-07 Created: 2024-01-07 Last updated: 2024-01-11
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  • 7.
    Osinger, Barbara
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Casillas-Trujillo, Luis
    Lindblad, Rebecka
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy.
    Alling, Björn
    Olovsson, Weine
    Abrikosov, Igor A.
    Lewin, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Charge transfer effects in (HfNbTiVZr)C – shown by ab-initio calculations and X-ray photoelectron spectroscopyIn: Article in journal (Other academic)
    Abstract [en]

    Considering charge transfer effects and the variability of the bonding between elements with different electronegativity opens up a deeper understanding of the electronic structure and as a result many of the properties in high entropy related materials. This study investigates the importance of the diverse bonding and chemical environments when discussing multicomponent carbide materials. A combination of ab initio calculations and X-ray photoelectron spectroscopy (XPS) was used to investigate the electronic structure of multicomponent thin films based on the (HfNbTiVZr)C system. The charge transfer was quantified theoretically using relaxed and non-relaxed multicomponent as well as binary carbide reference structures, employing a fixed sphere model. High-resolution XPS spectra from (HfNbTiVZr)C magnetron sputtered thin films displayed core level binding energy shifts and broadening effects as a result of the complex chemical environment. Charge transfer effects and a changed electronic structure in the multicomponent material, compared with the reference binary carbides, are observed both experimentally and in the DFT simulations. The observed effects loosely follow electronegativity considerations, leading to a deviation from an ideal solid solution structure assuming non-distinguishable chemically equivalent environments. 

  • 8.
    Osinger, Barbara
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Donzel-Gargand, Olivier
    Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Materials Science and Engineering, Solar Cell Technology.
    Fritze, Stefan
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Jansson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Lewin, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Structural and mechanical properties of magnetron sputtered (NbxMo1-x)C thin filmsIn: Article in journal (Other academic)
    Abstract [en]

    While transition metal carbides (TMCs) exhibit favourable mechanical properties, alloying according to the valence electron concentration (VEC) has the potential to further enhance the properties of these hard but inherently brittle materials. This study investigates the influence of alloying on the microstructure and mechanical properties of (NbxMo1-x)C carbide films, including binary references and ternary compositions with varying metal ratios (x between 0.35 and 0.52). Furthermore, the influence of various substrate materials is studied by comparing films deposited on Al2O3, MgO and SiO2. All films exhibit a NaCl-type carbide structure and X-ray photoelectron spectroscopy revealed the presence of small amounts of an additional amorphous carbon (a-C) phase. Hardness values around 20 ± 2 GPa were obtained for the films on Al2O3 and MgO, whereas a reduced hardness of 11 ± 1 GPa was observed for the films on SiO2 which is attributed to larger crystallite size and more polycrystalline structure. Overall no clear trend as a function of composition can be noted, indicating that microstructure effects dominate the mechanical properties in this study overshadowing the effect of varying the metal content.

  • 9.
    Osinger, Barbara
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Mao, Huahai
    KTH Royal Inst Technol, Stockholm, Sweden.;Thermo Calc Software AB, Solna, Sweden..
    Fritze, Stefan
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Riekehr, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Jansson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Lewin, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Investigation of the phase formation in magnetron sputtered hard multicomponent (HfNbTiVZr)C coatings2022In: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 221, article id 111002Article in journal (Refereed)
    Abstract [en]

    Multicomponent carbides have gained interest especially for ultra-high temperature applications, due to their ceramic hardness, good oxidation resistance and enhanced strength. In this study the phase forma-tion, stability and mechanical properties of (HfNbTiVZr)C multicomponent carbide coatings were inves-tigated. Phase stability was predicted by the CALPHAD (CALculation of PHAse Diagrams) methods. This revealed that the multicomponent solid solution phase is only stable at elevated temperatures, namely above 2400 degrees C. At lower temperatures a phase mixture was predicted, with a particular tendency for V to segregate. Magnetron sputtered thin films deposited at 300 degrees C exhibited a single NaCl-type multicom-ponent carbide phase, which attributes to the kinetic stabilisation of simple structures during thin film growth. Films deposited at 700 degrees C, or exposed to UHV annealing at 1000 degrees C, however, revealed the decom-position of the single-phase multicomponent carbide by partial elemental segregation and formation of additional phases. Thus, confirming the CALPHAD predictions. These results underscore the importance of explicitly considering temperature when discussing the stability of multicomponent carbide materials, as well as the applicability of CALPHAD methods for predicting phase formation and driving forces in these materials. The latter being crucial for designing materials, such as carbides, that are used in appli-cations at elevated temperatures.

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  • 10.
    Osinger, Barbara
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Tunes, Matheus A.
    Chair of Non-Ferrous Metallurgy, Montanuniversität Leoben, 8700 Austria.
    Willenshofer, Patrick
    Chair of Non-Ferrous Metallurgy, Montanuniversität Leoben, 8700 Austria.
    Greaves, Graeme
    School of Computing and Engineering, University of Huddersfield, Huddersfield HD1 3DH, United Kingdom .
    Ström, Petter
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Malinovskis, Paulius
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry. Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics. School of Computing and Engineering, University of Huddersfield, Huddersfield HD1 3DH, United Kingdom .
    Vishnyakov, Vladimir M.
    Lewin, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Fritze, Stefan
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Probing the high entropy concept through the irradiation response of near-equimolar (CrTiTaWNb)C ceramic coatingsManuscript (preprint) (Other academic)
  • 11. Tunes, Matheus A.
    et al.
    Fritze, Stefan
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Osinger, Barbara
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Willenshofer, Patrick
    Alvarado, Andrew M.
    Martinez, Enrique
    Menon, Ashok S.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Structural Chemistry.
    Ström, Petter
    Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Applied Nuclear Physics.
    Greaves, Graeme
    Lewin, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Jansson, Ulf
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Pogatscher, Stefan
    Saleh, Tarik A.
    Vishnyakov, Vladimir M.
    El-Atwani, Osman
    From high-entropy alloys to high-entropy ceramics: The radiation-resistant highly concentrated refractory carbide (CrNbTaTiW)C2023In: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 250, article id 118856Article in journal (Refereed)
    Abstract [en]

