A Novel Complex Cobalt Gallium Oxide Ca2Co0.8Ga1.2O4.8: Synthesis and High-Temperature Electron Transport Properties
✍ Scribed by S.Ya. Istomin; E.V. Antipov; G. Svensson; J.P. Attfield; V.L. Kozhevnikov; I.A. Leonidov; M.V. Patrakeev; E.B. Mitberg
- Publisher
- Elsevier Science
- Year
- 2002
- Tongue
- English
- Weight
- 294 KB
- Volume
- 167
- Category
- Article
- ISSN
- 0022-4596
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✦ Synopsis
A new complex oxide with the cation ratio Ca:Co: Ga=2:0.8:1.2 has been synthesized in air at 1150 o C. The cobalt atoms adopt oxidation states 2+ and 3+ in equal amounts giving an oxygen content corresponding to the composition Ca 2 Co 0.8 Ga 1.2 O 4.8 . It crystallizes in F-centered cubic structure with a ¼ 15:0558 ( A. Conductivity measurements performed at high temperatures revealed that the temperature increase gives a charge disproportionation of Co 3+ species resulting in a small concentration of Co 4+ 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. # 2002 Elsevier Science (USA)