Glass Transition Temperatures Studied by MD Simulation of Some Alkali Metasilicates

Abstract

Molecular dynamics simulation of some alkali metasilicates (M₂SiO₃, M = Li, Na, K) was performed to compare glass transition temperatures, T_g , defined in various ways. The potential parameters derived from ab initio MO calculations were used and found to reproduce the inflection of V-T relation on cooling the system. The T_g defined by the inflection point corresponds well to that defined by geometrical changes of coordination polyhedra found in previous work. The self-diffusion coefficients of the alkali ions in higher temperature regions were shown to be related to the amount of free volume in these systems.