Synthesis of Monoclinic Celsian from Seeded Alkoxide Gels

Celsian gels seeded with fine monoctinic celsian seeds were prepared by an all-alkoxide gel route and the effect of seeding on crystallization of the gel-derived glass examined. Gels seeded with 10 wt.% of fine crystals sintered to greater than 93% and 95% density in the form of cold pressed gel powder pellets and as bulk gel respectively, when sintered at temperatures below 1050 degrees C. XRD analysis indicated that seed facilitated the formation of monoclinic celsian in the densified celsian glass, and the amount of monoclinic celsian formed increased with increasing seed content. 92% of the glass crystallized into monoclinic celsian when 10% of 3.2 mu m seeds were introduced. Transmission Electron Microscopy revealed epitaxial growth of monoclinic celsian from the crystal seeds but homogeneous nucleation and growth of hexacelsian.