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  • 1.
    Abrikosov, Igor
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Knutsson, Axel
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Alling, Björn
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Tasnádi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Lind, Hans
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Phase Stability and Elasticity of TiAlN2011Ingår i: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 4, nr 9, s. 1599-1618Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We review results of recent combined theoretical and experimental studies of Ti1−xAlxN, an archetypical alloy system material for hard-coating applications. Theoretical simulations of lattice parameters, mixing enthalpies, and elastic properties are presented. Calculated phase diagrams at ambient pressure, as well as at pressure of 10 GPa, show a wide miscibility gap and broad region of compositions and temperatures where the spinodal decomposition takes place. The strong dependence of the elastic properties and sound wave anisotropy on the Al-content offers detailed understanding of the spinodal decomposition and age hardening in Ti1−xAlxN alloy films and multilayers. TiAlN/TiN multilayers can further improve the hardness and thermal stability compared to TiAlN since they offer means to influence the kinetics of the favorable spinodal decomposition and suppress the detrimental transformation to w-AlN. Here, we show that a 100 degree improvement in terms of w-AlN suppression can be achieved, which is of importance when the coating is used as a protective coating on metal cutting inserts.

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  • 2.
    Alling, Björn
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Steneget, Peter
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Tholander, Christopher
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Tasnádi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Petrov, Ivan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Greene, Joseph E
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Configurational disorder effects on adatom mobilities on Ti1-xAlxN(001) surfaces from first principles2012Ingår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 85, nr 24, s. 245422-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We use metastable NaCl-structure Ti0.5Al0.5N alloys to probe effects of configurational disorder on adatom surface diffusion dynamics which control phase stability and nanostructural evolution during film growth. First-principles calculations were employed to obtain energy potential maps of Ti and Al adsorption on an ordered TiN(001) reference surface and a disordered Ti0.5Al0.5N(001) solid-solution surface. The energetics of adatom migration on these surfaces are determined and compared to isolate effects of configurational disorder. The results show that alloy surface disorder dramatically reduces Ti adatom mobilities. Al adatoms, in sharp contrast, experience only small disorder-induced differences in migration dynamics.

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  • 3.
    Bock, Florian
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Tasnadi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Active learning with moment tensor potentials to predict material properties: Ti0.5Al0.5N at elevated temperature2024Ingår i: Journal of Vacuum Science & Technology. A. Vacuum, Surfaces, and Films, ISSN 0734-2101, E-ISSN 1520-8559, Vol. 42, nr 1, artikel-id 013412Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Transition metal nitride alloys possess exceptional properties, making them suitable for cutting applications due to their inherent hardness or as protective coatings due to corrosion resistance. However, the computational demands associated with predicting these properties using ab initio methods can often be prohibitively high at the conditions of their operation at cutting tools, that is, at high temperatures and stresses. Machine learning approaches have been introduced into the field of materials modeling to address the challenge. In this paper, we present an active learning workflow to model the properties of our benchmark alloy system cubic B1 Ti0.5Al0.5N at temperatures up to 1500 K. With a minimal requirement of prior knowledge about the alloy system for our workflow, we train a moment tensor potential (MTP) to accurately model the material's behavior over the entire temperature range and extract elastic and vibrational properties. The outstanding accuracy of MTPs with relatively little training data demonstrates that the presented approach is highly efficient and requires about two orders of magnitude less computational resources than state-of-the-art ab initio molecular dynamics.

  • 4.
    Bykov, M.
    et al.
    Univ Bayreuth, Germany.
    Bykova, E.
    Univ Bayreuth, Germany; DESY, Germany.
    Aprilis, G.
    Univ Bayreuth, Germany.
    Glazyrin, K.
    DESY, Germany.
    Koemets, E.
    Univ Bayreuth, Germany.
    Chuvashova, I
    Univ Bayreuth, Germany; Univ Bayreuth, Germany.
    Kupenko, I
    Univ Munster, Germany.
    McCammon, C.
    Univ Bayreuth, Germany.
    Mezouar, M.
    European Synchrotron Radiat Facil, France.
    Prakapenka, V
    Univ Chicago, IL 60437 USA.
    Liermann, H-P
    DESY, Germany.
    Tasnadi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten. Natl Univ Sci and Technol MISIS, Russia.
    Ponomareva, A. V
    Natl Univ Sci and Technol MISIS, Russia.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Dubrovinskaia, N.
    Univ Bayreuth, Germany.
    Dubrovinsky, L.
    Univ Bayreuth, Germany.
    Fe-N system at high pressure reveals a compound featuring polymeric nitrogen chains2018Ingår i: Nature Communications, E-ISSN 2041-1723, Vol. 9, artikel-id 2756Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Poly-nitrogen compounds have been considered as potential high energy density materials for a long time due to the large number of energetic N-N or N=N bonds. In most cases high nitrogen content and stability at ambient conditions are mutually exclusive, thereby making the synthesis of such materials challenging. One way to stabilize such compounds is the application of high pressure. Here, through a direct reaction between Fe and N-2 in a laser-heated diamond anvil cell, we synthesize three ironnitrogen compounds Fe3N2, FeN2 and FeN4. Their crystal structures are revealed by single-crystal synchrotron X-ray diffraction. Fe3N2, synthesized at 50 GPa, is isostructural to chromium carbide Cr3C2. FeN2 has a marcasite structure type and features covalently bonded dinitrogen units in its crystal structure. FeN4, synthesized at 106 GPa, features polymeric nitrogen chains of [N-4(2-)](n) units. Based on results of structural studies and theoretical analysis, [N-4(2-)](n) units in this compound reveal catena-poly[tetraz-1-ene-1,4-diyl] anions.

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  • 5.
    Bykov, Maxim
    et al.
    Univ Bayreuth, Germany.
    Bykova, Elena
    Deutsch Elektronen Synchrotron DESY, Germany.
    Koemets, Egor
    Univ Bayreuth, Germany.
    Fedotenko, Timofey
    Univ Bayreuth, Germany.
    Aprilis, Georgios
    Univ Bayreuth, Germany.
    Glazyrin, Konstantin
    Deutsch Elektronen Synchrotron DESY, Germany.
    Liermann, Hanns-Peter
    Deutsch Elektronen Synchrotron DESY, Germany.
    Ponomareva, Alena V.
    Natl Univ Sci and Technol MISIS, Russia.
    Tidholm, Johan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Tasnadi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Abrikosov, Igor A.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Dubrovinskaia, Natalia
    Univ Bayreuth, Germany.
    Dubrovinsky, Leonid
    Univ Bayreuth, Germany.
    High-Pressure Synthesis of a Nitrogen-Rich Inclusion Compound ReN8·xN2 with Conjugated Polymeric Nitrogen Chains2018Ingår i: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 57, nr 29, s. 9048-9053Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A nitrogen-rich compound, ReN(8)xN(2), was synthesized by a direct reaction between rhenium and nitrogen at high pressure and high temperature in a laser-heated diamond anvil cell. Single-crystal X-ray diffraction revealed that the crystal structure, which is based on the ReN8 framework, has rectangular-shaped channels that accommodate nitrogen molecules. Thus, despite a very high synthesis pressure, exceeding 100GPa, ReN(8)xN(2) is an inclusion compound. The amount of trapped nitrogen (x) depends on the synthesis conditions. The polydiazenediyl chains [-N=N-] that constitute the framework have not been previously observed in any compound. Abinitio calculations on ReN(8)xN(2) provide strong support for the experimental results and conclusions.

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  • 6.
    Bykov, Maxim
    et al.
    Howard Univ, DC 20059 USA; Carnegie Inst Sci, DC 20015 USA.
    Bykova, Elena
    Howard Univ, DC 20059 USA.
    Ponomareva, Alena V
    Natl Univ Sci & Technol MISIS, Russia.
    Tasnadi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Chariton, Stella
    Univ Chicago, IL 60637 USA.
    Prakapenka, Vitali B.
    Univ Chicago, IL 60637 USA.
    Glazyrin, Konstantin
    Deutsch Electronen Synchrotron DESY, Germany.
    Smith, Jesse S.
    Argonne Natl Lab, IL 60439 USA.
    Mahmood, Mohammad F.
    Howard Univ, DC 20059 USA.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Goncharov, Alexander F.
    Carnegie Inst Sci, DC 20015 USA.
    Realization of an Ideal Cairo Tessellation in Nickel Diazenide NiN2: High-Pressure Route to Pentagonal 2D Materials2021Ingår i: ACS Nano, ISSN 1936-0851, E-ISSN 1936-086X, Vol. 15, nr 8, s. 13539-13546Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Most of the studied two-dimensional (2D) materials are based on highly symmetric hexagonal structural motifs. In contrast, lower-symmetry structures may have exciting anisotropic properties leading to various applications in nano-electronics. In this work we report the synthesis of nickel diazenide NiN2 which possesses atomic-thick layers comprised of Ni2N3 pentagons forming Cairo-type tessellation. The layers of NiN2 are weakly bonded with the calculated exfoliation energy of 0.72 J/m(2), which is just slightly larger than that of graphene. The compound crystallizes in the space group of the ideal Cairo tiling (P4/mbm) and possesses significant anisotropy of elastic properties. The single-layer NiN2 is a direct-band-gap semiconductor, while the bulk material is metallic. This indicates the promise of NiN2 to be a precursor of a pentagonal 2D material with a tunable direct band gap.

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  • 7.
    Bykov, Maxim
    et al.
    Howard Univ, DC 20059 USA; Univ Bayreuth, Germany; Carnegie Inst Sci, DC 20015 USA.
    Chariton, Stella
    Univ Chicago, IL 60437 USA.
    Bykova, Elena
    Carnegie Inst Sci, DC 20015 USA.
    Khandarkhaeva, Saiana
    Univ Bayreuth, Germany.
    Fedotenko, Timofey
    Univ Bayreuth, Germany.
    Ponomareva, Alena V
    Natl Univ Sci and Technol MISIS, Russia.
    Tidholm, Johan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Tasnadi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Sedmak, Pavel
    European Synchrotron Radiat Facil, France.
    Prakapenka, Vitali
    Univ Chicago, IL 60437 USA.
    Hanfland, Michael
    European Synchrotron Radiat Facil, France.
    Liermann, Hanns-Peter
    DESY, Germany.
    Mahmood, Mohammad
    Howard Univ, DC 20059 USA.
    Goncharov, Alexander F.
    Carnegie Inst Sci, DC 20015 USA.
    Doubrovinckaia, Natalia
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten. Univ Bayreuth, Germany.
    Dubrovinsky, Leonid
    Univ Bayreuth, Germany.
    High-Pressure Synthesis of Metal-Inorganic Frameworks Hf4N20 center dot N-2, WN8 center dot N-2, and Os5N28 center dot 3 N-2 with Polymeric Nitrogen Linkers2020Ingår i: Angewandte Chemie International Edition, ISSN 1433-7851, E-ISSN 1521-3773, Vol. 59, nr 26, s. 10321-10326Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Polynitrides are intrinsically thermodynamically unstable at ambient conditions and require peculiar synthetic approaches. Now, a one-step synthesis of metal-inorganic frameworks Hf4N20 center dot N2, WN 8 center dot N2, and Os5N28 center dot 3N2 via direct reactions between elements in a diamond anvil cell at pressures exceeding 100 GPa is reported. The porous frameworks (Hf4N20, WN 8, and Os5N28) are built from transition-metal atoms linked either by polymeric polydiazenediyl (polyacetylene-like) nitrogen chains or through dinitrogen units. Triply bound dinitrogen molecules occupy channels of these frameworks. Owing to conjugated polydiazenediyl chains, these compounds exhibit metallic properties. The high-pressure reaction between Hf and N2 also leads to a non-centrosymmetric polynitride Hf2N11 that features double-helix catenapoly[tetraz-1-ene-1,4-diyl] nitrogen chains [-N-N-N=N-](infinity.)

