INFLUENCE OF THE STRUCTURAL RELAXATION OF A GLASS ON THE REFRACTIVE-INDEX GRADIENT IN ION-EXCHANGE AT TEMPERATURES NEAR T-G

A kinetic model of the formation of a gradient-index glass layer in the temperature range of transition from low-temperature to high-temperature ion exchange in a glass-salt melt system is proposed. The known temperature and time dependences of the formation of gradient-index layers upon lithium-sodium ion exchange are described with due regard for the mutual influence of ion exchange at the glass-salt melt interface, interdiffusion of cations, and structural relaxation of a glass under the action of diffusant ions.