Browsing Det matematisk-naturvitenskapelige fakultet by Author "Løvvik, Ole Martin"

Now showing items 1-13 of 13

  • Application of machine learning-based selective sampling to determine BaZrO3 grain boundary structures 
    Bondevik, Tarjei; Kuwabara, Akihide; Løvvik, Ole Martin (Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2019)
    A selective sampling procedure is applied to reduce the number of density functional theory calculations needed to find energetically favorable grain boundary structures. The procedure is based on a machine learning algorithm ...
  • Attaining Low Lattice Thermal Conductivity in Half-Heusler Sublattice Solid Solutions: Which Substitution Site Is Most Effective? 
    Tranås, Rasmus André; Løvvik, Ole Martin; Berland, Kristian (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2022)
    Low thermal conductivity is an important materials property for thermoelectricity. The lattice thermal conductivity (LTC) can be reduced by introducing sublattice disorder through partial isovalent substitution. Yet, ...
  • Calculation of the anisotropic coefficients of thermal expansion: A first-principles approach 
    Pike, Nicholas; Løvvik, Ole Martin (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2019)
    Predictions of the anisotropic coefficients of thermal expansion are needed to not only compare to experimental measurement, but also as input for macroscopic modeling of devices which operate over a large temperature ...
  • Controlling the Electrical Properties of Reactively Sputtered High Entropy Alloy CrFeNiCoCu Films 
    Mayandi, Jeyanthinath; Finstad, Terje Gunnar; Stange, Marit Synnøve Sæverud; Vasquez, Geraldo Cristian; Sunding, Martin Fleissner; Løvvik, Ole Martin; Diplas, Spyridon; Almeida Carvalho, Patricia (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2022)
    Oxide-containing films were made by reactively sputtering a high-entropy alloy target of CrFeCoNiCu. We report on a wide range of changes to the electrical properties made by different heat treatments in oxidizing and ...
  • High entropy alloy CrFeNiCoCu sputter deposited films: Structure, electrical properties, and oxidation 
    Mayandi, Jeyanthinath; Schrade, Matthias; Vajeeston, Ponniah; Stange, Marit Synnøve Sæverud; Lind, Anna Maria; Sunding, Martin Fleissner; Deuermeier, Jonas; Fortunato, Elvira; Løvvik, Ole Martin; Ulyashin, Alexander; Diplas, Spyridon; Almeida Carvalho, Patricia; Finstad, Terje Gunnar (Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2022)
    High entropy alloy (HEA) films of CrFeCoNiCu were deposited by sputtering. Their structure was characterized and their electric transport properties were studied by temperature-dependent Hall and Seebeck measurements. The ...
  • Investigation of the electrostatic potential of a grain boundary in Y-substituted BaZrO3 using inline electron holography 
    Bondevik, Tarjei; Ness, Heine H.; Bazioti, Kalliopi; Norby, Truls Eivind; Løvvik, Ole Martin; Koch, Christoph T.; Prytz, Øystein (Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2019)
    We apply inline electron holography to investigate the electrostatic potential across an individual BaZr0.9Y0.1O3 grain boundary. With holography, we measure a grain boundary potential of −1.3 V. Electron energy loss ...
  • Jahn-Teller active fluoroperovskites ACrF3 (A=Na+, K+): Magnetic and thermo-optical properties 
    Bernal, Fabian Leonardo Martinez; Lundvall, Fredrik; Kumar, Susmit; Hansen, Per-Anders S.; Wragg, David S.; Fjellvåg, Helmer; Løvvik, Ole Martin (Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2021)
    Chromium (II) fluoroperovskites A CrF 3 ( A = Na + , K + ) are strongly correlated Jahn-Teller active materials at low temperatures. In this paper, we examine the role that the A -site ion plays in this family of ...
  • Lattice thermal conductivity of half-Heuslers with density functional theory and machine learning: Enhancing predictivity by active sampling with principal component analysis 
    Tranås, Rasmus André; Løvvik, Ole Martin; Tomic, Oliver; Berland, Kristian (Journal article / Tidsskriftartikkel / SubmittedVersion, 2021)
    Low lattice thermal conductivity is essential for high thermoelectric performance of a material. Lattice thermal conductivity is often computed using density functional theory (DFT), typically at a high computational cost. ...
  • New structure and insight on the phase transition within the Cu-Pd-Sn system with 25 at. % Sn 
    Amundsen, Monika; Pike, Nicholas; Løvvik, Ole Martin; Almeida Carvalho, Patricia; Gunnæs, Anette Eleonora (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2022)
    The Cu-Pd-Sn material system has a (Cu, Pd) 3 Sn phase region that shows an interesting and unexplored marten- sitic phase transformation. Literature on this system is limited and the description of the phases present is ...
  • Probing the structural evolution and its impact on magnetic properties of FeCoNi(AlMn)x high-entropy alloy at the nanoscale 
    Bazioti, Kalliopi; Løvvik, Ole Martin; Poulia, Anthoula; Almeida Carvalho, Patricia; S. Azar, Amin; Mikheenko, Pavlo; Diplas, Spyridon; Gunnæs, Anette Eleonora (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2022)
    We report the first nanoscale investigation of FeCoNi(AlMn)x high-entropy alloys (HEAs) processed by laser metal deposition. The structural evolution of the alloy upon chemical composition variation (0.2 ≤ x ≤ 1.5) was ...
  • Structural and magnetic characterization of the elusive Jahn-Teller active NaCrF3 
    Bernal, Fabian Leonardo Martinez; Sottmann, Jonas; Wragg, David; Fjellvåg, Helmer; Fjellvåg, Øystein; Drathen, Christina; Slawinski, Wojciech Andrzej; Løvvik, Ole Martin (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)
    We report on the structural and magnetic properties of the elusive Jahn-Teller active compound NaCrF3, for first time synthesized in large quantities allowing detailed characterization. The crystal structure of NaCrF3 is ...
  • Thermoelectric transport trends in group 4 half-Heusler alloys 
    Berland, Kristian; Shulumba, Nina; Hellman, Olle; Persson, Clas; Løvvik, Ole Martin (Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2019)
    The thermoelectric properties of 54 different group 4 half-Heusler (HH) alloys have been studied from first principles. Electronic transport was studied with density functional theory using hybrid functionals facilitated ...
  • Thin films made by reactive sputtering of high entropy alloy FeCoNiCuGe: Optical, electrical and structural properties 
    Mayandi, Jeyanthinath; Finstad, Terje Gunnar; Dahl, Øyvind; Ponniah, Vajeeston; Schrade, Matthias; Løvvik, Ole Martin; Diplas, Spyridon; Almeida Carvalho, Patricia (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2022)
    Films were reactively sputtered from a high entropy alloy (HEA) FeCoNiCuGe target in an Ar/O2 plasma. The case of zero O2 gas flow yielded HEA films of FeCoNiCuGe. These as-deposited HEA films have a face centered cubic ...