Influence of some dopants on optical properties of Bi12GeO20 and Bi12SiO20 single crystals grown by the Czochralski technique

BGO and BSO single crystals, pure and doped, have been grown by the Czochralski technique. The influence of natural and forced convection flows in the melt on the distribution of dopants in as grown single crystals has been discussed. Strong photochromic effect for such dopants as Cr, Mn and Cu has been observed. The change of the coloration from pale yellow to colorless has been found in case of sulphur doping.