Correlation between maximum crystal growth rate and glass transition temperature of silicate glasses

Abstract

Recent publications demonstrate that the maximum homogeneous nucleation rates, I-max of silicate glasses strongly diminish with the reduced glass transition temperature, Tgr (= Tg/Tm/L), where Tg is the glass transition temperature and Tm/L is the melting point or liquidus temperature). In addition, the critical cooling rates for metallic glass formation, Rcr, also drop with rising Tgr. From these empirical observations as well as from theoretical considerations, it is expected that the maximum crystal growth rates, Umax, also depend on Tgr. In this paper we test and confirm this assumption by plotting experimental U-max vs. Tgr for 20 silicate glasses, and then use the most common crystal growth model - screw dislocation growth - to calculate and compare maximum experimental growth rates with theoretical predictions. Despite several assumptions made for the calculations, there is good agreement between theory and experiment, both in the magnitude of Umax(Tgr) and in the temperature of the maximum crystal growth rate, Tmax(U). These in findings indicate that the screw, dislocation growth,th model is a good approximation to describe crystal growth in silicate glasses.