Highly transparent Nd-doped yttria ceramics fabricated by hot pressing with ZrO2 and La2O3 as sintering additives

Highly transparent Nd-doped yttria ceramics were fabricated by hot-pressing at 1600 °C with single addition and co-addition of ZrO2 and La2O3. The binary additives were found to promote the densification of yttria more effectively than single addition, resulting in higher transmittance. The highest transmittance was obtained in the sample with 1 at.% ZrO2 and 3 at.% La2O3, which reached 74.3% transparency at a wave length of 400 nm and 81.3% at 1100 nm. The optical absorption, luminescence, and fluorescence decay of this sample was investigated. The absorption cross-sections of the sample at 806 nm and 820 nm were 1.22 × 10−20 and 1.31 × 10−20 cm2, respectively. The strongest emission was measured at 1078 nm with a full-width at half-maximum of 5 nm with excitation at 808 nm and a fluorescence lifetime of 423 μs. Additionally, the microhardness of the all samples is ranging from 7.88 to 7.05 GPa with variation of the grain size from 0.85 to 1.81 μm, while the fracture toughness of the all samples is about 1 MPa m1/2 and was found to be almost unchanged. These results have demonstrated that Nd-doped yttria ceramics for the application of laser gain media can be fabricated by hot-pressing.