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

Recent publications demonstrate that the maximum homogeneous nucleation rates, I-max of silicate glasses strongly diminish with the reduced glass transition temperature, T-gr (= T-g/T-m/L), where T-g is the glass transition temperature and T-m/L is the melting point or liquidus temperature). In addition, the critical cooling rates for metallic glass formation, R,, also drop with rising T-gr. From these empirical observations as well as from theoretical considerations, it is expected that the maximum crystal growth rates, U-max, also depend on T-gr. In this paper we test and confirm this assumption by plotting experimental U-max vs. T-gr 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 U-max(T-gr) and in the temperature of the maximum crystal growth rate, T-max(U). These in findings indicate that the screw, dislocation growth,th model is a good approximation to describe crystal growth in silicate glasses. (c) 2005 Elsevier B.V. All rights reserved.