Effect of cobalt oxide on the densification of yttrium aluminum garnet

The solid state sintering of yttrium aluminum garnet (YAG) without any additive at 1873 K could not be achieved beyond 90% of theoretical density. Higher temperature was not tried to avoid abnormal grain growth in the material. To densify further, cobalt nitrate was added to alumina-yttria stoichiometric mixture in various proportion by solution infiltration method. The samples were sintered at 1873 K in air to achieve full density. The as-sintered microstructure revealed no abnormal grain growth.