Gel-derived amorphous cesium-aluminosilicate powders useful for formation of pollucite glass-ceramics

Amorphous powders in the Cs₂O–Al₂O₃−SiO₂ system were prepared by sol-gel processing. Gels made from TEOS, Al-chelate, and Cs-acetate were dried and calcined to obtain molecularly mixed powders of analyzed compositions in the range useful for conversion to pollucite (CsAlSi₂O₆) glass-ceramics. X-ray diffraction (XRD), differential thermal analysis (DTA), thermogravimetry (TG), and scanning electron microscopy (SEM) were used to characterize the powders. A typical amorphous powder of analyzed chemical composition (in wt.%) = 28.05Cs₂O, 37.77SiO₂, and 37.96Al₂O₃ was found to have a glass transition temperature of 945 °C and a glass crystallization temperature of 1026 °C. Preliminary experimental results of densification and crystallization of the amorphous powders show pollucite/mullite phases to be present.