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• Gauthier, Nicolas; Sibille, Romain; Pomjakushin, Vladimir; Fjellvåg, Øystein Slagtern; Fraser, James & Desmarais, Mathieu [Vis alle 8 forfattere av denne artikkelen] (2024). Magnetic structure of Ce3TiBi5 and its relation to current-induced magnetization. Physical review B (PRB). ISSN 2469-9950. 109. doi: 10.1103/PhysRevB.109.L140405.
• Huangfu, Shangxiong; Austin, Alexandra C.; Guguchia, Zurab; Fjellvåg, Øystein Slagtern; Knorpp, Amy J. & Luetkens, H. [Vis alle 8 forfattere av denne artikkelen] (2023). Tuneable Short-Range Antiferromagnetic Correlation in Fe-Containing Entropy Stabilized Oxides. Inorganic Chemistry. ISSN 0020-1669. 63(1), s. 247–255. doi: 10.1021/acs.inorgchem.3c03028.
• Thøgersen, Rasmus Vester; Fjellvåg, Asbjørn Slagtern; Fjellvåg, Øystein Slagtern & Fjellvåg, Helmer (2023). Structural and magnetic properties of antifluorite-type Li5+xFe1−xCoxO4. Zeitschrift für Anorganische und Allgemeines Chemie. ISSN 0044-2313. 649(22). doi: 10.1002/zaac.202300146. Fulltekst i vitenarkiv
• Sannes, Johnny Andreas; Gonano, Bruno; Fjellvåg, Øystein Slagtern; Kumar, Susmit; Nilsen, Ola & Valldor, Björn Martin (2023). X-ray and Neutron Diffraction Studies of SrTe<inf>2</inf>FeO<inf>6</inf>Cl, an Oxide Chloride with Rare Anion Ordering. Inorganic Chemistry. ISSN 0020-1669. 62(32), s. 13081–13088. doi: 10.1021/acs.inorgchem.3c01951. Fulltekst i vitenarkiv
• Chakravarty, Shruti; Fjellvåg, Øystein Slagtern; Bhattacharyya, Arpan; Keller, Lukas & Nair, Sunil (2023). Disorder-driven cluster glass state in a geometrically frustrated hexagonal perovskite. Physical review B (PRB). ISSN 2469-9950. 107(13), s. 1–12. doi: 10.1103/PhysRevB.107.134414.
• Sottmann, Jonas; Ruud, Amund; Fjellvåg, Øystein; Vaughan, Gavin B. M.; Di Michel, Marco & Fjellvåg, Helmer [Vis alle 9 forfattere av denne artikkelen] (2022). 5D total scattering computed tomography reveals the full reaction mechanism of a bismuth vanadate lithium ion battery anode. Physical Chemistry, Chemical Physics - PCCP. ISSN 1463-9076. 24(44), s. 27075–27085. doi: 10.1039/d2cp03892g. Fulltekst i vitenarkiv
• Biswas, Banani; Michel, Veronica F.; Fjellvåg, Øystein; Bimashofer, Gesara; Döbeli, Max & Jambor, Michal [Vis alle 15 forfattere av denne artikkelen] (2022). Role of Dy on the magnetic properties of orthorhombic DyFeO3. PHYSICAL REVIEW MATERIALS. ISSN 2475-9953. 6(7). doi: 10.1103/PhysRevMaterials.6.074401.
• Periyasamy, Manimuthu; Patra, Lokanath; Fjellvåg, Øystein; Ravindran, Ponniah; Sørby, Magnus Helgerud & Kumar, Susmit [Vis alle 8 forfattere av denne artikkelen] (2021). Effect of electron doping on the crystal structure and physical properties of an n = 3 Ruddlesden-Popper compound La4Ni3O10. ACS Applied Electronic Materials. ISSN 2637-6113. 3(6), s. 2671–2684. doi: 10.1021/acsaelm.1c00270. Fulltekst i vitenarkiv
• Ek, Gustav; Fjellvåg, Øystein; Vajeeston, Ponniah; Armstrong, Jeff; Sahlberg, Martin & Häussermann, Ulrich (2021). Vibrational properties of High Entropy Alloy based metal hydrides probed by inelastic neutron scattering. Journal of Alloys and Compounds. ISSN 0925-8388. 877, s. 1–7. doi: 10.1016/j.jallcom.2021.160320. Fulltekst i vitenarkiv
• Gonano, Bruno Raymond Gino; Fjellvåg, Øystein; Steciuk, Gwladys; Guillou, Francois; Saha, Dipankar & Pelloquin, Denis [Vis alle 7 forfattere av denne artikkelen] (2021). Tuning the Magnetically Segregated Nanolayering in Mn–Ni–As Intermetallics. Chemistry of Materials. ISSN 0897-4756. 33(8), s. 3002–3010. doi: 10.1021/acs.chemmater.1c00760. Fulltekst i vitenarkiv
• Fjellvåg, Asbjørn Slagtern; Fjellvåg, Øystein; Breard, Y. & Sjåstad, Anja Olafsen (2021). Structural disorder and antiferromagnetism in LaNi1–xPtxO3. Journal of Solid State Chemistry. ISSN 0022-4596. 229. doi: 10.1016/j.jssc.2021.122181. Fulltekst i vitenarkiv
• Fjellvåg, Asbjørn Slagtern; Fjellvåg, Øystein; Kumar, Susmit; Ruud, Amund & Sjåstad, Anja Olafsen (2021). Interplay of valence states and magnetic interactions in the perovskite system LaNi1–xRhxO3. Journal of Solid State Chemistry. ISSN 0022-4596. 298. doi: 10.1016/j.jssc.2021.122124. Fulltekst i vitenarkiv Vis sammendrag

