FIRST MEASUREMENTS OF TIME-DEPENDENT NUCLEATION AS A FUNCTION OF COMPOSITION IN NA2O-CENTER-DOT-2CAO-CENTER-DOT-3SIO(2) GLASSES

First measurements of the composition dependence of the time-dependent nucleation rate are presented. Nucleation rates of the stoichiometric crystalline phase, Na2O . 2CaO . 3SiO(2), from quenched glasses made with different SiO2 concentrations were determined as a function of te mperature and glass composition. A strong compositional dependence of the nucleation rates and a weak dependence for the induction times wer e observed. Using measured values of the liquidus temperatures and gro wth velocities as a function of glass composition, these data are show n to be consistent with predictions from the classical theory of nucle ation, assuming a composition-dependent interfacial energy. (C) 1997 E lsevier Science B.V.