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  • 8.
    Bykov, Maxim
    et al.
    Univ Bayreuth, Germany.
    Chariton, Stella
    Univ Bayreuth, Germany.
    Fei, Hongzhan
    Univ Bayreuth, Germany.
    Fedotenko, Timofey
    Univ Bayreuth, Germany.
    Aprilis, Georgios
    Univ Bayreuth, Germany.
    Ponomareva, Alena V
    Natl Univ Sci and Technol MISIS, Russia.
    Tasnadi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Merle, Benoit
    Friedrich Alexander Univ Erlangen Nurnberg FAU, Germany.
    Feldners, Patrick
    Friedrich Alexander Univ Erlangen Nurnberg FAU, Germany.
    Vogel, Sebastian
    Univ Munich LMU, Germany.
    Schnick, Wolfgang
    Univ Munich LMU, Germany.
    Prakapenka, Vitali B.
    Univ Chicago, IL 60637 USA.
    Greenberg, Eran
    Univ Chicago, IL 60637 USA.
    Hanfland, Michael
    European Synchrotron Radiat Facil, France.
    Pakhomova, Anna
    DESY, Germany.
    Liermann, Hanns-Peter
    DESY, Germany.
    Katsura, Tomoo
    Univ Bayreuth, Germany.
    Dubrovinskaia, Natalia
    Univ Bayreuth, Germany.
    Dubrovinsky, Leonid
    Univ Bayreuth, Germany.
    High-pressure synthesis of ultraincompressible hard rhenium nitride pernitride Re-2(N-2)(N)(2) stable at ambient conditions2019Ingår i: Nature Communications, E-ISSN 2041-1723, Vol. 10, artikel-id 2994Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    High-pressure synthesis in diamond anvil cells can yield unique compounds with advanced properties, but often they are either unrecoverable at ambient conditions or produced in quantity insufficient for properties characterization. Here we report the synthesis of metallic, ultraincompressible (K-0 = 428(10) GPa), and very hard (nanoindentation hardness 36.7(8) GPa) rhenium nitride pernitride Re-2(N-2)(N)(2). Unlike known transition metals pernitrides Re-2(N-2)(N)(2) contains both pernitride N-2(4-) and discrete N3- anions, which explains its exceptional properties. Re-2(N-2)(N)(2) can be obtained via a reaction between rhenium and nitrogen in a diamond anvil cell at pressures from 40 to 90 GPa and is recoverable at ambient conditions. We develop a route to scale up its synthesis through a reaction between rhenium and ammonium azide, NH4N3, in a large-volume press at 33 GPa. Although metallic bonding is typically seen incompatible with intrinsic hardness, Re-2(N-2)(N)(2) turned to be at a threshold for superhard materials.

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  • 9.
    Bykov, Maxim
    et al.
    Carnegie Inst Sci, DC 20015 USA; Howard Univ, DC 20059 USA.
    Fedotenko, Timofey
    Univ Bayreuth, Germany.
    Chariton, Stella
    Univ Chicago, IL 60637 USA.
    Laniel, Dominique
    Univ Bayreuth, Germany.
    Glazyrin, Konstantin
    Deutsch Electronen Synchrotron DESY, Germany.
    Hanfland, Michael
    European Synchrotron Radiat Facil, France.
    Smith, Jesse S.
    Argonne Natl Lab, IL 60439 USA.
    Prakapenka, Vitali B.
    Univ Chicago, IL 60637 USA.
    Mahmood, Mohammad F.
    Howard Univ, DC 20059 USA.
    Goncharov, Alexander F.
    Carnegie Inst Sci, DC 20015 USA.
    Ponomareva, Alena V
    Natl Univ Sci & Technol MISIS, Russia.
    Tasnadi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Abrikossov, Alexei
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Masood, Talha Bin
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Hotz, Ingrid
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Medie- och Informationsteknik. Linköpings universitet, Tekniska fakulteten.
    Rudenko, Alexander N.
    Wuhan Univ, Peoples R China; Wuhan Univ, Peoples R China; Radboud Univ Nijmegen, Netherlands; Ural Fed Univ, Russia.
    Katsnelson, Mikhail I
    Radboud Univ Nijmegen, Netherlands; Ural Fed Univ, Russia.
    Doubrovinckaia, Natalia
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten. Univ Bayreuth, Germany.
    Dubrovinsky, Leonid
    Univ Bayreuth, Germany.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    High-Pressure Synthesis of Dirac Materials: Layered van der Waals Bonded BeN4 Polymorph2021Ingår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 126, nr 17, artikel-id 175501Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    High-pressure chemistry is known to inspire the creation of unexpected new classes of compounds with exceptional properties. Here, we employ the laser-heated diamond anvil cell technique for synthesis of a Dirac material BeN4. A triclinic phase of beryllium tetranitride tr-BeN4 was synthesized from elements at similar to 85 GPa. Upon decompression to ambient conditions, it transforms into a compound with atomic-thick BeN4 layers interconnected via weak van der Waals bonds and consisting of polyacetylene-like nitrogen chains with conjugated pi systems and Be atoms in square-planar coordination. Theoretical calculations for a single BeN4 layer show that its electronic lattice is described by a slightly distorted honeycomb structure reminiscent of the graphene lattice and the presence of Dirac points in the electronic band structure at the Fermi level. The BeN4 layer, i.e., beryllonitrene, represents a qualitatively new class of 2D materials that can be built of a metal atom and polymeric nitrogen chains and host anisotropic Dirac fermions.

  • 10.
    Darakchieva, Vanya
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Xie, Mengyao
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Tasnadi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Monemar, Bo
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Kamimura, J
    Sophia University.
    Kishino, K
    Japan Science & Technology Agency.
    Lattice parameters, deviations from Vegards rule, and E-2 phonons in InAlN2008Ingår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 93, nr 26, s. 261908-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The lattice parameters of InxAl1-xN in the whole compositional range are studied using first-principle calculations. Deviations from Vegards rule are obtained via the bowing parameters, delta(a)=0.0412 +/- 0.0039 A and delta(c)=-0.060 +/- 0.010 A, which largely differ from previously reported values. Implications of the observed deviations from Vegards rule on the In content extracted from x-ray diffraction are discussed. We also combine these results with x-ray diffraction and Raman scattering studies on InxAl1-xN nanocolumns with 0.627 <= x <= 1 and determine the E-2 phonon frequencies versus In composition in the scarcely studied In-rich compositional range.

  • 11.
    Dubrovinsky, Leonid
    et al.
    Univ Bayreuth, Germany.
    Khandarkhaeva, Saiana
    Univ Bayreuth, Germany; Univ Bayreuth, Germany.
    Fedotenko, Timofey
    Deutsch Elektronen Synchrotron DESY, Germany.
    Laniel, Dominique
    Univ Bayreuth, Germany.
    Bykov, Maxim
    Univ Cologne, Germany.
    Giacobbe, Carlotta
    European Synchrotron Radiat Facil, France.
    Lawrence Bright, Eleanor
    European Synchrotron Radiat Facil, France.
    Sedmak, Pavel
    European Synchrotron Radiat Facil, France.
    Chariton, Stella
    Univ Chicago, IL 60637 USA.
    Prakapenka, Vitali
    Univ Chicago, IL 60637 USA.
    Ponomareva, Alena V.
    Natl Univ Sci & Technol MISIS, Russia.
    Smirnova, Ekaterina A.
    Natl Univ Sci & Technol MISIS, Russia.
    Belov, Maxim P.
    Natl Univ Sci & Technol MISIS, Russia.
    Tasnadi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Shulumba, Nina
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Trybel, Florian
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Abrikosov, Igor A.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Dubrovinskaia, Natalia
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten. Univ Bayreuth, Germany.
    Materials synthesis at terapascal static pressures2022Ingår i: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 605, nr 7909, s. 274-278Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Theoretical modelling predicts very unusual structures and properties of materials at extreme pressure and temperature conditions(1,2). Hitherto, their synthesis and investigation above 200 gigapascals have been hindered both by the technical complexity of ultrahigh-pressure experiments and by the absence of relevant in situ methods of materials analysis. Here we report on a methodology developed to enable experiments at static compression in the terapascal regime with laser heating. We apply this method to realize pressures of about 600 and 900 gigapascals in a laser-heated double-stage diamond anvil cell(3), producing a rhenium-nitrogen alloy and achieving the synthesis of rhenium nitride Re7N3-which, as our theoretical analysis shows, is only stable under extreme compression. Full chemical and structural characterization of the materials, realized using synchrotron single-crystal X-ray diffraction on microcrystals in situ, demonstrates the capabilities of the methodology to extend high-pressure crystallography to the terapascal regime.

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  • 12.
    Ekholm, Marcus
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Gambino, Davide
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Jönsson, Johan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Tasnadi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Alling, Björn
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten. Max Planck Inst Eisenforsch GmbH, Germany.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten. Natl Univ Sci and Technol MISIS, Russia.
    Assessing the SCAN functional for itinerant electron ferromagnets2018Ingår i: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 98, nr 9, artikel-id 094413Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Density functional theory is a standard model for condensed-matter theory and computational material science. The accuracy of density functional theory is limited by the accuracy of the employed approximation to the exchange-correlation functional. Recently, the so-called strongly constrained appropriately normed (SCAN) [Sun, Ruzsinszky, and Perdew, Phys. Rev. Lett. 115, 036402 (2015)] functional has received a lot of attention due to promising results for covalent, metallic, ionic, as well as hydrogen- and van der Waals-bonded systems alike. In this work, we focus on assessing the performance of the SCAN functional for itinerant magnets by calculating basic structural and magnetic properties of the transition metals Fe, Co, and Ni. We find that although structural properties of bcc-Fe seem to be in good agreement with experiment, SCAN performs worse than standard local and semilocal functionals for fcc-Ni and hcp-Co. In all three cases, the magnetic moment is significantly overestimated by SCAN, and the 3d states are shifted to lower energies, as compared to experiments.

