Sol-Gel Processing of Infrared Transparent Mullite

It was shown that infrared transparent, dense mullite can be prepared by using sol-gel processing techniques at temperatures as low as 1,250{degree}C. The molecular structure of the gel and the packing of the particles and particle domains are the key processing parameters that control viscous phase sintering. Heat treatment above 1,280{degree}C depleted the viscous phase through mullite formation, leading to fully dense, crack-free bodies.