Browsing Kjemisk institutt by Author "Fjellvåg, Helmer"

Now showing items 21-40 of 68

  • Effect of Subcycle Arrangement on Direct Epitaxy in ALD of LaNiO3 
    Sønsteby, Henrik Hovde; Skaar, Erik; Fjellvåg, Helmer; Nilsen, Ola (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
    Monolithic device integration of crystalline complex oxide thin films can open for smarter and more sustainable devices in electronics and energy technology. However, the facile integration of such compounds has so far ...
  • Effect ofl larger pore size on the sorption properties of isoreticular metal–organic frameworks with high number of open metal sites 
    Dietzel, Pascal D.C.; Georgiev, Peter A.; Frøseth, Morten; Johnsen, Rune E.; Fjellvåg, Helmer; Blom, Richard (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)
    Four isostructural CPO‐54‐M metal‐organic frameworks based on the larger organic linker 1,5‐dihydroxynaphthalene‐2,6‐dicarboxylic acid and divalent cations (M=Mn, Mg, Ni, Co) are shown to be isoreticular to the CPO‐27 ...
  • Effects of Ga Substitution on the Local Structure of Na2Zn2TeO6 
    Hempel, Frida Sveen; Bianchini, Federico; Arstad, Bjørnar; Fjellvåg, Helmer (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2022)
    In the work presented here, we prepared Ga-substituted NZTO (Na2–xZn2–xGaxTeO6, x = 0.00, 0.05, 0.10, 0.15, 0.20) layered materials with a soft chemical, citric acid-based synthesis method and characterized these by means ...
  • Electronic structure and optical properties of ZnSiO3 and Zn2SiO4 
    Karazhanov, Smagul; Ravindran, Ponniah; Fjellvåg, Helmer; Svensson, Bengt Gunnar (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2009)
    The electronic structure and optical properties of orthorhombic, monoclinic, and rhombohedral (corundum type) modifications of ZnSiO3, and of rhombohedral, tetragonal, and cubic (spinel type) modifications of Zn2SiO4 have ...
  • Enhancing giant magnetocaloric effect near room temperature by inducing magnetostructural coupling in Cu-doped MnCoGe 
    Pal, Santosh Kumar; Frommen, Christoph; Kumar, Susmit; Hauback, Bjørn; Fjellvåg, Helmer; Helgesen, Geir (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)
    High performance magnetocaloric materials are crucial to realize the energy efficient and environment friendly magnetic cooling/refrigeration technology. We have designed Mn1-xCuxCoGe compounds possessing a giant magnetocaloric ...
  • Exotic Compositional Ordering in Manganese–Nickel–Arsenic (Mn-Ni-As) Intermetallics 
    Gonano, Bruno Raymond Gino; Fjellvåg, Øystein; Steciuk, Gwladys; Saha, Dipankar; Pelloquin, Denis; Fjellvåg, Helmer (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)
    In this work we benefited from recent advances in tools for crystal‐structure analysis that enabled us to describe an exotic nanoscale phenomenon in structural chemistry. The Mn0.60Ni0.40As sample of the Mn1−xNixAs solid ...
  • Exploring V-Fe-Co-Ni-Al and V-Fe-Co-Ni-Cu high entropy alloys for magnetocaloric applications 
    Eggert, Bruno G. F.; Delczeg-Czirjak, Erna K.; Maccari, Fernando; Kumar, Susmit; Gutfleisch, Oliver; Fjellvåg, Helmer; Hauback, Bjørn Christian; Frommen, Christoph (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2022)
    A series of V1−x-Fe-Co-Ni-Al1+x and V1−x-Fe-Co-Ni-Cu1+x high entropy alloys with varying compositions (0 ≤ x ≤ 0.75) has been investigated for magnetocaloric applications. Compositions were selected according to established ...
  • First principle studies on electronic and thermoelectric properties of Fe2TiSn based multinary Heusler alloys 
    Choudhary, Mukesh K.; Fjellvåg, Helmer; Ponniah, Ravindran (Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2023)
  • First-Principles Insights into the Relative Stability and Physical and Chemical Properties of MoSe2 
    Banu S, Lathifa; Veerapandy, Vasu; Fjellvåg, Helmer; Ponniah, Vajeeston (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
    A fascinating transition-metal dichalcogenide (TMDC) compound, MoSe2, has attracted a lot of interest in electrochemical, photocatalytic, and optoelectronic systems. However, detailed studies on the structural stability ...
