Microstructure and properties of spodumene based Li-Si-Al-O-N glass ceramics

Glasses and glass ceramics in the Li-Si-Al-O-N system were prepared using a natural mineral resource, and the microstructures and mechanical and thermal properties examined. The dominant phases that formed in the Li oxynitride glass ceramics were beta-quartz(ss) and beta-spodumene(ss), and these were believed to develop with equiaxed and acicular grain morphologies respectively. Silicon oxynitride Si2N2O and X-phase Si3Al6O12N2 formed as minor phases. Nanoindentation was used to assess the hardness and elastic moduli of the Li-Si-Al-O-N materials and both parameters were observed to increase with increasing nitrogen content. Thermal expansion measurements revealed that the low expansion characteristics of mineral derived beta-quartz(ss) and beta-spodumene(ss) were generally retained when nitrogen was introduced into the Li2O-Al2O3-SiO2 system. (C) 1997 The Institute of Materials.