Effects of bond character on the electronic structure of brownmillerite-phase oxides , Ca 2 B ′ x Fe 2−x O 5 ( B ′ = Al, Ga): an X-ray absorption and electron energy loss spectroscopic study

Brownmillerite-phase transition-metal oxides, Ca2B′xFe2−xO5 (B′ = Al, Ga), have been examined by use of X-ray absorption near-edge spectroscopy (XANES) and electron energy loss spectroscopy (EELS). These studies were performed to examine how the electronic structure was affected as a more (Ga) or less (Al) electronegative metal was substituted for Fe. The oxygen deficient perovskite-like structure is built up of alternating layers having either …