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

Abstract

AbstractLithium 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.