Solid State Ionics 17 (1985) 159-167 North-Holland, Amsterdam DEFECT STRUCTURES AND MIGRATION MECHANISMS IN OXIDE PYROCHLORES
نویسندگان
چکیده
Using computer simulation techniques the defect structure and oxygen ion migration mechanism of oxide pyrochlores (eg. Gd2Zr207) was investigated in order to explain the decreased activation enthalpy for oxygen ion conductivity as a function of order. Shell model potentials were found to be necessary in order to obtain sufficiently accurate physical properties for the pyrochlore compound. The oxygen Frenkel defect consisting of 'a split 48f vacancy' and 8b interstitial appeared to be the most stable instrlnslc defect, but vacancies related to extended defect structures may play an important role in the diffusion mechanism too. The migration mechanism of oxygen ions is mainly based on 48f-48f Jumps and involve 0.9 eV harrier energy, comparable with the experimental activation enthalples of 70-85 kJ/mol.
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