X-RAY PHOTOELECTRON SPECTROSCOPIC STUDIES OF SELLINITE AND EULYTITE BGO AND BSO CRYSTALS

Single crystals of Bi12GeO20, Bi12SiO20, Bi4Ge3O12; and Bi4Si3O12 are grown by Floating zone and Czochralski techniques. The X-ray photoelec tron spectroscopic (XPS) studies have been carried out on BSO and EGO crystals. XPS is employed to characterise the surface quality and bulk nature of the crystals. The surface contamination on both types of cr ystals are identified. In addition to tile contamination. some amount of Bi atoms are observed with Bi ions on sellinite. It is demonstrated that the eulytite crystals are chemically more robust to degradation than the sellinite crystals. The predominant covalent and ionic charac ter of Bi4Ge3O12 and Bi4Si3O12 respectively is explained from their ox ygen 1s core level spectra.