Sintering properties of sol–gel derived lithium disilicate glass ceramics

Lithium disilicate (Li2Si2O5) glass-ceramics were fabricated through two sol–gel methods: the nitrate route and the alkoxide route. Thermal analysis revealed different crystallization processing of two gel-derived powders. Li2Si2O5 powders were obtained after heat treatment at 800 °C. These powders were pressed and pressureless sintered under 900–1030 °C. Microstructure of sintered samples revealed the grain size and morphology of Li2Si2O5 ceramics. Although grain size in both samples increased with increasing sintering temperature, samples from the alkoxide route derived powders had more uniform grain size and pore distribution. In addition, open porosity decreased in both samples with increasing sintering temperature. Unlike familiar nucleation that resulted in grain growth mechanism, the Li2Si2O5 particles developed into irregular large size grains at first, and then grew into rod-shaped grains