Diffusion of oxide ions in LaFeO3 single crystal |
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Authors: | Takamasa Ishigaki Shigeru Yamauchi Junichiro Mizusaki Kazuo Fueki Hiroyuki Naito Tatsuya Adachi |
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Institution: | Department of Industrial Chemistry, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113, Japan;Seiko Instruments & Electronics Ltd., Kameido, Koto-ku, Tokyo 136, Japan |
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Abstract: | The tracer diffusion coefficient, , of oxide ions in LaFeO3 single crystal was determined over the temperature range of 900–1100°C by the gas-solid isotopic exchange technique using 18O as a tracer. For the determination of , the depth profile of 18O was measured by means of a secondary ion mass spectrometer (SIMS). The surface exchange reaction was found to be slow and the surface exchange rate constant, k, was determined together with . It was found that at 950°C is proportional to P?0.58O2, where PO2 is an oxygen pressure. The vacancy mechanism was determined for the diffusion of oxide ions from the PO2 dependence. The vacancy diffusion coefficient, DV, for LaFeO3 was nearly the same as that for LaCoO3 at the same temperature. The activation energy for migration of oxide ion vacancies was 74 kJ · mole?1 for both oxides. |
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