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  • 13.
    Ekholm, Marcus
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Tasnádi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Supercell Calculations of Hyperfine Interactions in Transition-Metal AlloysManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    We have performed calculations for the hyperfine field in the disordered Fe0.5Ni0.5 alloy using supercells with up to 864 atoms. The computational scheme is based on exact muffin-tin orbitals and the locally self-consistent Green’s function formalism, which scales linearly with the number of atoms in the supercell. This scheme allows local environment effects, such as chemical and magnetic environment, and short-range order, to be explicitly included. Supercell calculations for Fe-Ni show that while the average fields coincides with that obtained using the coherent potential approximation, there is a significant distribution of the hyperfine fields depending on the local environment. The fields of Fe and Ni show qualitatively different behaviour as a function of the on-site magnetic moment, but scale linearly with the average magnetic moment in the first coordination shell.

  • 14.
    Ektarawong, Annop
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Simak, Sergey
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Tasnádi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Wang, Fei
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Alling, Björn
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. Max Planck Institute Eisenforsch GmbH, Germany.
    Effects of configurational disorder on the elastic properties of icosahedral boron-rich alloys based on B6O, B13C2, and B4C, and their mixing thermodynamics2016Ingår i: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 144, nr 13, artikel-id 134503Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The elastic properties of alloys between boron suboxide (B6O) and boron carbide (B13C2), denoted by (B6O)1−x(B13C2)x, as well as boron carbide with variable carbon content, ranging from B13C2 to B4C are calculated from first-principles. Furthermore, the mixing thermodynamics of (B6O)1−x(B13C2)x is studied. A superatom-special quasirandom structure approach is used for modeling different atomic configurations, in which effects of configurational disorder between the carbide and suboxide structural units, as well as between boron and carbon atoms within the units, are taken into account. Elastic properties calculations demonstrate that configurational  disorder in B13C2, where a part of the C atoms in the CBC chains substitute for B atoms in the B12 icosahedra, drastically increase the Young’s and shear modulus, as compared to an atomically ordered state, B12(CBC). These calculated elastic moduli of the disordered state are in excellent agreement with experiments. Configurational disorder between boron and carbon can also explain the experimentally observed almost constant elastic moduli of boron carbide as the carbon content is changed from B4C to B13C2. The elastic moduli of the (B6O)1−x(B13C2)x system are also practically unchanged with composition if boron-carbon disorder is taken into account. By investigating the mixing thermodynamics of the alloys, in which the Gibbs free energy is determined within the mean-field approximation for the configurational entropy, we outline the pseudo-binary phase diagram of (B6O)1−x(B13C2)x. The phase diagram reveals the existence of a miscibility gap at all temperatures up to the melting point. Also, the coexistence of B6O-rich as well as ordered or disordered B13C2-rich domains in the material prepared through equilibrium routes is predicted.

  • 15.
    Feng, Qingguo
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Ekholm, Marcus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Tasnadi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Jönsson, Johan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten. NUST MISIS, Russia.
    Topological transitions of the Fermi surface of osmium under pressure: an LDA plus DMFT study2017Ingår i: New Journal of Physics, E-ISSN 1367-2630, Vol. 19, artikel-id 033020Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The influence of pressure on the electronic structure of Os has attracted substantial attention recently due to reports on isostructural electronic transitions in this metal. Here, we theoretically investigate the Fermi surface of Os from ambient to high pressure, using density functional theory combined with dynamical mean field theory. Weprovide a detailed discussion of the calculated Fermi surface and its dependence on the level of theory used for the treatment of the electron-electron interactions. Although we confirm that Os can be classified as weakly correlated metal, the inclusion of local quantum fluctuations between 5d electrons beyond the local density approximation explains the most recent experimental reports regarding the occurrence of electronic topological transitions in Os.

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  • 16.
    Ghafoor, Naureen
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Lind, Hans
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Tasnadi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Anomalous epitaxial stability of (001) interfaces in ZrN/SiNx multilayers2014Ingår i: APL Materials, E-ISSN 2166-532X, Vol. 2, nr 4, s. 046106-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Isostructural stability of B1-NaCl type SiN on (001) and (111) oriented ZrN surfaces is studied theoretically and experimentally. The ZrN/SiNx/ZrN superlattices with modulation wavelength of 3.76 nm (dSiNx similar to 0.4 nm) were grown by dc-magnetron sputtering on MgO(001) and MgO(111). The results indicate that 0.4 nm thin SiNx layers utterly influence the preferred orientation of epitaxial growth: on MgO(001) cube-on-cube epitaxy of ZrN/SiNx superlattices were realized whereas multilayers on MgO(111) surface exhibited an unexpected 002 texture with a complex fourfold 90 degrees-rotated in-plane preferred orientation. Density functional theory calculations confirm stability of a (001) interface with respect to a (111) which explains the anomaly.

  • 17.
    Glazyrin, K.
    et al.
    Bayerisches Geoinstitut, Universität Bayreuth, Germany.
    Pourovskii, L.
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Dubrovinsky, L.
    Bayerisches Geoinstitut, Universität Bayreuth, Germany.
    Narygina, O.
    School of Physics and Astronomy, University of Edinburgh, Edinburgh, UK.
    McCammon, C.
    Bayerisches Geoinstitut, Universität Bayreuth, Germany.
    Hewener, B.
    Technische Universität Kaiserslautern, Kaiserslautern, Germany.
    Schünemann, V.
    Technische Universität Kaiserslautern, Kaiserslautern, Germany.
    Wolny, J.
    Technische Universität Kaiserslautern, Kaiserslautern, Germany.
    Muffler, K.
    Technische Universität Kaiserslautern, Kaiserslautern, Germany.
    Chumakov, A. I.
    ESRF, Grenoble Cedex, France.
    Crichton, W.
    ESRF, Grenoble Cedex, France.
    Hanfland, M.
    ESRF, Grenoble Cedex, France.
    Prakapenka, V.
    GeoSoilEnviroCARS, University of Chicago, Argonne National Laboratory, USA.
    Tasnádi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Ekholm, Marcus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Aichhorn, M.
    Centro Atómico Constituyentes, GIyANN, CNEA, San Martin, Buenos Aires, Comisión Nacional de Investigaciones Científicas y Técnicas, Ciudad de Buenos Aires, Argentina.
    Vildosola, V.
    Centro Atómico Constituyentes, GIyANN, CNEA, San Martin, Buenos Aires, Comisión Nacional de Investigaciones Científicas y Técnicas, Ciudad de Buenos Aires, Argentina.
    Ruban, A. V.
    12Department of Materials Science and Engineering, Royal Institute of Technology, Stockholm, Sweden.
    Katsnelson, M. I.
    Radboud University Nijmegen, Institute for Molecules and Materials, Netherlands.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Importance of correlation effects in hcp iron revealed by a pressure-induced electronic topological transition2013Ingår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 110, nr 11Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We discover that hcp phases of Fe and Fe0.9Ni0.1 undergo an electronic topological transition at pressures of about 40 GPa. This topological change of the Fermi surface manifests itself through anomalous behavior of the Debye sound velocity, c/a lattice parameter ratio, and Mossbauer center shift observed in our experiments. First-principles simulations within the dynamic mean field approach demonstrate that the transition is induced by many-electron effects. It is absent in one-electron calculations and represents a clear signature of correlation effects in hcp Fe. DOI: 10.1103/PhysRevLett.110.117206

  • 18.
    Gubaev, Konstantin
    et al.
    Delft Univ Technol, Netherlands; Univ Stuttgart, Germany.
    Ikeda, Yuji
    Univ Stuttgart, Germany.
    Tasnadi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Neugebauer, Joerg
    Max Planck Inst Eisenforsch GmbH, Germany.
    Shapeev, Alexander V
    Skolkovo Inst Sci & Technol, Russia.
    Grabowski, Blazej
    Univ Stuttgart, Germany.
    Koermann, Fritz
    Delft Univ Technol, Netherlands; Max Planck Inst Eisenforsch GmbH, Germany.
    Finite-temperature interplay of structural stability, chemical complexity, and elastic properties of bcc multicomponent alloys from ab initio trained machine-learning potentials2021Ingår i: Physical Review Materials, E-ISSN 2475-9953, Vol. 5, nr 7, artikel-id 073801Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    An active learning approach to train machine-learning interatomic potentials (moment tensor potentials) for multicomponent alloys to ab initio data is presented. Employing this approach, the disordered body-centered cubic (bcc) TiZrHfTax system with varying Ta concentration is investigated via molecular dynamics simulations. Our results show a strong interplay between elastic properties and the structural. phase stability, strongly affecting the mechanical properties. Based on these insights we systematically screen composition space for regimes where elastic constants show little or no temperature dependence (elinvar effect).

  • 19.
    Holec, D.
    et al.
    Mt University of Leoben, Austria.
    Tasnadi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Wagner, P.
    Mt University of Leoben, Austria.
    Friak, M.
    Max Planck Institute Eisenforsch GmbH, Germany; Academic Science Czech Republic, Czech Republic.
    Neugebauer, J.
    Max Planck Institute Eisenforsch GmbH, Germany.
    Mayrhofer, P. H.
    Vienna University of Technology, Austria.
    Keckes, J.
    Austrian Academic Science, Austria; Mt University of Leoben, Austria.
    Macroscopic elastic properties of textured ZrN-AlN polycrystalline aggregates: From ab initio calculations to grainscale interactions2014Ingår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 90, nr 18, s. 184106-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Despite the fast development of computational material modeling, the theoretical description of macroscopic elastic properties of textured polycrystalline aggregates starting from basic principles remains a challenging task. In this study we use a supercell-based approach to obtain the elastic properties of a random solid solution cubic Zr1-x Al-x N system as a function of the metallic sublattice composition and texture descriptors. The employed special quasirandom structures are optimized not only with respect to short-range-order parameters, but also to make the three cubic directions [1 0 0], [0 1 0], and [0 0 1] as similar as possible. In this way, only a small spread of elastic constant tensor components is achieved and an optimum trade-off between modeling of chemical disorder and computational limits regarding the supercell size and calculational time is proposed. The single-crystal elastic constants are shown to vary smoothly with composition, yielding x approximate to 0.5 an alloy constitution with an almost isotropic response. Consequently, polycrystals with this composition are suggested to have Youngs modulus independent of the actual microstructure. This is indeed confirmed by explicit calculations of polycrystal elastic properties, both within the isotropic aggregate limit and with fiber textures with various orientations and sharpness. It turns out that for low AlN mole fractions, the spread of the possible Youngs modulus data caused by the texture variation can be larger than 100 GPa. Consequently, our discussion of Youngs modulus data of cubic Zr1-x Al-x N contains also the evaluation of the texture typical for thin films.

