Effect of La2O3 on the microstructure and optical performance of (Tb0.8Y0.2-xLax)2O3 ceramics

(Tb0.8Y0.2-xLax)2O3 transparent ceramics were prepared by using co-precipitation method combined with pressure-less sintering in flowing H2 atmosphere. Microstructure, optical transmittance, elements composition, and Verdet constant of the (Tb0.8Y0.2-xLax)2O3 ceramics were studied. The amount of La2O3 is crucial for the formation of expected transparent (Tb0.8Y0.2)2O3. With increasing content of La2O3, the number of pores and the grain size of as-fabricated (Tb0.8Y0.2-xLax)2O3 ceramics both decrease. When 4 at.% La2O3 is doped, the (Tb0.8Y0.16)2O3 transparent ceramics shows the highest transmittance of 73.3% at 1400 nm wavelength. With holding time increasing from 8 h to 15 h, the average grain size of (Tb0.8Y0.16La0.04)2O3 ceramics gradually increases from 5 μm to 13 μm. The Verdet constant measured at 633 nm is −352 rad/T·m, which is 2.63 times higher than that of TGG. In addition, large-size ceramics with Φ 20 mm × 3 mm and Φ 30 mm × 3 mm were also successfully obtained.