TEM study of a fluorite-type (1 − x)Bi2O3·xFe2O3 superstructure in BiFeO3 ceramics synthesized by the rapid liquid-phase sintering method

A commensurate modulated structure of (1 − x)Bi2O3·xFe2O3 is found in the BiFeO3 ceramics synthesized by the rapid liquid-phase sintering method. Transmission electron microscopy studies show that the superstructure is based on fluorite-type δ-Bi2O3 and modulated probably by oxygen vacancy ordering. The existence of such a superstructure may increase the leakage current of BiFeO3 ceramics.