Controlled Spherulitic Crystallization in 3BaO‐5SiO ₂ Glass

Abstract

Morphological stages in the internal crystallization of a 3BaO‐ 5SiO 2 glass were investigated. Spherulitic crystallization occurred between 800° and 950°C. After long times at the crystallization temperatures, the spherulites changed, apparently by secondary crystallization. Above 950°C, lath‐like crystals are formed by recrystallization of the spherulites. The effects of nucleation‐and‐growth heat treatments on the rate and morphology of crystallization were studied. The peak nucleation temperature was between 700° and 725°C, and all the crystalline forms were 3BaO.5SiO 2 .