Effects of Sintering Aids (Y 3+ , La 3+ and Mg 2+ ) on the Optical Transmittance of Translucent Alumina Ceramics

Translucent Al2O3 ceramics were prepared by vacuum sintering using Y3+, La3+ and Mg2+ as sintering aids which were introduced via chemical precipitation. Effects of the sintering aids on microstructure, relative density and optical transmittance of the translucent Al2O3 ceramics were investigated. The results show that the sintering aids are homogeneously dispersed in translucent Al2O3 ceramics. The optimal amount of the sintering aid introduced is Mg2+（0.15wt%）, Y3+（0.05wt%） and La3+（0.05wt%）, and the corresponding sample shows the highest total forward transmittance（above 80% in the wavelength range of 350–800 nm）. Moreover, the addition of Y3+ could promote grain growth and decrease porosity, thus the optical transmittance of the translucent Al2O3 ceramics is enhanced.