Analysis of phase transition by variation of oxide ion content in BaFe_(0.9)In_(0.1)O_(3-δ) as oxygen storage material using Mossbauer spectroscopy - Discovery of magnetic phase transition with cubic structure maintained

摘要

Perovskite-type BaFe0.9In0.1O3-delta (BFI010) with random distribution of oxide ion vacancy was prepared by Pechini method with sintering under O-2 flow (BFI010-O-2) and N-2 flow (BFI010-N-2). Although crystal structures of the obtained specimens could be explained as the same cubic perovskite, the large variation in oxide ion vacancy content delta was observed between these specimens. Relationship between chemical state of Fe ions and delta was evaluated using Mossbauer spectroscopy at room temperature. It was revealed that valence of Fe was mixture of Fe3+ with isomer shift, I.S., of 0.260 mm/s and Fe4+ with I.S. of -0.073 mm/s with paramagnetic property in BFI010-O-2. Mossbauer spectrum of BFI010-N-2 could be explained that only Fe3+ with antiferromagnetic interaction existed, indicating different phases could be obtained by variation of delta in BaFe0.9In0.1O3-delta in spite of the same cubic crystal structure. It was concluded that oxygen storage phenomenon due to redox variation of Fe ions occurred between the two different phases without variation of crystal structure. (C) 2018 Elsevier B.V. All rights reserved.