The mechanical and optical properties of Li2Si2O5 glass-ceramics can be precisely controlled via the crystal morphology and content. However, the materials' coefficient of thermal expansion (CTE) depends on the fraction as well as the CTE of Li2Si2O5 and the residue glass phase, and therefore covers a rather narrow range between 10.2 and 11.3 *10-6 K-1 (100-400 deg C). This study presents a way to tailor the CTE of lithium disilicate-based glass-ceramics by controlled two-fold precipitation of Li2Si2O5 and CsAlSi5O12 as a minor crystal phase with high CTE from homogeneous Cs2O comprising bulk base glasses. The Cs2O content in the base glass significantly influences the nucleation and crystallisation process of Li2Si2O5 as well as the microstructure of the glass-ceramic materials.
