Light-induced properties of doped Bi4Ge3O12 single crystals

Abstract

Optically homogeneous bismuth germanate Bi4Ge3O12 single crystals doped with vanadium, cobalt and vanadium plus cobalt have been successfully grown by Czohralski technique with automatically diameter-weight control. The distribution coefficients for individual doping elements are determined. The effect of doping on the light-induced properties of BGO single crystals is studied. Optical absorption spectrum of annealed samples can be strongly modified under ultraviolet illumination. The photochromic effect is optically or thermally reversible from one state to another. Volt-amper charactersitcs show linear behavour and dark conductivity values are sigma similar to 10(-13) (Omega.cm)(-1). Holographic grating were successfully recorded in all investigated doped crystals at 514 nm.