Structure and magnetism in rare earth strontium-doped cobaltates

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Substantial interest has recently been generated by rare earth cobaltate compounds as cathode materials for solid oxide fuel cells. We have synthesised a wide range of single–phase perovskite-based rare earth cobaltates (Ln1−xSrxCoO3−δ) (Ln=La3+–Yb3+). A combination of electron and X-ray diffraction of these phases reveals a complex family of tetragonal and orthorhombic superstructures. The nature of structural and magnetic ordering relies on both cation and oxygen vacancy distribution. Phase boundaries exists between compounds containing large, medium and small rare earths (between Nd3+ and Sm3+, and also between Gd3+ and Dy3+) and also at different Sr-doping levels. Powder neutron diffraction has been used in conjunction with the other techniques to reveal cation and oxygen vacancy ordering within these materials. These phases show mixed valence (3+/4+) cobalt oxidation states that increases with Sr content. A range of magnetic behaviours has been observed, including ordered antiferromagnetism at elevated temperatures (>300 K) in Ho0.2Sr0.8CoO2.75. © 2006 Elsevier B.V.
Physical copy held by ANSTO Library at DDC 539.7213/3. Part I
Neutron diffraction, Phase diagrams, Cubic lattices, Strontium, Doped materials, Vacancies, Oxygen, Magnetism, Rare earth compounds, Solid oxide fuel cells, X-ray diffraction, Valence, Antiferromagnetism
James, M., Morales, L., Wallwork, K., Avdeev, M., Withers, R., & Goossens, D. (2006). Structure and magnetism in rare earth strontium-doped cobaltates. Paper presented at the Eighth International Conference on Neutron Scattering (ICNS 2005), "Neutrons for structure and dynamics - a new era", Sydney, Australia, 27 November to 2 December 2005. In Campbell, S. J., Cadogan, J. M., Furusaka, M., Hauser, N., & James, M. (Eds), Physica B: Condensed Matter, 385–386(Part 1), 199-201. doi:10.1016/j.physb.2006.05.244