Effects of Gd3+-doping on the fabrication and performances of highly transparent (Lu,Gd)2O3:Eu solid-solution ceramics

By pre-treating and component design of the ceramic powders, cubic (Lu,Gd)(2)O-3:Eu solid-solution ceramics with high optical quality were achieved by the solid-state reaction method combined with vacuum sintering. The effects of Gd3+ doping (x = 0.05-0.6) on powder characteristics, phase compositions, microstructures and optical performances of the (Lu0.95-xGdxEu0.05)(2)O-3 ceramics were systematically investigated to obtain the optimum Gd3+ content. The results indicated that the incorporation of moderate amounts of Gd3+ (5-50 mol%) effectively promoted mass diffusion and grain growth during sintering. The 50 mol% Gd3+-doped Lu2O3:Eu transparent ceramic (using the powder calcined at 1200 degrees C) sintered at 1750 degrees C for 5 h exhibited the optimum transmittance of 77.0 % in the visible spectral region (similar to 1 mm in thickness), which was significantly higher than the reported transmittance of vacuum sintered (Lu,Gd)(2)O-3:Eu ceramics (less than 65.0 %). Owing to the lower electronegativity of Gd3+ relative to Lu3+, the bandgap energies of the final ceramics decreased gradually with increasing Gd3+ substitution, and the redshift of the CTB centre was observed with more Gd3+ addition. Under CTB excitation, the incorporation of Gd3+ enhanced the red emission intensity and shortened the fluorescence lifetime.