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  • 20.
    Johansson, Erik
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Tasnadi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Ektarawong, Annop
    Chulalongkorn Univ, Thailand; Minist Higher Educ Sci Res & Innovat, Thailand.
    Rosén, Johanna
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Materialdesign. Linköpings universitet, Tekniska fakulteten.
    Alling, Björn
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    The effect of strain and pressure on the electron-phonon coupling and superconductivity in MgB2-Benchmark of theoretical methodologies and outlook for nanostructure design2022Ingår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 131, nr 6, artikel-id 063902Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Different theoretical methodologies are employed to investigate the effect of hydrostatic pressure and anisotropic stress and strain on the superconducting transition temperature ( T-c) of MgB2. This is done both by studying Kohn anomalies in the phonon dispersions alone and by explicit calculation of the electron-phonon coupling. It is found that increasing pressure suppresses T-c in all cases, whereas isotropic and anisotropic strain enhances the superconductivity. In contrast to trialed epitaxial growth that is limited in the amount of achievable lattice strain, we propose a different path by co-deposition with ternary diborides that thermodynamically avoid mixing with MgB2. This is suggested to promote columnar growth that can introduce strain in all directions.

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  • 21.
    Laniel, Dominique
    et al.
    Centre for Science at Extreme Conditions and School of Physics and Astronomy University of Edinburgh Edinburgh EH9 3FD UK;Material Physics and Technology at Extreme Conditions Laboratory of Crystallography University of Bayreuth 95440 Bayreuth Germany.
    Trybel, Florian
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Aslandukov, Andrey
    Material Physics and Technology at Extreme Conditions Laboratory of Crystallography University of Bayreuth 95440 Bayreuth Germany;Bayerisches Geoinstitut University of Bayreuth 95440 Bayreuth Germany.
    Khandarkhaeva, Saiana
    Material Physics and Technology at Extreme Conditions Laboratory of Crystallography University of Bayreuth 95440 Bayreuth Germany.
    Fedotenko, Timofey
    Photon Science Deutsches Elektronen‐Synchrotron Notkestrasse 85 22607 Hamburg Germany.
    Yin, Yuqing
    Material Physics and Technology at Extreme Conditions Laboratory of Crystallography University of Bayreuth 95440 Bayreuth Germany;State Key Laboratory of Crystal Materials Shandong University Jinan 250100 China.
    Miyajima, Nobuyoshi
    Bayerisches Geoinstitut University of Bayreuth 95440 Bayreuth Germany.
    Tasnadi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Ponomareva, Alena V.
    Materials Modeling and Development Laboratory NUST “MISIS” Moscow 119049 Russia.
    Jena, Nityasagar
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Akbar, Fariia Iasmin
    Bayerisches Geoinstitut University of Bayreuth 95440 Bayreuth Germany.
    Winkler, Bjoern
    Institut für Geowissenschaften Abteilung Kristallographie Johann Wolfgang Goethe‐Universität Frankfurt Altenhöferallee 1 D‐60438 Frankfurt am Main Germany.
    Néri, Adrien
    Bayerisches Geoinstitut University of Bayreuth 95440 Bayreuth Germany.
    Chariton, Stella
    Center for Advanced Radiation Sources University of Chicago Chicago IL 60637 USA.
    Prakapenka, Vitali
    Center for Advanced Radiation Sources University of Chicago Chicago IL 60637 USA.
    Milman, Victor
    Dassault Systèmes BIOVIA Cambridge CB4 0FJ UK.
    Schnick, Wolfgang
    Department of Chemistry University of Munich (LMU) Butenandtstrasse 5–13 81377 Munich Germany.
    Rudenko, Alexander N.
    Radboud University Institute for Molecules and Materials Heijendaalseweg 135 Nijmegen 6525 AJ The Netherlands.
    Katsnelson, Mikhail I.
    Radboud University Institute for Molecules and Materials Heijendaalseweg 135 Nijmegen 6525 AJ The Netherlands.
    Abrikosov, Igor A.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Dubrovinsky, Leonid
    Bayerisches Geoinstitut University of Bayreuth 95440 Bayreuth Germany.
    Doubrovinckaia, Natalia
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten. Material Physics and Technology at Extreme Conditions Laboratory of Crystallography University of Bayreuth 95440 Bayreuth Germany.
    Synthesis of Ultra‐Incompressible and Recoverable Carbon Nitrides Featuring CN4 Tetrahedra2024Ingår i: Advanced Materials, ISSN 0935-9648, E-ISSN 1521-4095, Vol. 36, nr 3, artikel-id 2308030Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Carbon nitrides featuring three-dimensional frameworks of CN4 tetrahedra are one of the great aspirations of materials science, expected to have a hardness greater than or comparable to diamond. After more than three decades of efforts to synthesize them, no unambiguous evidence of their existence has been delivered. Here, the high-pressure high-temperature synthesis of three carbon-nitrogen compounds, tI14-C3N4, hP126-C3N4, and tI24-CN2, in laser-heated diamond anvil cells, is reported. Their structures are solved and refined using synchrotron single-crystal X-ray diffraction. Physical properties investigations show that these strongly covalently bonded materials, ultra-incompressible and superhard, also possess high energy density, piezoelectric, and photoluminescence properties. The novel carbon nitrides are unique among high-pressure materials, as being produced above 100 GPa they are recoverable in air at ambient conditions.

  • 22.
    Laniel, Dominique
    et al.
    Material Physics and Technology at Extreme Conditions, Laboratory of Crystallography, University of Bayreuth, 95440 Bayreuth, Germany; Centre for Science at Extreme Conditions and School of Physics and Astronomy, University of Edinburgh, EH9 3FD Edinburgh, UK.
    Trybel, Florian
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Néri, Adrien
    Bayerisches Geoinstitut, University of Bayreuth, 95440 Bayreuth, Germany.
    Yin, Yuqing
    Material Physics and Technology at Extreme Conditions, Laboratory of Crystallography, University of Bayreuth, 95440 Bayreuth, Germany; State Key Laboratory of Crystal Materials, Shandong University, Jinan, 250100 P. R. China.
    Aslandukov, Andrey
    Material Physics and Technology at Extreme Conditions, Laboratory of Crystallography, University of Bayreuth, 95440 Bayreuth, Germany; Bayerisches Geoinstitut, University of Bayreuth, 95440 Bayreuth, Germany.
    Fedotenko, Timofey
    Deutsches Elektronen-Synchrotron, Notkestr. 85, 22607 Hamburg, Germany.
    Khandarkhaeva, Saiana
    Bayerisches Geoinstitut, University of Bayreuth, 95440 Bayreuth, Germany.
    Tasnadi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Chariton, Stella
    Center for Advanced Radiation Sources, University of Chicago, Chicago, IL 60637 USA.
    Giacobbe, Carlotta
    European Synchrotron Radiation Facility, B.P. 220, 38043 Grenoble Cedex, France.
    Bright, Eleanor Lawrence
    European Synchrotron Radiation Facility, B.P. 220, 38043 Grenoble Cedex, France.
    Hanfland, Michael
    European Synchrotron Radiation Facility, B.P. 220, 38043 Grenoble Cedex, France.
    Prakapenka, Vitali
    Center for Advanced Radiation Sources, University of Chicago, Chicago, IL 60637 USA.
    Schnick, Wolfgang
    Department of Chemistry, University of Munich (LMU), Butenandtstrasse 5–13, 81377 Munich, Germany.
    Abrikosov, Igor A.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Dubrovinsky, Leonid
    Bayerisches Geoinstitut, University of Bayreuth, 95440 Bayreuth, Germany.
    Doubrovinckaia, Natalia
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten. Material Physics and Technology at Extreme Conditions, Laboratory of Crystallography, University of Bayreuth, 95440 Bayreuth, Germany.
    Front Cover: Revealing Phosphorus Nitrides up to the Megabar Regime: Synthesis of α′-P3N5, δ-P3N5 and PN2 (Chem. Eur. J. 62/2022)2022Ingår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 28, nr 62, artikel-id e202203122Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    For the last 30 years, the lack of a binary phosphorus nitride containing PN6 octahedra formed a scientific chasm between carbon-group and oxygen-group nitrides, both featuring a variety of solids with XN6 units (X being a non-metal element). Now, the discovery of the δ-P3N5 and PN2 phosphorus nitrides—formed under high pressure and both composed of the elusive PN6 octahedron—builds a long-sought-after bridge between these two groups of nitrides. More information can be found in the Research Article by D. Laniel, F. Trybel, and co-workers (DOI: 10.1002/chem.202201998).

  • 23.
    Laniel, Dominique
    et al.
    Univ Bayreuth, Germany; Univ Edinburgh, Scotland; Univ Edinburgh, Scotland.
    Trybel, Florian
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Néri, Adrien
    Univ Bayreuth, Germany.
    Yin, Yuqing
    Univ Bayreuth, Germany; Shandong Univ, Peoples R China.
    Aslandukov, Andrey
    Univ Bayreuth, Germany; Univ Bayreuth, Germany.
    Fedotenko, Timofey
    Deutsch Elekt Synchrotron, Germany.
    Khandarkhaeva, Saiana
    Univ Bayreuth, Germany.
    Tasnadi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Chariton, Stella
    Univ Chicago, IL 60637 USA.
    Giacobbe, Carlotta
    European Synchrotron Radiat Facil, France.
    Bright, Eleanor Lawrence
    European Synchrotron Radiat Facil, France.
    Hanfland, Michael
    European Synchrotron Radiat Facil, France.
    Prakapenka, Vitali
    Univ Chicago, IL 60637 USA.
    Schnick, Wolfgang
    Univ Munich LMU, Germany.
    Abrikosov, Igor A.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Dubrovinsky, Leonid
    Univ Bayreuth, Germany.
    Doubrovinckaia, Natalia
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten. Univ Bayreuth, Germany.
    Revealing Phosphorus Nitrides up to the Megabar Regime: Synthesis of α′‐P3N5, δ‐P3N5 and PN22022Ingår i: Chemistry - A European Journal, ISSN 0947-6539, E-ISSN 1521-3765, Vol. 28, nr 62, artikel-id e202201998Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Non-metal nitrides are an exciting field of chemistry, featuring a significant number of compounds that can possess outstanding material properties. These properties mainly rely on maximizing the number of strong covalent bonds, with crosslinked XN6 octahedra frameworks being particularly attractive. In this study, the phosphorus-nitrogen system was studied up to 137 GPa in laser-heated diamond anvil cells, and three previously unobserved phases were synthesized and characterized by single-crystal X-ray diffraction, Raman spectroscopy measurements and density functional theory calculations. delta-P3N5 and PN2 were found to form at 72 and 134 GPa, respectively, and both feature dense 3D networks of the so far elusive PN6 units. The two compounds are ultra-incompressible, having a bulk modulus of K-0=322 GPa for delta-P3N5 and 339 GPa for PN2. Upon decompression below 7 GPa, delta-P3N5 undergoes a transformation into a novel alpha -P3N5 solid, stable at ambient conditions, that has a unique structure type based on PN4 tetrahedra. The formation of alpha -P3N5 underlines that a phase space otherwise inaccessible can be explored through materials formed under high pressure.

