Fabrication of transparent Ce3+-doped (Gd,Lu)3Al5O12 ceramics by two-step spark plasma sintering

Transparent Ce3+:(Gd,Lu)3Al5O12 with microstructure control were fabricated by two-step spark plasma sintering. In the two-step profile, the heating rate was changed from 50 to 5°C/min at the first-step temperatures. During the initial stage of shrinkage, the holding time of the first step sintering could induce densification by suppressing the microstructure coarsening. As compared to the single-step profile, the two-step profile showed smaller grain size, which decreased with a decrease in the first-step temperature. The porosity of the two-step profile was lower than that of the single-step profile, and the lowest porosity was obtained at the first-step temperature of 1000°C, which was the starting point of shrinkage. The TS-1000 specimen showed the highest transmittance among all the specimens because of the microstructure control
offered by the two-step profile. Thus, by employing the two-step profile, the transmittance could be increased from 50.1% (SS-1250) to 56.5% (TS-1000).