A useful approach to understand the origin of defects in transparent YAG ceramics

Transparent yttrium aluminum garnet (YAG) ceramics are mostly sintered under vacuum to favor pore closure. However, this may conceal the origin of microstructural defects, complicating process optimization. We describe a useful approach to understand the origin of defects in transparent YAG ceramics: reactive sintering was performed in air at a moderate temperature for a short time. The resulting microstructure allowed to understand the origin of defects in corresponding vacuum-sintered specimens. The porosity of air sintered samples could be related to the presence of aggregates of starting oxide particles, which eventually under vacuum react to form YAG, but leave behind pores