High-Pressure and -Temperature Synthesis and its XPS Study of La_1-xNa_xTiO₃

Abstract

Perovskite oxides of La_1-xNa_xTiO₃ (x=0. 05, 0. 1-0. 5) were synthesized under high-pressure and -temperature. XRD analysis showed that sample is cubic for x=0. 05 and pseudo-cubic for 0. 1≤x≤0. 5. Cell volumes of samples with 0. 1≤x≤0. 5 decrease as x increase, and the cell volume for x=0. 05 is less than that for x=0. 1. This implies that the deficiency of cation may exist in the samples. XPS and EPR measurements indicated that Ti ions were mixed valence of +3 and +4 and vacancy of A-site ions existed in samples. The valence state of Ti ions can be altered by high-pressure and -temperature.