Fabrication and characterization of highly transparent Er:Y2O3 ceramics with ZrO2 and La2O3 additives

In this study, we report highly transparent Er:Y2O3 ceramics (0-10 at% Er) fabricated by a vacuum sintering method using compound sintering additives of ZrO2 and La2O3. The transmittance, microstructure, thermal conductivity and mechanical properties of the Er:Y2O3 ceramics were evaluated. The in-line transmittance of all of the Er:Y2O3 ceramics (1.2 mm thick) exceeds 83% at 1100 nm and 81% at 600 nm. With an increase in the Er doping concentration from 0 to 10 at%, the average grain size, microhardness and fracture toughness remain nearly unchanged, while the thermal conductivity decreases slightly from 5.55 to 4.89 W/m K. A nearly homogeneous doping level of the laser activator Er up to 10 at% in macro -and nanoscale was measured along the radial direction from the center to the edge of a disk specimen, which is the prominent advantage of polycrystalline over single-crystal materials. Based on the finding of excellent optical and mechanical properties, the compound sintering additives of ZrO2 and La2O3 are demonstrated to be effective for the fabrication of transparent Y2O3 ceramics. These results may provide a guideline for the application of transparent Er:Y2O3 laser ceramics.