OPTICAL-CENTERS OF CERIUM IN SILICA GLASSES OBTAINED BY THE SOL-GEL PROCESS

A spectral-luminescent study of Ce-containing silica gel-glasses doped at the sol stage and by impregnating porous xerogels with activator c hloride salt solutions has been performed. The influence of the degree of doping and redox conditions of vitrification on the activator char ge state and the content of hydroxyl ions and chlorine in the glass is considered. The preservation of the glass phase composition and the n on-linear increase in the visible absorption intensity with increasing activator concentration from 5 X 10(17) to 3.0 X 10(20) ions/cm(3) ar e noted. It is concluded that there are two main types of optical cent re. It is assumed that they represent Ce(III) oxygen complexes whose n earest surrounding includes quadruply charged (the first type) and tri ply charged (the second type) ions of cerium. Evidence has been obtain ed in favor of the superexchange excitation transfer to the cental ion of Ce(III) oxygen complexes from photoreduced to the triply charged s tate of the same ion name of Ce(IV) oxygen complexes.