Toward vacuum sintering of YAG transparent ceramic using divalent dopant as sintering aids: Investigation of microstructural evolution and optical property

Transparent YAG ceramics were fabricated by solid state reaction sintering using divalent dopants (CaO and MgO) as sintering additives without TEOS doping, and the effects of divalent dopants on their microstructure evolution and optical properties were investigated. It was found that CaO was more effective with respect to inhibiting grain growth than MgO, but not as effective as MgO in promoting densification. Fully dense, transparent YAG ceramics with excellent optical qualities could be achieved by optimizing the doping concentrations of CaO and MgO; the transmittance at 1064 nm was as high as 84.5% for 3 mm thick sample at the molar ratio of Ca: Mg=1:4, after sintered at 1840 °C for 8 h in vacuum.