  We report on the structural, magnetic and electronic properties of Rh substituted LaNiO3, LaNi1–xRhxO3 (0 ​≤ ​x ​≤ ​1). Increased Rh contents are associated with increased structural distortion, and we observe a phase transformation and an immiscibility gap between 0.15 ​≤ ​x ​≤ ​0.25, separating the R-3c and Pnma perovskite structure regimes. Structural evaluation by synchrotron X-ray diffraction, X-ray absorption spectroscopy and DC magnetic measurements suggest variations in oxidation state for the B-site cations, with Ni(II)/Rh(IV), in addition to Rh(III), dominating for high Rh-contents. Although ordering of Ni(II)/Rh(IV) is possible, no B-site ordering between Ni and Rh is observed for any composition. A metal-to-insulator transition occurs upon Rh-substitution, correlating with the structural transition. DC- and AC magnetic measurements reveal that several of the compositions are magnetically frustrated with both antiferro- and ferromagnetic behaviour at low temperatures. The antiferromagnetic interactions are dominating, while the ferromagnetic interactions increase with increasing Rh-content, to a maximum at x ​= ​0.80 and x ​= ​0.90 in LaNi1–xRhxO3. The mixed valence states are assumed to contribute with a ferromagnetic super-exchange interaction between Ni(II) and Rh(IV).

• Nygård, Magnus Moe; Fjellvåg, Øystein; Sørby, Magnus Helgerud; Sakaki, Kouji; Ikeda, Kazutaka & Armstrong, Jeff [Vis alle 12 forfattere av denne artikkelen] (2021). The average and local structure of TiVCrNbDx (x = 0, 2.2, 8) from total scattering and neutron spectroscopy. Acta Materialia. ISSN 1359-6454. 205, s. 1–15. doi: 10.1016/j.actamat.2020.116496. Fulltekst i vitenarkiv
• Bernal, Fabian Leonardo Martinez; Gonano, Bruno Raymond Gino; Lundvall, Fredrik; Wragg, David; Fjellvåg, Helmer & Veillon, Fabien [Vis alle 8 forfattere av denne artikkelen] (2020). Canted antiferromagnetism in high-purity NaFeF3 prepared by a novel wet-chemical synthesis method. PHYSICAL REVIEW MATERIALS. ISSN 2475-9953. 4(11). doi: 10.1103/PhysRevMaterials.4.114412. Fulltekst i vitenarkiv
• Gonano, Bruno Raymond Gino; Fjellvåg, Øystein; Steciuk, Gwladys; Saha, Dipankar; Pelloquin, Denis & Fjellvåg, Helmer (2020). Exotic Compositional Ordering in Manganese–Nickel–Arsenic (Mn-Ni-As) Intermetallics. Angewandte Chemie International Edition. ISSN 1433-7851. 132(50), s. 22568–22573. doi: 10.1002/anie.202006135. Fulltekst i vitenarkiv
• Fjellvåg, Øystein; Ruud, Amund; Sønsteby, Henrik Hovde; Nilsen, Ola & Fjellvåg, Helmer (2020). Crystallization, Phase Stability, and Electrochemical Performance of β-MoO3 Thin Films. Crystal Growth & Design. ISSN 1528-7483. 20(6), s. 3861–3866. doi: 10.1021/acs.cgd.0c00156. Fulltekst i vitenarkiv Vis sammendrag