  • 24.
    Levämäki, Henrik
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Bock, Florian
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Sangiovanni, Davide
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Johnson, Lars J. S.
    Sandvik Coromant, Sweden.
    Tasnadi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Armiento, Rickard
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    HADB: A materials-property database for hard-coating alloys2023Ingår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 766, artikel-id 139627Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Data-driven approaches are becoming increasingly valuable for modern science, and they are making their way into industrial research and development (R&D). Supervised machine learning of statistical models can utilize databases of materials parameters to speed up the exploration of candidate materials for experimental synthesis and characterization. In this paper we introduce the HADB database, which contains properties of industrially relevant chemically disordered hard-coating alloys, focusing on their thermodynamic, elastic and mechanical properties. We present the technical implementations of the database infrastructure including support for browse, query, retrieval, and API access through the OPTIMADE API to make this data findable, accessible, interoperable, and reusable (FAIR). Finally, we demonstrate the usefulness of the database by training a graph -based machine learning (ML) model to predict elastic properties of hard-coating alloys. The ML model is shown to predict bulk and shear moduli for out out-of-sample alloys with less than 6 GPa mean average error.

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  • 25.
    Levämäki, Henrik
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Tasnadi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Sangiovanni, Davide
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Johnson, L. J. S.
    Sandvik Coromant, Sweden.
    Armiento, Rickard
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten. Natl Univ Sci & Technol MISIS, Russia.
    Predicting elastic properties of hard-coating alloys using ab-initio and machine learning methods2022Ingår i: npj Computational Materials, E-ISSN 2057-3960, Vol. 8, nr 1, artikel-id 17Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Accelerated design of hard-coating materials requires state-of-the-art computational tools, which include data-driven techniques, building databases, and training machine learning models. We develop a heavily automated high-throughput workflow to build a database of industrially relevant hard-coating materials, such as binary and ternary nitrides. We use the high-throughput toolkit to automate the density functional theory calculation workflow. We present results, including elastic constants that are a key parameter determining mechanical properties of hard-coatings, for X1-xYxN ternary nitrides, where X,Y ∈ {Al, Ti, Zr, Hf} and fraction . We also explore ways for machine learning to support and complement the designed databases. We find that the crystal graph convolutional neural network trained on ordered lattices has sufficient accuracy for the disordered nitrides, suggesting that existing databases provide important data for predicting mechanical properties of qualitatively different types of materials, in our case disordered hard-coating alloys.

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  • 26.
    Liang, Akun
    et al.
    Univ Edinburgh, Scotland; Univ Edinburgh, Scotland.
    Osmond, Israel
    Univ Edinburgh, Scotland; Univ Edinburgh, Scotland.
    Krach, Georg
    Univ Munich LMU, Germany.
    Shi, Lan-Ting
    Spallat Neutron Source Sci Ctr, Peoples R China.
    Bruening, Lukas
    Univ Cologne, Germany.
    Ranieri, Umbertoluca
    Univ Edinburgh, Scotland; Univ Edinburgh, Scotland.
    Spender, James
    Univ Edinburgh, Scotland; Univ Edinburgh, Scotland.
    Tasnadi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Massani, Bernhard
    Univ Edinburgh, Scotland; Univ Edinburgh, Scotland.
    Stevens, Callum R.
    Univ Edinburgh, Scotland; Univ Edinburgh, Scotland.
    McWilliams, Ryan Stewart
    Univ Edinburgh, Scotland; Univ Edinburgh, Scotland.
    Bright, Eleanor Lawrence
    European Synchrotron Radiat Facil, France.
    Giordano, Nico
    Photon Sci, Germany.
    Gallego-Parra, Samuel
    European Synchrotron Radiat Facil, France.
    Yin, Yuqing
    Univ Bayreuth, Germany.
    Aslandukov, Andrey
    Univ Bayreuth, Germany.
    Akbar, Fariia Iasmin
    Univ Bayreuth, Germany.
    Gregoryanz, Eugene
    Univ Edinburgh, Scotland; Univ Edinburgh, Scotland; Ctr High Pressure Sci & Technol Adv Res, Peoples R China; Inst Solid State Phys, Peoples R China.
    Huxley, Andrew
    Univ Edinburgh, Scotland; Univ Edinburgh, Scotland.
    Pena-Alvarez, Miriam
    Univ Edinburgh, Scotland; Univ Edinburgh, Scotland.
    Si, Jian-Guo
    Spallat Neutron Source Sci Ctr, Peoples R China.
    Schnick, Wolfgang
    Univ Munich LMU, Germany.
    Bykov, Maxim
    Univ Cologne, Germany; Goethe Univ Frankfurt, Germany.
    Trybel, Florian
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Laniel, Dominique
    Univ Edinburgh, Scotland; Univ Edinburgh, Scotland.
    High-Pressure Synthesis of Ultra-Incompressible, Hard and Superconducting Tungsten Nitrides2024Ingår i: Advanced Functional Materials, ISSN 1616-301X, E-ISSN 1616-3028Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Transition metal nitrides, particularly those of 5d metals, are known for their outstanding properties, often relevant for industrial applications. Among these metal elements, tungsten is especially attractive given its low cost. In this high-pressure investigation of the W-N system, two novel ultra-incompressible tungsten nitride superconductors, namely W2N3 and W3N5, are successfully synthesized at 35 and 56 GPa, respectively, through a direct reaction between N2 and W in laser-heated diamond anvil cells. Their crystal structure is determined using synchrotron single-crystal X-ray diffraction. While the W2N3 solid's sole constituting nitrogen species are N3- units, W3N5 features both discrete N3- as well as N24- pernitride anions. The bulk modulus of W2N3 and W3N5 is experimentally determined to be 380(3) and 406(7) GPa, and their ultra-incompressible behavior is rationalized by their constituting WN7 polyhedra and their linkages. Importantly, both W2N3 and W3N5 are recoverable to ambient conditions and stable in air. Density functional theory calculations reveal W2N3 and W3N5 to have a Vickers hardness of 30 and 34 GPa, and superconducting transition temperatures at ambient pressure (50 GPa) of 11.6 K (9.8 K) and 9.4 K (7.2 K), respectively. Additionally, transport measurements performed at 50 GPa on W2N3 corroborate with the calculations. Two recoverable tungsten nitrides, namely W2N3 and W3N5, are synthesized using laser-heated diamond anvil cells. Both compounds exhibit a high bulk modulus, hardness, and superconducting transition temperature. image

  • 27.
    Lin, Shuyao
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska fakulteten. Tech Univ Wien, Austria.
    Casillas-Trujillo, Luis
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska fakulteten.
    Tasnadi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Mayrhofer, Paul H.
    Tech Univ Wien, Austria.
    Sangiovanni, Davide
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Koutna, Nikola
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten. Tech Univ Wien, Austria.
    Machine-learning potentials for nanoscale simulations of tensile deformation and fracture in ceramics2024Ingår i: npj Computational Materials, E-ISSN 2057-3960, Vol. 10, nr 1, artikel-id 67Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Machine-learning interatomic potentials (MLIPs) offer a powerful avenue for simulations beyond length and timescales of ab initio methods. Their development for investigation of mechanical properties and fracture, however, is far from trivial since extended defects-governing plasticity and crack nucleation in most materials-are too large to be included in the training set. Using TiB2 as a model ceramic material, we propose a training strategy for MLIPs suitable to simulate mechanical response of monocrystals until failure. Our MLIP accurately reproduces ab initio stresses and fracture mechanisms during room-temperature uniaxial tensile deformation of TiB2 at the atomic scale ( approximate to 103 atoms). More realistic tensile tests (low strain rate, Poisson's contraction) at the nanoscale ( approximate to 104-106 atoms) require MLIP up-fitting, i.e., learning from additional ab initio configurations. Consequently, we elucidate trends in theoretical strength, toughness, and crack initiation patterns under different loading directions. As our MLIP is specifically trained to modelling tensile deformation, we discuss its limitations for description of different loading conditions and lattice structures with various Ti/B stoichiometries. Finally, we show that our MLIP training procedure is applicable to diverse ceramic systems. This is demonstrated by developing MLIPs which are subsequently validated by simulations of uniaxial strain and fracture in TaB2, WB2, ReB2, TiN, and Ti2AlB2.

  • 28.
    Lind, Hans
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Forsén, Rikard
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Alling, Björn
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Ghafoor, Naureen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Tasnadi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Johansson, M P
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Improving thermal stability of hard coating films via a concept of multicomponent alloying2011Ingår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 99, nr 9, s. 091903-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We propose a design route for the next generation of nitride alloys via a concept of multicomponent alloying based on self-organization on the nanoscale via a formation of metastable intermediate products during the spinodal decomposition. We predict theoretically and demonstrate experimentally that quasi-ternary (TiCrAl)N alloys decompose spinodally into (TiCr)N and (CrAl)N-rich nanometer sized regions. The spinodal decomposition results in age hardening, while the presence of Cr within the AlN phase delays the formation of a detrimental wurtzite phase leading to a substantial improvement of thermal stability compared to the quasi-binary (TiAl)N or (CrAl)N alloys.

