Influence of water on nucleation kinetics in silicate melt

Steady-state rates and induction times for crystal nucleation in lithium disilicate melt depend exponentially on water content (up to 975 ppm). Time-dependent crystal number densities exhibit self-similar behavior as a function of water content, thereby allowing for a description of all data by a universal curve. This behavior provides a powerful tool for predicting crystallization histories, implies that mechanisms involved in nucleation are accelerated by water, and suggests that no new reaction pathways arise with the addition of water. The influence of water on crystal nucleation cannot be solely explained by the effect of water on viscosity; in addition, the free energy barrier to nucleation is reduced similar to 8% with an addition of water from 130 to 975 ppm. (C) 1997 Elsevier Science B.V.