Dopedγ-Bi2O3: synthesis of microcrystalline samples and crystal chemical analysis of structural data

Abstract

A series of microcrystalline products containing theγ-Bi2O3phase doped with Co, Fe, Mn, Pb, Sb, Si, Ti, V and Zn has been prepared by solid state reaction. Based on the heating temperature and heating time, the following order of increasing relative stability of the dopedγ-Bi2O3phases was established: Sb5+< Co2+≈ Mn4+< Fe3+≈ Si4+< Ti4+< V5+< Zn2+< Pb2+. The unit cell parameters of the prepared samples were compared with available structural data, which were also further analyzed concerning the geometrical parameters and overall reliability. The analysis confirmed the so-called Radaev’s model for the dopedγ-Bi2O3structure, which assumes the presence of Bi23+ions slightly displaced from the tetrahedral M site and corresponding vacancies (resulting from a lone pair on Bi23+) in the coordinating oxygen positions. In addition, the analysis suggested that this model can be further improved. The existence of an approximate linear relationship between the unit cell parameters of the dopedγ-Bi2O3phases and the ionic radii of the M cations was found.