1. A Novel Complex Cobalt Gallium Oxide Ca2Co0.8Ga1.2O4.8: Synthesis and High-Temperature Electron Transport Properties
- Author
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Istomin, S. Ya., Antipov, E. V., Svensson, G., Attfield, J. P., Kozhevnikov, V. L., Leonidov, I. A., Patrakeev, M. V., and Mitberg, E. B.
- Subjects
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OXIDES , *GALLIUM compounds , *COBALT compounds , *X-ray diffraction - Abstract
A new complex oxide with the cation ratio Ca:Co: Ga=2:0.8:1.2 has been synthesized in air at 1150oC. The cobalt atoms adopt oxidation states 2+ and 3+ in equal amounts giving an oxygen content corresponding to the composition Ca2Co0.8Ga1.2O4.8. It crystallizes in F-centered cubic structure with a=15.0558 A˚. Conductivity measurements performed at high temperatures revealed that the temperature increase gives a charge disproportionation of Co3+ species resulting in a small concentration of Co4+ species and thus a small p-type conductivity in the oxide. A decrease of the oxygen pressure promotes oxygen depletion from the oxide and a deterioration of the conductivity. The electric properties are interpreted within a small polaron conduction mechanism. An unusually large mobility activation energy of 0.45 eV can be explained by a large spatial separation of cobalt cations in the structure. [Copyright &y& Elsevier]
- Published
- 2002
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