Two-step pressure sintering of transparent lutetium oxide by spark plasma sintering

Transparent lutetium oxide (Lu2O3) body was prepared by spark plasma sintering using a two-step pressure profile combined with a low heating rate. The effects of pre-load pressures from 10 to 100 MPa and heating rates from 0.03 to 1.67 K s−1 on the microstructures and optical properties were investigated. With increasing pre-load pressures from 10 to 100 MPa, the grains became smaller with a narrower distribution, whereas the transmittance showed maxima at 30 MPa. The average grain size slightly increased from 0.67 to 0.86 μm as the heating rate increased from 0.03 to 1.67 K s−1, while the transmittance decreased. Transmittances of 60% at 550 nm and 79% at 2000 nm were obtained under a pre-load pressure of 30 MPa at a heating rate of 0.17 K s−1.