Decrystallization of glass-ceramics under ion exchange diffusion

Experimental results of studying ion exchange process in glass-ceramics are presented. For the first time, it is discovered that the process may resul t in the disappearance of the crystalline phase in the layers undergoing io n exchange diffusion. This new phenomenon has been called the effect of dec rystallization. The effect has been observed in a ceramic material formed o ut of a photosensitive Ag-doped lithium-silica glass, which can be crystall ized owing to the photo-induced formation of fine silver particles as the n uclei for the growth of Li2O . SiO2 crystals. Samples of the glass-ceramics were subjected to ion exchange in NaNO3 salt melt at the temperature at wh ich viscosity of the initial glass is equal to 10(8) Ns/m(2). On processing , pure vitreous layers under all the faces of the sample processed have bee n obtained the depth of those layers depending on the processing time. (C) 1999 Elsevier Science Limited. All rights reserved.