Ceramics-Silikáty 34, (1) 49 - 60 (1990)

Finely dispersed powders of lithium, calcium and strontium titanates were prepared by precipitation in molten salts. The influence of temperature and of the time of heat treatment on the mean crystal size was determined. The mean crystal size was found to increase with temperature and time,however, at a constant temperature the rate of crystal growth slowed down with time. This indicated that the isothermal crystal growth is not an isolated process and is apparently accompanied bt formation of new crystallization nuclei. It is assumed that the crystallization process is governed by two different mechanisms: in the initial stage, the crystal growth is controlled by surface reaction while in the subsequent stage, with the formation of a concentration gradient at the phase boundary, diffusion becomes the predominant factor and the rate of the crystallization is gradually slows down.