Spray-dried sol-gel glass-ceramic powders based on the tunable thermal expansion of quartz and keatite solid solutions

Lithium aluminosilicate glass-ceramic powders were synthesized by the heat treatment of spray-dried sol-gel glassy nanobeads, obtaining quartz solid solution (Qss) and keatite solid solution (Kss) crystals. Their composition ranged between 75 mol% SiO2 and pure silica along the spodumene join. The metastable crystals displayed tunable coefficients of thermal expansion ranging from +30 × 10−6 to −2.7 × 10−6 K−1 at room temperature, as obtained from their crystallographic characterization. The solid solution boundaries of Kss could be extended to 85 mol% SiO2. Concurrently, X-ray diffraction measurements performed in situ at high temperature and at cryogenic conditions confirmed the known linear shift of the high-low quartz inversion temperature upon increasing Al+Li doping. The obtained results qualify aerosol synthesis as a very versatile method for the production of glass-ceramic powders in the LAS system.