Preparation and structure characteristics of nano-Bi₂O₃ powders with mixed crystal structure

Abstract

The nano-Bi₂O₃ powders were prepared by a chemical precipitation method with Bi(NO₃)₃, HNO₃ and NaOH as reactants. The structural characteristics and morphology of nano-Bi₂O₃ powders were investigated by X-ray diffraction and transmission electron microscopy, respectively. The results show that under the optimum condition that 300 g/L Bi(NO₃)₃ reacts at 90°C for 2 h, the Bi₂O₃ powders with 60 nm on the average and 99.5% in purity are obtained. The prepared nano-Bi₂O₃ powders contain a mixed crystal structure of monoclinic and triclinic instead of traditional structure of monoclinic α-Bi₂O₃. And the mixed crystal structure is stable in air. The reason for the appearance of the mixed crystal structure may be that the ionic radius ratio of Bi³⁺ to O²⁻ changes easily during the formation of nano-Bi₂O₃ particles by a chemical precipitation method.

Keywords

nano-Bi₂O₃ powders / chemical precipitation method / mixed crystal structure