  Insight into the crystallization process of functional materials deposited as thin films in an amorphous state is essential when phase pure samples of specific polymorphs are sought for utilization of performance aspects or fundamental studies. In this work, we report on controlled crystallization of α- and β-MoO3 polymorphs from amorphous MoO3 thin films produced by atomic layer deposition (ALD). The MoO3 films are amorphous as deposited. Our experiments show that β-MoO3 starts to crystallize from amorphous MoO3 at a surprisingly low temperature of 185 °C, only 20 °C above the adopted ALD deposition temperature. Thin films of the β-MoO3 polymorph start to slowly convert into α-MoO3 at temperatures above 300 °C; however, long holding times are required to obtain phase pure products. High-quality thin film samples (electrodes) were characterized by electrochemical cycling toward lithium, demonstrating that α- and β-MoO3 transfers into the same chemical state during cycling and that amorphous MoO3 undergoes less change upon cycling.

• Sønsteby, Henrik Hovde; Skaar, Erik; Fjellvåg, Øystein; Bratvold, Jon E.; Fjellvåg, Helmer & Nilsen, Ola (2020). A foundation for complex oxide electronics -low temperature perovskite epitaxy. Nature Communications. ISSN 2041-1723. 11(1). doi: 10.1038/s41467-020-16654-2. Fulltekst i vitenarkiv
• Periyasamy, Manimuthu; Fjellvåg, Øystein; Fjellvåg, Helmer & Sjåstad, Anja Olafsen (2020). Coupling of magnetoresistance switching and glassy magnetic state at the metal–insulator transition in Ruddlesden-Popper manganite Ca4Mn3O10. Journal of Magnetism and Magnetic Materials. ISSN 0304-8853. 511, s. 1–8. doi: 10.1016/j.jmmm.2020.166949. Fulltekst i vitenarkiv
• Bernal, Fabian Leonardo Martinez; Sottmann, Jonas; Wragg, David; Fjellvåg, Helmer; Fjellvåg, Øystein & Drathen, Christina [Vis alle 8 forfattere av denne artikkelen] (2020). Structural and magnetic characterization of the elusive Jahn-Teller active NaCrF3. PHYSICAL REVIEW MATERIALS. ISSN 2475-9953. 4(5). doi: 10.1103/PhysRevMaterials.4.054412. Fulltekst i vitenarkiv
• Fjellvåg, Øystein; Krzystyniak, Matthew; Vajeeston, Ponniah; Sjåstad, Anja Olafsen & Armstrong, Jeff (2019). A combined deep inelastic neutron scattering andab initiolattice dynamics study of the hydride anion dynamics and bonding in La2LiHO3 oxyhydride. Journal of Physics Communications. ISSN 2399-6528. 3(10). doi: 10.1088/2399-6528/ab4be6. Fulltekst i vitenarkiv Vis sammendrag

  Kobayashi et al (6279) (Science 2016, 351) reported recently the existence of pure H- conductivity in the oxyhydride La2−x−y Sr x+y LiH1−x+y O3−y , while demonstrating its functionality through a prototype solid-state Ti/La2LiHO3/TiH2 battery. In this study, we probe the atomistic motion of La2LiHO3 obtained by the promising halide salt flux method, via a combination of deep inelastic neutron scattering (DINS) and ab initio lattice dynamics (LD) calculations verified by vibrational inelastic neutron spectroscopy (INS). We successfully describe the measured momentum distributions from DINS via our LD calculations, without observing any diffusion activation over the temperature range reported by Kobayashi et al. This observation is corroborated by model predictions from our LD study, which reveals that the hydride anions remain bound within a 3D-harmonic potential. We conclude that with the current synthesis parameters, the method produces a vacancy free lattice, and that a necessary ingredient for diffusive motion of H- is the presence of a large population of vacancies. Based on the harmonic prediction for the hydrogen kinetic energy, we derive a picture of the evolution of the effective bonding potential for the hydride anions, and link this to the dynamics associated with decomposition of the oxyhydride.

