First measurements of time-dependent nucleation as a function of composition in Na₂O · 2CaO · 3SiO₂ glasses

First measurements of the composition dependence of the time-dependent nucleation rate are presented. Nucleation rates of the stoichiometric crystalline phase, Na₂O · 2CaO · 3SiO₂, from quenched glasses made with different SiO₂ concentrations were determined as a function of temperature and glass composition. A strong compositional dependence of the nucleation rates and a weak dependence for the induction times were observed. Using measured values of the liquidus temperatures and growth velocities as a function of glass composition, these data are shown to be consistent with predictions from the classical theory of nucleation, assuming a composition-dependent interfacial energy.