Zn-substituted brownmillerite-type strontium ferrites

Resumo

New La/Zn substituted strontium ferrites Sr_{(2 −x)}La_x[Fe_{(2 − x)}Zn_x]O₅, (0 ≤ x ≤ 0.3) with brownmillerite- type structure are obtained and studied via X-ray phase analysis and Mössbauer spectroscopy. Depending on the conditions of synthesis, substituting Zn²⁺ cations can either mainly occupy tetrahedral positions in a brownmillerite structure, or be uniformly distributed between the tetrahedral and octahedral positions. It is shown that they are reversibly oxidized by atmospheric oxygen at elevated temperatures.