• Kumar, Susmit; Fjellvåg, Øystein; Sjåstad, Anja Olafsen & Fjellvåg, Helmer (2019). Physical properties of Ruddlesden-Popper (n = 3) nickelate: La4Ni3O10. Journal of Magnetism and Magnetic Materials. ISSN 0304-8853. 496. doi: 10.1016/j.jmmm.2019.165915. Fulltekst i vitenarkiv
• Liu, Xin; Bjørheim, Tor Svendsen; Vines, Lasse; Fjellvåg, Øystein; Granerød, Cecilie Skjold & Prytz, Øystein [Vis alle 10 forfattere av denne artikkelen] (2019). Highly Correlated Hydride Ion Tracer Diffusion in SrTiO3–xHx Oxyhydrides. Journal of the American Chemical Society. ISSN 0002-7863. 141(11), s. 4653–4659. doi: 10.1021/jacs.8b12985. Fulltekst i vitenarkiv
• Fjellvåg, Øystein; Øygarden, Vegar; Sørby, Magnus Helgerud & Sjåstad, Anja Olafsen (2019). Crystal structure of LaSr3Fe3O9 and its phase relation with LaSr3Fe3O10. Journal of Solid State Chemistry. ISSN 0022-4596. 275, s. 56–62. doi: 10.1016/j.jssc.2019.03.050. Fulltekst i vitenarkiv Vis sammendrag

  The Ruddlesden-Popper phase LaSr3Fe3O10 and its reduced derivatives with nominal composition LaSr3Fe3O10–x, with 0 < x < 1.21, are described in detail with respect to crystal structure, magnetic order, thermal stability and likely vacancy mechanisms. The crystal structure of the LaSr3Fe3O9 (x = 1) phase is described. The LaSr3Fe3O10-δ phase prevails for x < 0.51, whereas LaSr3Fe3O9±ε prevails for x > 0.85. The phases are separated by a two-phase region 0.51 < x < 0.85. By combined Rietveld refinements of high-resolution powder synchrotron and neutron diffraction, the crystallographic and magnetic structure of LaSr3Fe3O9 is described. LaSr3Fe3O9 takes a layer like RP3 type structure with features of the brownmillerite structure in the triple perovskite type slabs; unit cell dimensions a = 28.7562(13) Å, b = 5.5280(2) Å, c = 5.4583(2) Å, space group Cmcm. LaSr3Fe3O9 is an antiferromagnet with TN > 350 K and with a G-type magnetic structure, magnetic space group PCbcm. Based on unit cell volume considerations, local oxygen vacancy ordering schemes are suggested.

• Fjellvåg, Øystein; Nygård, Kristin Hubred; Vajeeston, Ponniah & Sjåstad, Anja Olafsen (2019). Advances in the LiCl salt flux method and the preparation of phase pure La2−xNdxLiHO3 (0 ≤ x ≤ 2) oxyhydrides. Chemical Communications. ISSN 1359-7345. 55(26), s. 3817–3820. doi: 10.1039/c9cc00920e. Vis sammendrag

  The LiCl salt flux method is an established aid in oxyhydride synthesis. By operating the flux below its melting point, we have obtained phase pure Nd2LiHO3 for the first time. Further, the suitability of the flux method is shown to be dictated by a delicate balance between the thermal stability of the oxyhydride in question and the ionic mobility of the reactants.

• Fjellvåg, Øystein Slagtern; Armstrong, Jeff; Vajeeston, Ponniah & Sjåstad, Anja Olafsen (2018). New Insights into Hydride Bonding, Dynamics, and Migration in La2LiHO3 Oxyhydride. The Journal of Physical Chemistry Letters. ISSN 1948-7185. s. 353–358. doi: 10.1021/acs.jpclett.7b03098. Fulltekst i vitenarkiv Vis sammendrag

  Hydride anion-conducting oxyhydrides have recently emerged as a brand new class of ionic conductors. Here we shed a first light onto their local vibrations, bonding mechanisms, and anion migration properties using the powerful combination of high-resolution inelastic neutron scattering and a set of rigorously experimentally validated density functional theory calculations. By means of charge-density analysis we establish the bonding to be strongly anisotropic; ionic in the perovskite layer and covalent in the rock salt layer. Climbing nudged elastic band calculations allow us to predict the hydride migration paths, which crucially we are able to link to the observed exotic ionic–covalent hybrid bonding nature. In particular, hydride migration in the rock salt layer is seen to be greatly hindered by the presence of covalent bonding, forcing in-plane hydride migration in the perovskite layer to be the dominant transport mechanism. On the basis of this microscopic insight into the transport and bonding, we are able to propose future candidates for materials that are likely to show enhanced hydride conductivity.

