The influence of thermal treatment in oxi-reductive environments on the surface of Bi4Ge3O12, B12GeO20 and Bi12SiO20 single crystals

Thermal treatments at temperatures ranging from 400 to 800 °C were performed on single crystal samples of Bi4Ge3O12, Bi12GeO20 and Bi12SiO20, in N2-H2 and O2-water vapor atmospheres. The H+ content of the samples remained unchanged after the treatments. These treatments lead to surface reduction which is analyzed by electron microprobe.