  • First-principles study of structural stability, dynamical and mechanical properties of Li2FeSiO4 polymorphs 
    Vajeeston, Ponniah; Fjellvåg, Helmer (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2017)
    Li2FeSiO4 is an important alternative cathode for next generation Li-ion batteries due to its high theoretical capacity (330 mA h g−1). However, its development has faced significant challenges arising from structural ...
  • First-Principles Study of the Structural Stability and Dynamic Properties of Li2MSiO4 (M = Mn, Co, Ni) Polymorphs 
    Vajeeston, Ponniah; Bianchini, Federico; Fjellvåg, Helmer (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2019)
    In recent years, the scientific community has shown an increasing interest in regards to the investigation of novel materials for the intercalation of lithium atoms, suitable for application as cathodes in the new generations ...
  • First-principles study of the structural stability and electrochemical properties of Na2MSiO4 (M = Mn, Fe, Co and Ni) polymorphs 
    Bianchini, Federico; Fjellvåg, Helmer; Vajeeston, Ponniah (Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2017)
    Sodium orthosilicates Na2MSiO4 (M = Mn, Fe, Co and Ni) have attracted much attention due to the possibility of exchanging two electrons per formula unit. They are also found to exhibit great structural stability due to a ...
  • A foundation for complex oxide electronics -low temperature perovskite epitaxy 
    Sønsteby, Henrik H.; Skaar, Erik; Fjellvåg, Øystein; Bratvold, Jon E.; Fjellvåg, Helmer; Nilsen, Ola (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)
    As traditional silicon technology is moving fast towards its fundamental limits, all-oxide electronics is emerging as a challenger offering principally different electronic behavior and switching mechanisms. This technology ...
  • From Colloidal Monodisperse Nickel Nanoparticles to Well-Defined Ni/Al2O3 Model Catalysts 
    Zacharaki, Eirini; Beato, Pablo; Tiruvalam, Ramchandra R; Andersson, Klas J.; Fjellvåg, Helmer; Sjåstad, Anja Olafsen (Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2017)
    In the past few decades, advances in colloidal nanoparticle synthesis have created new possibilities for the preparation of supported model catalysts. However, effective removal of surfactants is a prerequisite to evaluate ...
  • Insights into Crystal Structure and Diffusion of Biphasic Na2Zn2TeO6 
    Li, Xinyu; Bianchini, Federico; Wind, Julia; Pettersen, Christine; Vajeeston, Ponniah; Wragg, David; Fjellvåg, Helmer (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)
    The layered oxide Na2Zn2TeO6 is a fast Na+ ion conductor and a suitable candidate for application as a solid-state electrolyte. We present a detailed study on how synthesis temperature and Na-content affect the crystal ...
  • Intense NIR emission in YVO4:Yb3+ thin films by atomic layer deposition 
    Getz, Michael; Hansen, Per-Anders Stensby; Fjellvåg, Øystein Slagtern; Ahmed, Mohammed Amin Karim; Fjellvåg, Helmer; Nilsen, Ola (Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2017)
    We demonstrate controlled deposition by atomic layer deposition of YVO4:Yb3+ thin films exhibiting an intense NIR emission under UV excitation after post-deposition annealing at 1000 °C. The samples are deposited using the ...
  • Ionic conductivity in LixTaOy thin films grown by Atomic Layer Deposition (ALD) 
    Hu, Yang; Miikkulainen, Ville; Mizohata, Kenichiro; Norby, Truls Eivind; Nilsen, Ola; Fjellvåg, Helmer (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)
    The material system Li-Ta-O is a promising candidate for thin-film solid-state electrolytes in Li-ion batteries. In the present study, we have varied the Li content x in LixTaOy thin films grown by atomic layer deposition ...
  • 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 ...
  • Lanthanide substitution in YBa2Cu3O9−d 
    Karen, Pavel; Fjellvåg, Helmer; Braaten, O.; Kjekshus, Arne; Bratsberg, H. (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 1990)
    © 1990 Acta Chemica Scandinavica
  • Lanthanum substitution in YBa2Cu3O9−d 
    Andresen, A.F.; Fjellvåg, Helmer; Karen, Pavel; Kjekshus, Arne (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 1988)
    This research was originally published in Zeitschrift für Kristallographie - New Crystal Structures. © 1988 De Gruyter