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  • 29.
    Lind, Hans
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Pilemalm, Robert
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Rogström, Lina
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Tasnadi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Ghafoor, Naureen
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Forsén, Rikard
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Johnson, Lars
    Sandvik Coromant, Stockholm, Sweden.
    Jöesaar, Mats
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan. SECO Tools AB, Fagersta, Sweden.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    High temperature phase decomposition in TixZryAlzN2014Ingår i: AIP Advances, E-ISSN 2158-3226, Vol. 4, nr 12, s. 127147-1-127147-9Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Through a combination of theoretical and experimental observations we study the high temperature decomposition behavior of c-(TixZryAlzN) alloys. We show that for most concentrations the high formation energy of (ZrAl)N causes a strong tendency for spinodal decomposition between ZrN and AlN while other decompositions tendencies are suppressed. In addition we observe that entropic  effects due to configurational disorder favor a formation of a stable Zr-rich (TiZr)N phase with increasing temperature. Our calculations also predict that at high temperatures a Zr rich (TiZrAl)N disordered phase should become more resistant against the spinodal decomposition despite its high and positive formation energy due to the specific topology of the free energy surface at the relevant concentrations. Our experimental observations confirm this prediction by showing strong tendency towards decomposition in a Zr-poor sample while a Zr-rich alloy shows a greatly reduced decomposition rate, which is mostly attributable to binodal decomposition processes. This result highlights the importance of considering the second derivative of the free energy, in addition to its absolute value in predicting decomposition trends of thermodynamically unstable alloys.

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  • 30.
    Lind, Hans
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Tasnadi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Systematic theoretical search for alloys with increased thermal stability for advanced hard coatings applications2013Ingår i: New Journal of Physics, E-ISSN 1367-2630, Vol. 15Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    State-of-the-art alloys for hard coating applications, such as TiAlN, are known to suffer from decreased hardness during heat treatment in excess of 900 °C due to the formation of detrimental wurtzite AlN phases. Recent research has shown that multicomponent alloying with additional transition metals (TMs) such as Cr can shift the onset of the phase transformations to higher temperatures, but a search for new alloys is generally time-consuming due to the large number of processes that influence material properties along with the large number of alloy compositions that have to be synthesized. To overcome this difficulty we carry out systematic first-principles calculations aimed at finding potential new multicomponent TM aluminum nitride alloys for advanced hard coating applications. We direct our search towards a specific property, the thermal stability of the coating. In particular, we concentrate on the thermodynamic stability of the cubic B1 TM–Al–N phase relative to the wurtzite phase, and choose the enthalpy difference between them as our search descriptor. We perform ab initio calculations for all TMs, considered as impurities in AlN, and identify the most promising candidates that may improve the thermal stability. We present arguments that these elements should be targeted in future in-depth studies, theoretical, as well as experimental.

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  • 31.
    Lind, Hans
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Tasnádi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Abrikosov, Igor A.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Ti and Cr impurities in cubic and hexagonal AlNManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    AlN is a wide band gap semiconductor that is used in many fields, e.g. as electronic material, for piezoelectric applications but also as a component material in high performance hard coating alloys. The stable structure under ambient conditions is a hexagonal wurtzite structure, but it has also been observed in the tetrahedrally bonded cubic zinc-blende structure as well as cubic rock-salt phases that become stable at high pressure. The metastable rock-salt phase of AlN also forms during decomposition processes in hard-coating alloys such as (TiAl)N, (CrAl)N and (TiCrAl)N. Even though thermodynamically unstable, one can expect some amount of Ti and Cr to be present in the c-AlN phase during the decomposition. Still, little study has been done for the dilute (TMAl)N alloys with cubic B1 crystal structure. We study the electronic structure of Ti and Cr impurities in B1 AlN. Because of the limitations of standard local and semi-local approximations within the density functional theory (DFT) in the treatment of wide band gap semiconductors, as well as conventional hybrid functionals for systems consisting of correlated localized and delocalized orbitals, we apply the mHSE+Vw method, which has been developed specifically to dealing with these kind of problems. Simulations are done by means of the supercell technique with single impurities, as well as for the impurity pairs. The effects of different atomic configurations of the TM-impurities on phase stability and magnetic properties of the cubic B1 AlN is studied and compared to the those in hexagonal B4 structures. Our results underline the importance of correlation and magnetic effects for the description of properties of cubic AlN doped with Ti and Cr.

  • 32.
    Marten, Tobias
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Alling, Björn
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Isaev, Eyvas
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Lind, Hans
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Tasnadi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    First-principles study of the SiNx/TiN(001) interface2012Ingår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 85, nr 10, s. 104106-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The structure of the SiNx tissue phase in superhard TiN/SiNx nanocomposites has been debated in the literature. We present a theoretical investigation of the possibility of crystalline and coherent ( 001) interfaces that satisfies the two necessary criteria, stability with respect to lattice vibrations as well as to variations in stoichiometry. It is found that one monolayer of Si tetrahedrally coordinated by N in a B3-like geometry embedded between B1-TiN( 001) surfaces is both dynamically stable and thermodynamically stable with respect to vacancy formation. However, with increasing layer thickness the B3-type structure becomes unstable with respect to Si vacancy formation. Instead we suggest that a tetragonal D0(22)-like order of Si vacancies can stabilize the interface. These structures are in line with the experimental findings of the crystalline tissue phase which has coherent interfaces with TiN.

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  • 33.
    Mattesini, Maurizio
    et al.
    Universidad Complutense de Madrid.
    Magnuson, Martin
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik.
    Tasnádi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Höglund, Carina
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Abrikosov, Igor A.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Elastic properties and electrostructural correlations in ternary scandium-based cubic inverse perovskites: A first-principles study2009Ingår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 79, nr 125122Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Wehave performed ab initio calculations for the cubic inverse-perovskite Sc3EN(E=Al,Ga,In) systems to study their electronic band-structures and elastic properties.In this study, we used the accurate augmented plane waveplus local orbital method to find the equilibrium structural parametersand to compute the full elastic tensors. The obtained single-crystalelastic constants were used to quantify the stiffness of theSc-based ternary nitrides and to appraise their mechanical stability. Thesite-projected density of states, Fermi surfaces, and the charge-density plotshave also been used to analyze the chemical bonding betweenthe Sc6N cluster and the surrounding metallic lattice of eitherAl, Ga, or In atoms. Our calculations show that Sc3GaNhas the largest covalent Sc-N bonding-type character with the highestYoung, shear, and bulk moduli. Compared with the other twoisoelectronic systems, it also behaves as the most brittle materialwith a relatively large elastic anisotropy.

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  • 34.
    Mikhaylushkin, Arkady
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Höglund, Carina
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Czigany, Zs
    Hungarian Acadamy of Science.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Simak, Sergey
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Alling, Björn
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Tasnadi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Stability of the ternary perovskites Sc3EN (E=B,Al,Ga,In) from first principles2009Ingår i: PHYSICAL REVIEW B, ISSN 1098-0121, Vol. 79, nr 13, s. 134107-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Mechanical and thermodynamic stability of the isoelectronic ternary inverse perovskites Sc3EN (E=B,Al,Ga,In) has been studied from first principles. We confirm stability of recently synthesized cubic phases Sc3AlN and Sc3InN, and predict the stability of cubic Sc3GaN and a triclinic phase aP20-Sc3BN. Substantial phonon softening in Sc3AlN and Sc3GaN is observed indicating a possibility that structural defects could form readily. In accord, our experiments show that magnetron sputter deposited films contain regions with high density of nonperiodic stacking faults along the < 111 > growth direction. We suggest that defect-free crystals may exhibit anomalies in the carrier properties, promising for electronic applications.

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  • 35.
    Norrby, Niklas
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Lind, Hans
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Parakhonskiy, G
    University of Bayreuth, Germany .
    Johansson, M P.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    Tasnadi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Dubrovinsky, L S.
    University of Bayreuth, Germany .
    Dubrovinskaia, N
    University of Bayreuth, Germany .
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska högskolan.
    High pressure and high temperature stabilization of cubic AlN in Ti0.60Al0.40N2013Ingår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 113, nr 5Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In the present work, the decomposition of unstable arc evaporated Ti0.6Al0.4N at elevated temperatures and quasihydrostatic pressures has been studied both experimentally and by first-principles calculations. High pressure and high temperature (HPHT) treatment of the samples was realized using the multi anvil press and diamond anvil cell techniques. The products of the HPHT treatment of Ti0.6Al0.4N were investigated using x-ray diffractometry and transmission electron microscopy. Complimentary calculations show that both hydrostatic pressure and high temperature stabilize the cubic phase of AlN, which is one of the decomposition products of Ti0.6Al0.4N. This is in agreement with the experimental results which in addition suggest that the presence of Ti in the system serves to increase the stability region of the cubic c-AlN phase. The results are industrially important as they show that Ti0.6Al0.4N coatings on cutting inserts do not deteriorate faster under pressure due to the cubic AlN to hexagonal AlN transformation.

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  • 36.
    Rudenko, Alexander N.
    et al.
    Radboud Univ Nijmegen, Netherlands.
    Acharya, Swagata
    Radboud Univ Nijmegen, Netherlands.
    Tasnadi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Pashov, Dimitar
    Kings Coll London, England.
    Ponomareva, Alena V
    NUST MISIS, Russia.
    van Schilfgaarde, Mark
    Kings Coll London, England; Natl Renewable Energy Lab, CO 80401 USA.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Katsnelson, Mikhail I
    Radboud Univ Nijmegen, Netherlands.
    Electronic and optical properties of crystalline nitrogen versus black phosphorus: A comparative first-principles study2022Ingår i: Physical Review B, ISSN 2469-9950, E-ISSN 2469-9969, Vol. 105, nr 20, artikel-id 205135Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Crystalline black nitrogen (BN) is an allotrope of nitrogen with the black phosphorus (BP) structure recently synthesized at high pressure by two independent research groups [Ji et al., Sci. Adv. 6, eaba9206 (2020); Laniel et al., Phys. Rev. Lett. 124, 216001 (2020)]. Here, we present a systematic study of the electronic and optical properties of BN focusing on its comparison with BP. To this end, we use the state-of-the-art quasiparticle self-consistent GW approach with vertex corrections in both the electronic and optical channels. Despite many similarities, the properties of BN are found to be considerably different. Unlike BP, BN exhibits a larger optical gap (2.5 vs 0.26 eV), making BN transparent in the visible spectral region with a highly anisotropic optical response. This difference can be primarily attributed to a considerably reduced dielectric screening in BN, leading to enhancement of the effective Coulomb interaction. Despite relatively strong Coulomb interaction, exciton formation is largely suppressed in both materials. Our analysis of the elastic properties shows exceptionally high stiffness of BN, comparable to that of diamond.

