Demystification of Mizusaki’s α-factor for the positively-deviated defect behavior of hyperstoichiometric oxides

Conference Dates

March 10-14, 2019


Many hyperstoichiometric (p-type) ternary or higher oxides of present technological interests, e.g., La1-xSrxCrO3-δ exhibit a positive deviation from the ideal defect structure. Mizusaki et al. [1] could beautifully explain the positively-deviated defect structure by introducing an empirical factor α such as


Here, ΔHxs stands for the excess enthalpy of oxidation reaction involving oxygen vacancies and holes or

1/2 O2+VO••=OOx+2h .

The authors[1] interpreted this α-factor as representing the interactions among lattice ions and defects, but its true physico-chemical face has since remained a mystery notwithstanding so frequent invoking to the defect chemistry stage.

It has recently turned out that this factor corresponds to the first order approximation of the hole-degeneracy effect. We will demystify this α-factor in this line.

[1] J. Mizusaki, S, Yamauchi, K. Fueki, and A. Ishikawa, “Nonstoichiometry of the perovskite-type oxide La1-xSrxCrO3-δ,” Solid State Ionics 12 (1984) 119.

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