An Analysis of Nucleation‐Rate Type of Curves in Glass as Determined by Differential Thermal Analysis

The nucleation rate ( I ) versus temperature type of curves for a Na 2 O2·CaO·3SiO 2 (NC 2 S 3 ) glass doped with 0.1 wt% platinum, 0.5 wt% Ag 2 O, and 2.0 wt% P 2 O 5 were determined using a previously developed differential thermal analysis (DTA) technique. In this DTA technique, a constant amount of glass sample was nucleated at selected temperatures for a specific time, followed by a DTA scan at a fixed heating rate. The functional dependence of the maximum intensity of the exothermic DTA crystallization peak ((delta T ) p ) or the inverse temperature at the DTA peak maximum ( T p −1 ) on the nucleation temperature ( T n ) was used to determine the nucleation rate versus temperature type of curves. Calculations for qualitatively assessing the dependence of (delta T ) p on T n were performed using I and crystal growth rate ( U ) curves for a hypothetical system. Values of (delta T ) p calculated for different degrees of overlap between the I and U curves were compared with those measured experimentally. The (delta T ) p vs T n curves depended strongly on the overlap of I and U , whereas the T p −1 vs T n curves were unaffected by the overlap.