Rapid thermal bleaching in doped sillenites

Thermal stability of photochromic effect existing at temperatures below 100 K in scandium doped germanium sillenites (BGO:Sc) was investigated. The single crystals of sillenites were obtained by the Czochralski technique. Some thermally stimulated processes related to the photochromic properties of doped sillenites were noticed. Process of thermal bleaching was studied in a wide spectral range and in various conditions. Both equilibrium thermal bleaching and non-equilibrium one leading to so called thermoabsorption were intensively studied. On the base of proposed model of thermoabsorption the energies of trap centers were calculated. It has been shown that some optical properties of sillenites are very sensitive to the procedure and conditions in which the coloring process was provided.