• Getz, Michael; Hansen, Per-Anders Stensby; Fjellvåg, Øystein Slagtern; Ahmed, Mohammed Amin Karim; Fjellvåg, Helmer & Nilsen, Ola (2017). Intense NIR emission in YVO4:Yb3+ thin films by atomic layer deposition. Journal of Materials Chemistry C. ISSN 2050-7526. 5(33), s. 8572–8578. doi: 10.1039/c7tc02135f. Fulltekst i vitenarkiv
• Fjellvåg, Øystein Slagtern; Armstrong, Jeff; Slawinski, Wojciech Andrzej & Sjåstad, Anja Olafsen (2017). Thermal and Structural Aspects of the Hydride-Conducting Oxyhydride La2LiHO3 Obtained via a Halide Flux Method. Inorganic Chemistry. ISSN 0020-1669. 56(18), s. 11123–11128. doi: 10.1021/acs.inorgchem.7b01409. Fulltekst i vitenarkiv Vis sammendrag

  Oxyhydrides, in which oxide and hydride anions share the same anionic lattice, are relatively rare compounds. La2LiHO3 belongs to this family. We report the synthesis of La2LiHO3 by means of an alkali halide flux method, which allows the production of larger quantities of material relative to the usually adopted synthesis routes. Powder X-ray and neutron diffraction studies show that La2LiHO3 adopts an n = 1 Ruddlesden–Popper (RP)-type structure with an orthorhombic distortion (Immm) due to hydride and oxide anion ordering. No sign of polymorphism is observed. La2LiHO3 is seen to decompose in an oxygen atmosphere at ∼450 °C into La2LiO3.5. We show that the high mobility of hydride anions close to the decomposition temperature is likely the main factor in inducing the oxidation. The crystal structure of La2LiO3.5 is also determined and takes an n = 1 RP-type structure with an orthorhombic distortion (Fmmm). This newly reported large-scale synthesis approach, combined with the proven high thermal stability, is a key factor for potential practical applications of this oxyhydride in real devices.

• Napari, M; Tarvainen, O; Kinnunen, S; Arstila, K; Julin, J & Fjellvåg, Øystein Slagtern [Vis alle 9 forfattere av denne artikkelen] (2017). The α and γ plasma modes in plasma-enhanced atomic layer deposition with O2-N2 capacitive discharges. Journal of Physics D: Applied Physics. ISSN 0022-3727. 50(9). doi: 10.1088/1361-6463/aa59b3. Fulltekst i vitenarkiv
• Gan, Jiantuo; Gorantla, Sandeep Madhukar; Riise, Heine Nygard; Fjellvåg, Øystein Slagtern; Diplas, Spyridon & Løvvik, Ole Martin [Vis alle 9 forfattere av denne artikkelen] (2016). Structural properties of Cu2O epitaxial films grown on c-axis single crystal ZnO by magnetron sputtering. Applied Physics Letters. ISSN 0003-6951. 108:152110(15), s. 1–5. doi: 10.1063/1.4945985. Vis sammendrag

  Epitaxial Cu2O films grown by reactive and ceramic radio frequency magnetron sputtering on single crystalline ZnO (0001) substrates are investigated. The films are grown on both O- and Zn-polar surface of the ZnO substrates. The Cu2O films exhibit a columnar growth manner apart from a ∼5 nm thick CuO interfacial layer. In comparison to the reactively sputtered Cu2O, the ceramic-sputtered films are less strained and appear to contain nanovoids. Irrespective of polarity, the Cu2O grown by reactive sputtering is observed to have (111)Cu2O||(0001)ZnO epitaxial relationship, but in the case of ceramic sputtering the films are found to show additional (110)Cu2O reflections when grown on O-polar surface. The observed CuO interfacial layer can be detrimental for the performance of Cu2O/ZnO heterojunction solar cells reported in the literature.

• Slawinski, Wojciech Andrzej; Fjellvåg, Øystein Slagtern; Ruud, Amund & Fjellvåg, Helmer (2016). A novel polytype - The stacking fault based γ-MoO3 nanobelts. Acta Crystallographica. Section B: Structural Science, Crystal Engineering and Materials. ISSN 2052-5192. 72(2), s. 201–208. doi: 10.1107/S2052520615024804.

