Transparent polycrystalline alumina using spark plasma sintering: Effect of Mg, Y and La doping

ransparent polycrystalline alumina (PCA) is a promising replacement for sapphire. Its optical properties however are highly dependent on the rain size and residual porosity which need to be controlled for real inline transmittances (RIT), that are high enough for possible applications. To achieve high RITs, doping as well as pressure assisted sintering is often used. In this study spark plasma sintering (SPS) and doping are nvestigated. A systematic experimental design is used to study the influence of Mg, Y and La single or co-doping (75–450 ppm) as well as the PS sintering pressure and temperature on the RIT and grain size of PCA. Using optimized sintering parameters, RITs of >50% were attained in the visible wavelength (640 nm) for 0.8 mm thick samples for almost all oping strategies. The best RIT of 57% was for triple-doped samples at a total dopant level of 450 ppm. These results are significantly better than reviously published SPS studies and illustrate that SPS sintered alumina can attain high and reproducible optical transmittances under various oping and sintering conditions. 2009 Elsevier Ltd. All rights reserved.