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  • 37.
    Salamania, Janella
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten. Seco Tools AB, Sweden.
    Bock, Florian
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Johnson, L. J. S.
    Sandvik Coromant AB, Sweden.
    Tasnadi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Kwick, K. M. Calamba
    Sandvik Coromant AB, Sweden.
    Farhadizadeh, Alireza
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Rogström, Lina
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    High temperature decomposition and age hardening of single-phase wurtzite Ti1−xAlxN thin films grown by cathodic arc deposition2024Ingår i: Physical Review Materials, E-ISSN 2475-9953, Vol. 8, nr 1, artikel-id 013602Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Wurtzite TmAlN (T-m = transition metal) themselves are of interest as semiconductors with tunable band gap, insulating motifs to superconductors, and piezoelectric crystals. Characterization of wurtzite TmAlN is challenging because of the difficulty to synthesize them as single-phase solid solution and such thermodynamic, elastic properties, and high temperature behavior of wurtzite Ti1-xAlxN is unknown. Here, we investigated the high temperature decomposition behavior of wurtzite Ti1-xAlxN films using experimental methods combined with first-principles calculations. We have developed a method to grow single-phase metastable wurtzite Ti1-xAlxN (x = 0.65, 0.75, 085, and 0.95) solid-solution films by cathodic arc deposition using low duty-cycle pulsed substrate-bias voltage. We report the full elasticity tensor for wurtzite Ti1-xAlxN as a function of Al content and predict a phase diagram including a miscibility gap and spinodals for both cubic and wurtzite Ti1-xAlxN. Complementary high-resolution scanning transmission electron microscopy and chemical mapping demonstrate decomposition of the films after high temperature annealing (950 degrees C), which resulted in nanoscale chemical compositional modulations containing Ti-rich and Al-rich regions with coherent or semicoherent interfaces. This spinodal decomposition of the wurtzite film causes age hardening of 1-2 GPa.

  • 38.
    Salamania, Janella
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Calamba Kwick, Katherine
    Sandvik Coromant AB, Stockholm, Sweden.
    Sangiovanni, Davide Giuseppe
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Tasnadi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Abrikosov, Igor A.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Rogström, Lina
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Johnson, Lars
    Sandvik Coromant AB, Stockholm, Sweden.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    High-resolution STEM investigation of the role of dislocations during decomposition of Ti1-xAlxNy2023Ingår i: Scripta Materialia, ISSN 1359-6462, E-ISSN 1872-8456, Vol. 229, artikel-id 115366Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The defect structures forming during high-temperature decomposition of Ti1-xAlxNy films were investigated through high-resolution scanning transmission electron microscopy. After annealing to 950 °C, misfit edge dislocations a/6〈112〉{111} partial dislocations permeate the interface between TiN-rich and AlN-rich domains to accommodate lattice misfits during spinodal decomposition. The stacking fault energy associated with the partial dislocations decreases with increasing Al content, which facilitates the coherent cubic to wurtzite structure transition of AlN-rich domains. The wurtzite AlN-rich structure is recovered when every third cubic {111} plane is shifted by along the [211] direction. After annealing to 1100 °C, a temperature where coarsening dominates the microstructure evolution, we observe intersections of stacking faults, which form sessile locks at the interface of the TiN- and AlN-rich domains. These observed defect structures facilitate the formation of semicoherent interfaces and contribute to hardening in Ti1-xAlxNy.

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  • 39.
    Salamania, Janella
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Sangiovanni, Davide Giuseppe
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Kraych, A.
    The Interdisciplinary Centre for Advanced Materials Simulation (ICAMS), Ruhr-Universität Bochum, Bochum, Germany.
    Calamba Kwick, K.M.
    Sandvik Coromant AB, Stockholm, Sweden.
    Schramm, I.C.
    Sandvik Coromant AB, Stockholm, Sweden.
    Johnson, L.J.S.
    Sandvik Coromant AB, Stockholm, Sweden.
    Boyd, Robert
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Plasma och ytbeläggningsfysik. Linköpings universitet, Tekniska fakulteten.
    Bakhit, Babak
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Hsu, Tun-Wei
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Mrovec, M.
    The Interdisciplinary Centre for Advanced Materials Simulation (ICAMS), Ruhr-Universität Bochum, Bochum, Germany.
    Rogström, Lina
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Tasnadi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Abrikosov, Igor A.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Elucidating dislocation core structures in titanium nitride through high-resolution imaging and atomistic simulations2022Ingår i: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 224, artikel-id 111327Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Although titanium nitride (TiN) is among the most extensively studied and thoroughly characterizedthin-film ceramic materials, detailed knowledge of relevant dislocation core structures is lacking. Byhigh-resolution scanning transmission electron microscopy (STEM) of epitaxial single crystal (001)-oriented TiN films, we identify different dislocation types and their core structures. These include, besidesthe expected primary a/2{110}h110i dislocation, Shockley partial dislocations a/6{111}h112i and sessileLomer edge dislocations a/2{100}h011i. Density-functional theory and classical interatomic potentialsimulations complement STEM observations by recovering the atomic structure of the different disloca-tion types, estimating Peierls stresses, and providing insights on the chemical bonding nature at the core.The generated models of the dislocation cores suggest locally enhanced metal–metal bonding, weakenedTi-N bonds, and N vacancy-pinning that effectively reduces the mobilities of {110}h110i and {111}h112idislocations. Our findings underscore that the presence of different dislocation types and their effects onchemical bonding should be considered in the design and interpretations of nanoscale and macroscopicproperties of TiN.

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  • 40.
    Sangiovanni, Davide
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Kraych, Antoine
    Ruhr Univ Bochum, Germany.
    Mrovec, Matous
    Ruhr Univ Bochum, Germany.
    Salamania, Janella
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Tasnadi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Descriptor for slip-induced crack blunting in refractory ceramics2023Ingår i: Physical Review Materials, E-ISSN 2475-9953, Vol. 7, nr 10, artikel-id 103601Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Understanding the competition between brittleness and plasticity in refractory ceramics is of importance for aiding design of hard materials with enhanced fracture resistance. Inspired by experimental observations of crack shielding due to dislocation activity in TiN ceramics [Kumar et al., Int. J. Plast. 27, 739 (2011)], we carry out comprehensive atomistic investigations to identify mechanisms responsible for brittleness and slip-induced plasticity in Ti-N systems. First, we validate a semiempirical interatomic potential against density-functional theory results of Griffith and Rice stress intensities for cleavage (K-Ic) and dislocation emission (K-Ie) as well as ab initio molecular dynamics mechanical-testing simulations of pristine and defective TiN lattices at temperatures between 300 and 1200 K. The calculated K-Ic and K-Ie values indicate intrinsic brittleness, as K-Ic &lt;&lt; K-Ie. However, KI-controlled molecular statics simulations-which reliably forecast macroscale mechanical properties through nanoscale modeling-reveal that slip plasticity can be promoted by a reduced sharpness of the crack and/or the presence of anion vacancies. Classical molecular dynamics simulations of notched Ti-N supercell models subject to tension provide a qualitative understanding of the competition between brittleness and plasticity at finite temperatures. Although crack growth occurs in most cases, a sufficiently rapid accumulation of shear stress at the notch tip may postpone or prevent fracture via nucleation and emission of dislocations. Furthermore, we show that the probability to observe slip-induced plasticity leading to crack blunting in flawed Ti-N lattices correlates with the ideal tensile/shear strength ratio (I-plasticity(slip)) of pristine Ti-N crystals. We propose that the I-plasticity(slip) descriptor should be considered for ranking the ability of ceramics to blunt cracks via dislocation-mediated plasticity at finite temperatures.

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  • 41.
    Sangiovanni, Davide
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Tasnadi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Harrington, T.
    Univ Calif San Diego, CA 92093 USA.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Vecchio, K. S.
    Univ Calif San Diego, CA 92093 USA.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten. Natl Univ Sci & Technol MISIS, Russia.
    Temperature-dependent elastic properties of binary and multicomponent high-entropy refractory carbides2021Ingår i: Materials & design, ISSN 0264-1275, E-ISSN 1873-4197, Vol. 204, artikel-id 109634Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Available information concerning the elastic moduli of refractory carbides at temperatures (T) of relevance for practical applications is sparse and/or inconsistent. Ab initio molecular dynamics (AIMD) simulations at T = 300, 600, 900, and 1200 K are carried out to determine the temperature-dependences of the elastic constants of rocksalt-structure (B1) TiC, ZrC, HfC, VC, TaC compounds, as well as high-entropy (Ti,Zr,Hf,Ta,W)C and (V,Nb, Ta,Mo,W)C. The second-order elastic constants are calculated by least-square fitting of the analytical expressions of stress/strain relationships to simulation results obtained from three tensile and three shear deformation modes. Sound-velocity measurements are employed to validate AIMD values of bulk, shear, and elastic moduli of single-phase B1 (Ti,Zr,Hf,Ta,W)C and (V,Nb,Ta,Mo,W)C at ambient conditions. In comparison with the predictions of previous ab initio calculations - where the extrapolation of finite-temperature elastic properties accounted for thermal expansion while neglecting intrinsic vibrational effects - AIMD simulations produce a softening of shear elastic moduli with T in closer agreement with experiments. The results show that TaC is the system which exhibits the highest elastic resistances to tensile and shear deformation up to 1200 K, and indicate the (V,Nb,Ta,Mo,W)C system as candidate for applications that require superior toughness at room as well as elevated temperatures. (C) 2021 The Author(s). Published by Elsevier Ltd.

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  • 42.
    Sangiovanni, Davide
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Tasnadi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Petrov, Ivan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. University of Illinois, USA.
    Greene, Joseph E
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. University of Illinois, USA.
    Chirita, Valeriu
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    N and Ti adatom dynamics on stoichiometric polar TiN(111) surfaces2016Ingår i: Surface Science, ISSN 0039-6028, E-ISSN 1879-2758, Vol. 649, s. 72-79Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We use molecular dynamics (MD) based on the modified embedded atom method (MEAM) to determine diffusion coefficients and migration pathways for Ti and N adatoms (Ti-ad and N-ad) on TiN(111). The reliability of the classical model-potential is verified by comparison with density functional theory (DFT) results at 0 K. MD simulations carried out at temperatures between 600 and 1800 K show that both Ti-ad and N-ad favor fcc surface sites and migrate among them by passing through metastable hcp positions. We find that N-ad species are considerably more mobile than Ti-ad on TiN(111); contrary to our previous results on TiN(001). In addition, we show that lattice vibrations at finite temperatures strongly modify the potential energy landscape and result in smaller adatom migration energies, E-a = 1.03 for Ti-ad and 0.61 eV for N-ad, compared to 0 K values E-aOK = 1.55 (Ti-ad) and 0.79 eV (N-ad). We also demonstrate that the inclusion of dipole corrections, neglected in previous DFT calculations, is necessary in order to obtain the correct formation energies for polar surfaces such as TiN(111). (C) 2016 Elsevier B.V. All rights reserved.