Se alle arbeider i Cristin

• Talib, F.; Fjellvåg, Øystein Slagtern & Kenzelmann, M. (2023). Diffuse magnetic scattering in rare earth halides.
• Fjellvåg, Øystein Slagtern; Hernandez, A.; Tam, D.; Roessli, B.; Shin, S. & Medarde, M. [Vis alle 9 forfattere av denne artikkelen] (2023). 2D Rare Earth Trihalides.
• Fjellvåg, Øystein Slagtern; Keller, Lukas; Graf, D.; Zeitelhack, K.; Defendi, I. & Howard, A. [Vis alle 12 forfattere av denne artikkelen] (2023). Cold Neutron Diffractometer DMC at SINQ.
• Sottmann, Jonas; Ruud, Amund; Fjellvåg, Øystein Slagtern; Vaughan, Gavin B. M.; Di Michel, Marco & Fjellvåg, Helmer [Vis alle 9 forfattere av denne artikkelen] (2023). Erratum: 5D total scattering computed tomography reveals the full reaction mechanism of a bismuth vanadate lithium ion battery anode (Phys. Chem. Chem. Phys. (2022) 24 (27075-27085) DOI: 10.1039/D2CP03892G). Physical Chemistry, Chemical Physics - PCCP. ISSN 1463-9076. doi: 10.1039/d3cp90076b.
• Fjellvåg, Øystein (2021). Neutron scattering to understand oxyhydrides, complex intermetallics, and fluoroperovskites.
• Fjellvåg, Øystein; Armstrong, J; Krzystyniak, Matthew; Vajeeston, Ponniah & Sjåstad, Anja Olafsen (2020). Structure and dynamics of La2LiHO3.
• Wragg, David; Fjellvåg, Øystein; Fjellvåg, Helmer; Sottmann, Jonas; Vaughan, Gavin B M & Di Michel, Marco [Vis alle 7 forfattere av denne artikkelen] (2020). Operando Total Scattering Computed Tomography: Making the Invisible Visible .
• Fjellvåg, Øystein; Sønsteby, Henrik Hovde; Nilsen, Ola; Wolff, Max; Kapaklis, Vassilios & Fjellvåg, Helmer [Vis alle 8 forfattere av denne artikkelen] (2020). Towards Multiferroic Thin Film Composites by Atomic Layer Deposition (ALD) .
• Wragg, David; Fjellvåg, Øystein; Ruud, Amund; Fjellvåg, Helmer; Vajeeston, Ponniah & Vaughan, Gavin B M [Vis alle 9 forfattere av denne artikkelen] (2019). XRD/PDF computed tomography and how to get the best possible operando data from ion batteries.
• Wragg, David; Ruud, Amund; Fjellvåg, Øystein; Fjellvåg, Helmer; lebedev, Oleg & Di Michel, Marco [Vis alle 9 forfattere av denne artikkelen] (2019). PDF Analysis of Batteries Using Diffraction Computed Tomography.
• Wragg, David; Ruud, Amund; Fjellvåg, Helmer; Fjellvåg, Øystein; Vajeeston, Ponniah & Sottmann, Jonas [Vis alle 9 forfattere av denne artikkelen] (2019). PDF Analysis of Batteries Using Diffraction Computed Tomography.
• Fjellvåg, Øystein; Kristin Hubred, Nygård; Ponniah, Vajeeston; Jeff, Armstrong; Matthew, Krzystyniak & Anja Sjåstad, Olafsen (2019). Synthesis, thermal stability and ionic mobility of the oxyhydride La2-xNdxLiHO3.
• Wragg, David; Sottmann, Jonas; Ruud, Amund; Fjellvåg, Øystein & Vaughan, Gavin B M (2018). Combined refinement of XRD and PDF data from nanomaterials.
• Wragg, David; Sottmann, Jonas; Ruud, Amund; Fjellvåg, Helmer; Fjellvåg, Øystein & Vajeeston, Ponniah [Vis alle 9 forfattere av denne artikkelen] (2018). Operando X-ray Diffraction Studies of Battery Materials.
• Wragg, David; Ruud, Amund; Sottmann, Jonas; Vajeeston, Ponniah; Fjellvåg, Helmer & Fjellvåg, Øystein [Vis alle 8 forfattere av denne artikkelen] (2018). New Anodes for Sodium and Lithium Ion Batteries.
• Fjellvåg, Øystein Slagtern & Sjåstad, Anja Olafsen (2017). Oxyhydrides, a new material class of complex mixed anion compounds.
• Fjellvåg, Øystein Slagtern; Sjåstad, Anja Olafsen & Armstrong, Jeff (2016). Hydride oxides with perovskite related structure: Case study of La2LiHO3.
• Fjellvåg, Øystein Slagtern; Fjellvåg, Helmer; Liu, Xin; Haugsrud, Reidar & Sjåstad, Anja Olafsen (2015). Hydride oxides with perovskite related structure: Case study of La2LiHO3.
• Fjellvåg, Øystein Slagtern; Sjåstad, Anja Olafsen; Haugsrud, Reidar & Gunnæs, Anette Eleonora (2015). Investigation of Novel Hydride Oxides for Holistic Understanding of Functional Materials.
• Fjellvåg, Øystein Slagtern; Ruud, Amund; Sønsteby, Henrik; Fjellvåg, Helmer & Nilsen, Ola (2014). Crystallization and electrochemical investigation of α- and β-MoO3 thin films deposited by Atomic Layer Deposition.
• Sønsteby, Henrik; Østreng, Erik; Fjellvåg, Øystein Slagtern; Nilsen, Ola & Fjellvåg, Helmer (2014). Sodium- and Potassium Containing Thin Films by Atomic Layer Deposition.
• Tollin, Hallvard Rise; Sjåstad, Anja Olafsen & Fjellvåg, Øystein (2021). Syntese og karakterisering av hydridoksider. Universitetet i Oslo. Vis sammendrag

