Influence of ion-exchange treatment on the physicochemical properties of glass and waveguide surfaces

The paper sums up and discusses the results of published and still unpublished research works performed by the author and his colleagues. The results of complex investigations into the influence of ion-exchange treatment on the physicochemical surface properties of oxide glasses and planar waveguides on their base are generalized. It is demonstrated that the low-temperature treatment of silicate and phosphate glasses in alkali metal nitrate and silver nitrate melts leads to changes in the optical quality of glass surface, macrorelief of surface, shape of a sample, optical strength, microhardness, heat resistance, and photosensitivity. In addition, such a treatment brings about changes in acoustic, luminescence, photochemical, and photoemission properties of the glass surface and also in the valence and coordination states of impurity ions. It is shown that many physicochemical characteristics of glasses can be "improved" or can "deteriorate" upon ion exchange as compared to those of the initial glasses, depending on the treatment temperature and duration, as well as on the type of exchanging ions. The surface-glass layers can "acquire" radically new properties (photosensitivity gradient, displacement of photosensitivity boundary, piezodichroism of color centers, and orientation of microcrystals in the field of diffusion stresses). Consideration is given to the practical application of the effects observed upon ion exchange.