MgO assisted densification of highly transparent YAG ceramics and their microstructural evolution

In current study, various amounts of MgO single dopant was adopted to fabricated high quality transparent YAG ceramics, by utilizing a simple one-step solid state reaction sintering method in vacuum. At a MgO doping amount of only 0.03 wt.%, YAG transparent ceramics with a transmittance of 84.5% at 1064 nm could be obtained, after sintering at 1820 °C for 8 h. The microstructure evolution and optical property of as-fabricated YAG ceramics as a function of MgO doping concentration were systematically investigated. MgO dopant could effectively promote densification of YAG ceramics when the sintering temperature was lower than 1660 °C, and dramatically accelerate its grain growth between 1540 °C and 1660 °C. Further increase the doping amount of MgO would not benefit to the optical quality of YAG ceramics, and the intragranular pores as well as the Mg-riched secondary phase were observed from the MgO heavily doped ceramics.