  Denne masteroppgaven har fokus på syntese og karakterisering av hydridoksidene med sammensetningen Ln2LiHO3 (Ln = La, Nd), Sr substituert La2LiHO3, LaSr3Fe3HxOy og HoHO. Motivasjonen for valg av de nevnte hydridoksidsystemene er som følgende: Ln2LiHO3 (Ln = La, Nd) er velstudert og derfor en god kandidat for å få mekanistisk innsikt i hvordan hydridoksider nukleerer og gror i en saltfluks. Sr substituert La2LiHO3 har potensiale som et ioneledende materiale med mobilitet av hydridaniont, mens for HoHO er ikke trend for ordning av anioner forstått relativt til Ln-ioneradius (Ln < Nd gir uordnet aniongitter) og dette må verifiseres. LaSr3Fe3HxOy er interessant som hydridoksid da det aldri tidligere er rapportert hydridoksid inneholdende det 3d redoks-aktive jern-kationet, eller som inntar RP3-struktur. Systemene Ln2LiHO3 (Ln = La, Nd) og Sr substituert La2LiHO3, ble syntetisert med fluksmetoden. Det ble også utviklet metodikk for in –situ pulver-røntgendiffraksjon studier av nukleering og vekst av Nd2LiHO3. LaSr3Fe3HxOy ble syntetisert ved topotaktisk ionebytte og HoHO med kerammetoden. Strukturanalyse ble gjort med røntgendiffraksjon, og i tillegg ble det foretatt termisk stabilitetsanalyser med TGADSC. Forbindelsene LaSr3Fe3HxOy og HoHO ble studert med nøytrondiffraksjon. For første gang er Sr substituert La2LiHO3 fremstilt med fluksmetoden. Srsubstitusjonsgraden er lavere enn forventet (ca. 20 % av nominell sammensetning), men det foreligger gode bevis for at en Sr-rik tetragonal fase stabiliseres i fluks ved høy konsentrasjon av Sr (x + y > 0,5 i La2-x-ySrx+yLiH1+2yO3-(x/2)-y). For ortorombisk Sr substituert La2LiHO3 er substitusjonsmekanismen aliovalent anionsubstitusjon. HoHO tar en F-43m type struktur og er anion-ordnet med identisk bindingsavstand for Ho-O og Ho-H. Basert på TGA-DSC, strukturanalyse fra nøytrondata og BVS er hydridoksidet LaSr3Fe3H1,07O8,6 fremstilt. Det er allikevel usikkerhet knyttet til det faktum at forbindelsen er et hydridoksid, så dette må verifiseres.

• Fjellvåg, Øystein; Sjåstad, Anja Olafsen & Gunnæs, Anette Eleonora (2019). Oxyhydrides - Synthesis, Crystal Structure and Properties. Universitetet i Oslo. ISSN 1501-7710. 2019(2153).

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