Densifieation and Crystallisation of Celsian Glass Derived from Alkoxide Gel

High density (98% of theoretical) was achieved at 900 degrees C for an all-alkoxide derived bulk celsian gel prior to crystallisation. TEM indicated that crystallisation was dominated by volume nucleation and growth of hexagonal disc shaped hexacelsian. Kinetic studies using SEM indicate a maximum nucleation rate at 980 degrees C and an activation energy for crystal growth of 566 KJ/mol. The high rates of densification and of nucleation are attributed to the high OH content in the gel-derived glass.