    High-entropy materials represent the state-of-the-art on the alloy design strategy for future applications in extreme environments. Recent data indicates that high-entropy alloys (HEAs) exhibit outstanding radiation resistance in face of existing diluted alloy counterparts due to suppressed damage formation and evolution. An extension of the HEA concept is presented in this paper towards the synthesis and characterization of novel high-entropy ceramics as emergent materials for application in environments where energetic particle irradiation is a major concern. A novel carbide within the quinary refractory system CrNbTaTiW has been synthesized using magnetron-sputtering. The material exhibited nanocrystalline grains, single-phase crystal structure and C content around 50 at.%. Heavy-ion irradiation with in-situ Transmission Electron Microscopy was used to assess the irradiation response of the new high-entropy carbide (HEC) at 573 K and a comparison with the HEA within the system is made. No displacement damage effects appear within the microstructures of both HEA and HEC up to a dose of 10 displacements-per-atom. Surprisingly, the HEC has not amorphized under the investigated conditions. Xe was implanted in both materials and bubbles nucleated, but smaller sizes compared with conventional nuclear materials shedding light they are potential candidates for use in nuclear energy.

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  • 12.
    von Fieandt, Kristina
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Pilloud, David
    Univ Lorraine, Campus ARTEM, UMR 7198, CNRS,Inst Jean Lamour, FR-54011 Nancy, France..
    Fritze, Stefan
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Osinger, Barbara
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Pierson, Jean-Francois
    Univ Lorraine, Campus ARTEM, UMR 7198, CNRS,Inst Jean Lamour, FR-54011 Nancy, France..
    Lewin, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Optical and electrical properties of hard (Hf,Nb,Ti,V,Zr)N-x thin films2021In: Vacuum, ISSN 0042-207X, E-ISSN 1879-2715, Vol. 193, article id 110517Article in journal (Refereed)
    Abstract [en]

    (Hf,Nb,Ti,V,Zr)N-x coatings with nitrogen content between 0 and 49 at.% were deposited by sputter deposition, and thoroughly characterised. Nitrogen-free coatings were found to have a bcc structure, low hardness (8 GPa), and an electrical resistivity of 144 mu Omega cm. The nitride coatings (43-49 at.% N) had NaCl-type structure, consistent with a multi-component solid solution phase. Photoelectron core level binding energies indicate that the electronic structure of the multi-component nitride differs from that of the binary nitrides, probably a result of charge transfer between the metal atoms. The nitride coatings exhibited a dense microstructure and a hardness between 29 and 33 GPa, and electrical resistivities of 141-254 mu Omega cm. They also exhibited a minimum in the optical reflectance, similar to that of TiN, indicating plasmonic properties. The position of this minimum was found to be shifted to smaller wavelengths (272-339 nm) compared to a TiN reference (428 nm) and varied with nitrogen content. The tuneability of the optical properties, in combination with the potential to influence the electronic structure through charge transfer between metal atoms point to new interesting routes to design optical materials, and a new class of optical materials based on the concept of multi-component nitrides.

  • 13.
    von Fieandt, Kristina
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Riekehr, Lars
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Osinger, Barbara
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Fritze, Stefan
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Lewin, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Inorganic Chemistry.
    Influence of N content on structure and mechanical properties of multi-component Al-Cr-Nb-Y-Zr based thin films by reactive magnetron sputtering2020In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 389, article id 125614Article in journal (Refereed)
    Abstract [en]

    Al-Cr-Nb-Y-Zr-N films have been deposited with reactive dc magnetron sputtering at various N-2 flow ratios to achieve films with different nitrogen content, from purely metallic to fully nitrided films. The structure evolved from mainly amorphous with a minor crystalline intermetallic phase for the film without nitrogen, to nanocomposites with a cubic crystalline phase in an amorphous matrix for intermediate nitrogen content (15-41 at.% N), and at higher nitrogen content (46-51 at.% N) to crystalline solid solution nitrides with a NaCl-type structure. Partial elemental segregation on the nanoscale was found in all studied samples and the films exhibited different segregation behaviour depending on the nitrogen content, implying that the structural evolution on the nanoscale of films in this material system complex and highly composition-dependent. The hardness increased with increasing nitrogen content, reaching a maximum at about 30 GPa at for the nitride films with 50 at.% N. Deformation behaviour, studied by indentation measurements, of the nitride films was found to be ductile, where no sign of crack formation could be observed. This can be attributed to a metallic phase in the columnar boundaries caused by partial elemental segregation of mainly yttrium. Hence, films within in this material system, although the nanostructure is found to be relatively complex, show very promising mechanical properties and the structural complexity can be used as a guide for designing nitride materials that combine high hardness with ductility.

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