LIU Wei ¹, YANG Xingming ^{1, 2}, RUAN Yinjie ¹, YIN Handi ¹, XIA Jinfeng ¹, CHENG Guofeng ¹
(1. Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050, China; 2. School of Physics,
Nanjing University, Nanjing 210093, Jiangsu, China)

Abstract: The BiFeO₃ powders are prepared by the conventional solid state reaction, which have some impurity phases (Bi₂₅FeO_40, Bi₂Fe₄O₉).The effects of nitrating on the decomposition of the impurity phases in BiFeO₃ powders are studied by X-ray diffraction (XRD), backscatteredelectron (BSE) images and energy-dispersive spectrometry (EDS) quantitative analysis. The impurity phases of Bi₂Fe₄O₉ and BiFeO₃ cannot be nitrated by dilute nitric acid. However, Bi₂₅FeO₄₀ phase is metastable, which may be decomposed into nitrate of Bi³⁺ and Fe^3+. The effect of dilute nitric acid concentration on the decomposition rate of Bi₂₅FeO₄₀phase has also been discussed, which may provide a useful experimental guidance for the preparation of pure-phase BiFeO₃.

Key words: BiFeO₃; nitrating; decomposition; decomposition rate