Structural and raman vibrational studies of CeO2-Bi 2O3 oxide system

Abstract

A series of ceramics samples belonging to the CeO2- Bi 2O3 phase system have been prepared via a coprecipitation route. The crystallized phases were obtained by heating the solid precursors at 600 °C for 6 hours, then quenching the samples. X-ray diffraction analyses show that for x<0.20 a solid solution Ce1-x BixO 2-x/2 with fluorine structure is formed. For x ranging between 0.25 and 0.7, a tetragonal β' phase coexisting with the FCC solid solution is observed. For x ranging between 0.8 and 0.9, a new tetragonal β phase appears. The β' phase is postulated to be a superstructure of the β phase. Finally, close to x=1, the classical monoclinic Bi2O 3 structure is observed. Raman spectroscopy confirms the existence of the phase changes as x varies between 0 and 1. © 2009 L. Bourja et al.