Electronic structures of Fe in La_1−x Ba _x FeO_3−y (0≤x≤0.70)

Abstract

Mössbauer spectra of La_1−x Ba _x FeO_3−y recorded at room temperature for various values of x show a six-line and/or a single-line subspectrum. The six-line subspectrum with IS=0.41 mm/s and H=52 T results from an orthorhombic perovskite containing only Fe³⁺ ions. The single-line subspectrum at 0.17 mm/s from a cubic perovskite can be assigned to neither Fe³⁺ nor Fe⁴⁺ but to an intermediate valence state, which may be due to electron hopping between the Fe³⁺ and Fe⁴⁺ ions on the identical octahedral sites. The temperature dependence of electron hopping in the compound La_0.40Ba_0.60FeO_3−y is presented.