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  • 43.
    Sangiovanni, Davide
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten. Ruhr Univ Bochum, Germany.
    Tasnadi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Johnson, L. J. S.
    Sandvik Coromant, Sweden.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Strength, transformation toughening, and fracture dynamics of rocksalt-structure Ti1-xAlxN (0 <= x <= 0.75) alloys2020Ingår i: Physical Review Materials, E-ISSN 2475-9953, Vol. 4, nr 3, artikel-id 033605Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Ab initio-calculated ideal strength and toughness describe the upper limits for mechanical properties attainable in real systems and can, therefore, be used in selection criteria for materials design. We employ density-functional ab initio molecular dynamics (AIMD) to investigate the mechanical properties of defect-free rocksalt-structure (B1) TiN and B1 Ti1-xAlxN (x = 0.25, 0.5, 0.75) solid solutions subject to [001], [110], and [111] tensile deformation at room temperature. We determine the alloys ideal strength and toughness, elastic responses, and ability to plastically deform up to fracture as a function of the Al content. Overall, TiN exhibits greater ideal moduli of resilience and tensile strengths than (Ti,Al)N solid solutions. Nevertheless, AIMD modeling shows that, irrespective of the strain direction, the binary compound systematically fractures by brittle cleavage at its yield point. The simulations also indicate that Ti0.5Al0.5N and Ti0.25Al0.75N solid solutions are inherently more resistant to fracture and possess much greater toughness than TiN due to the activation of local structural transformations (primarily of B1 -amp;gt; wurtzite type) beyond the elastic-response regime. In sharp contrast, (Ti,Al)N alloys with 25% Al exhibit similar brittleness as TiN. The results of this work are examples of the limitations of elasticity-based criteria for prediction of strength, brittleness, ductility, and toughness in materials able to undergo phase transitions with loading. Comparing present and previous findings, we suggest a general principle for design of hard ceramic solid solutions that are thermodynamically inclined to dissipate extreme mechanical stresses via transformation toughening mechanisms.

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  • 44.
    Shapeev, Alexander V
    et al.
    Skolkovo Inst Sci & Technol, Russia.
    Podryabinkin, Evgeny V
    Skolkovo Inst Sci & Technol, Russia.
    Gubaev, Konstantin
    Skolkovo Inst Sci & Technol, Russia.
    Tasnadi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten. NUST MISIS, Russia.
    Elinvar effect in beta-Ti simulated by on-the-fly trained moment tensor potential2020Ingår i: New Journal of Physics, E-ISSN 1367-2630, Vol. 22, nr 11, artikel-id 113005Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    A combination of quantum mechanics calculations with machine learning techniques can lead to a paradigm shift in our ability to predict materials properties from first principles. Here we show that on-the-fly training of an interatomic potential described through moment tensors provides the same accuracy as state-of-the-art ab initio molecular dynamics in predicting high-temperature elastic properties of materials with two orders of magnitude less computational effort. Using the technique, we investigate high-temperature bcc phase of titanium and predict very weak, Elinvar, temperature dependence of its elastic moduli, similar to the behavior of the so-called GUM Ti-based alloys (Sato et al 2003 Science 300 464). Given the fact that GUM alloys have complex chemical compositions and operate at room temperature, Elinvar properties of elemental bcc-Ti observed in the wide temperature interval 1100-1700 K is unique.

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  • 45.
    Shu, Rui
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Zhang, Xiaofu
    National Key Laboratory of Materials for Integrated Circuits Shanghai Institute of Microsystem and Information Technology Chinese Academy of Sciences, China.
    Tasnadi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Olovsson, Weine
    Linköpings universitet, Tekniska fakulteten. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik.
    Gangaprasad Rao, Smita
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Greczynski, Grzegorz
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Le Febvrier, Arnaud
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Magnuson, Martin
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Eklund, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Stoichiometry Effects on the Chemical Ordering and Superconducting Properties in TiZrTaNbNx Refractory High Entropy Nitrides2023Ingår i: Annalen der Physik, ISSN 0003-3804, E-ISSN 1521-3889, artikel-id 2300470Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    High-entropy materials, an exciting new class of structural materials involvingfive or more elements, are emerging as unexplored ground forsuperconductors. Here, the effects of nitrogen stoichiometry are investigatedon local chemical structure of TiZrNbTa-based thin films by variousX-ray-based techniques. Lattice distortion and short-range order of a set ofTiZrNbTaNxsamples, including bond lengths of different atomic pairs andcoordination numbers of substituting atoms are quantitatively studied. Themaximum superconducting transition temperature Tcis found at 10 K for anear-stoichiometric (TiZrNbTa)N1.08film, which is>8 K measured for ametallic TiZrNbTa film. The underlying electronic structure and chemicalbonding in these high entropy nitrides thus influence the superconductingmacroscopic properties.

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  • 46.
    Shulumba, Nina
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten. University of Saarland, Germany.
    Hellman, Olle
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten. Division of Engineering and Applied Science, California Institute of Technology, Pasadena, California, USA.
    Rogström, Lina
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Raza, Zamaan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Tasnádi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten. Materials Modeling and Development Laboratory, NUST “MISIS”, Moscow, Russia / LACOMAS Laboratory, Tomsk State University, Tomsk, Russia.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Temperature-dependent elastic properties of Ti1−xAlxN alloys2015Ingår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 107, nr 23Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Ti1−xAlxN is a technologically important alloy that undergoes a process of high temperature age-hardening that is strongly influenced by its elastic properties. We have performed first principles calculations of the elastic constants and anisotropy using the newly developed symmetry imposed force constant temperature dependent effective potential method, that include lattice vibrations and therefore the effects of temperature, including thermal expansion and intrinsic anharmonicity. These are compared with in situ high temperature x-ray diffraction measurements of the lattice parameter. We show that anharmonic effects are crucial to the recovery of finite temperature elasticity. The effects of thermal expansion and intrinsic anharmonicity on the elastic constants are of the same order, and cannot be considered separately. Furthermore, the effect of thermal expansion on elastic constants is such that the volume change induced by zero point motion has a significant effect. For TiAlN, the elastic constants soften non-uniformly with temperature: C11 decreases substantially when the temperature increases for all compositions, resulting in an increased anisotropy. These findings suggest that an increased Al content and annealing at higher temperatures will result in a harder alloy.

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  • 47.
    Skripnyak, Natalia
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Tasnadi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Simak, Sergey
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Ponomareva, A. V.
    Natl Univ Sci & Technol MISIS, Russia.
    Lofstrand, J.
    Uppsala Univ, Sweden.
    Berastegui, P.
    Uppsala Univ, Sweden.
    Jansson, U.
    Uppsala Univ, Sweden.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska fakulteten.
    Achieving low elastic moduli of bcc Ti-V alloys in vicinity of mechanical instability2020Ingår i: AIP Advances, E-ISSN 2158-3226, Vol. 10, nr 10, artikel-id 105322Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Body centered cubic (bcc) Ti-based alloys are of interest for multiple technological applications ranging from aerospace technology to biomedicine. However, these alloys are usually unstable at low temperatures. Indeed, the calculated elastic modulus C of bcc Ti-V alloys with low V concentrations is negative at 0 K temperature, indicating their mechanical instability. Here, we investigate elastic moduli of the Ti-V system in the vicinity of mechanical instability theoretically and experimentally. Our calculations predict that mechanical stabilization of bcc Ti-V alloys, which is governed by the hardening of C , is possible at as low V concentration as 18 at.%. We synthesize single-phase bcc alloys with as little as 22 at.% of V with low values of Youngs modulus. Moreover, we predict strong concentration dependence of anisotropy of Youngs modulus in these alloys that can also be used in tuning the alloy composition to design materials for specific applications.

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  • 48.
    Steneteg, Peter
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Hellman, Olle
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Vekilova, Olga
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Shulumba, Nina
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Tasnádi, Ferenc
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Temperature dependence of TiN elastic constants from ab initio molecular dynamics simulations2013Ingår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 87, nr 9Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Elastic properties of cubic TiN are studied theoretically in a wide temperature interval. First-principles simulations are based on ab initio molecular dynamics (AIMD). Computational efficiency of the method is greatly enhanced by a careful preparation of the initial state of the simulation cell that minimizes or completely removes a need for equilibration and therefore allows for parallel AIMD calculations. Elastic constants C11, C12, and C44 are calculated. A strong dependence on the temperature is predicted, with C11 decreasing by more than 29% at 1800 K as compared to its value obtained at T=0 K. Furthermore, we analyze the effect of temperature on the elastic properties of polycrystalline TiN in terms of the bulk and shear moduli, the Young's modulus and Poisson ratio. We construct sound velocity anisotropy maps, investigate the temperature dependence of elastic anisotropy of TiN, and observe that the material becomes substantially more isotropic at high temperatures. Our results unambiguously demonstrate the importance of taking into account finite temperature effects in theoretical calculations of elastic properties of materials intended for high-temperature applications.

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  • 49.
    Tasnadi, Ferenc
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Katardjiev , Ilia
    Uppsala University.
    Significant configurational dependence of the electromechanical coupling constant of B0.125Al0.875N2009Ingår i: APPLIED PHYSICS LETTERS, ISSN 0003-6951 , Vol. 94, nr 15Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Currently, AlN is the preferred material in electroacoustic applications but modern applications necessitate the synthesis of materials with a range of electroacoustic properties. Among the promising candidates are the wurtzite Boron-containing AlN alloys. In here we study theoretically some of the material properties of wurtzite B0.125Al0.875N. The results indicate that wurtzite B0.125Al0.875N exhibits a strong configurational dependence of the electromechanical coupling constant. It is further shown that the lattice parameters as well as the stiffness constants are less sensitive of the atomic configuration and comply well with the Vegards rule.

  • 50.
    Tasnadi, Ferenc
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Alling, Björn
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Höglund, Carina
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Wingqvist, Gunilla
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Abrikosov, Igor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Origin of the Anomalous Piezoelectric Response in Wurtzite ScxAl1-xN Alloys2010Ingår i: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 104, nr 13, s. 137601-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The origin of the anomalous, 400% increase of the piezoelectric coefficient in ScxAl1-xN alloys is revealed. Quantum mechanical calculations show that the effect is intrinsic. It comes from a strong change in the response of the internal atomic coordinates to strain and pronounced softening of C-33 elastic constant. The underlying mechanism is the flattening of the energy landscape due to a competition between the parent wurtzite and the so far experimentally unknown hexagonal phases of the alloy. Our observation provides a route for the design of materials with high piezoelectric response.

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