Fabrication of Dy2O3 Transparent Ceramics by Vacuum Sintering Using Precipitated Powders

As a kind of promising material for a Faraday isolator used in the visible and near infrared range, Dy2O3 transparent ceramics were prepared by vacuum sintering from the nano-powders synthesized by the liquid precipitation method using ammonium hydrogen carbonate as precipitant with no sintering aids. The synthesized precursor was calcinated at 950 degrees C-1150 degrees C for 4 h in air. The influences of the calcination temperature on the morphologies and phase composition of Dy2O3 powders were characterized. It is found that the Dy2O3 powder calcinated at 1000 degrees C for 4 h is superior for the fabrication of Dy2O3 ceramics. The Dy2O3 transparent ceramic sample prepared by vacuum sintering at 1850 degrees C for 10 h, and subsequently with air annealing at 1400 degrees C for 10 h, from the 1000 degrees C-calcined Dy2O3 powders, presents the best optical quality. The values of in-line transmittance of the optimal ceramic specimen with the thickness of 1.0 mm are 75.3% at 2000 nm and 67.9% at 633 nm. The Verdet constant of Dy2O3 ceramics was measured to be -325.3 +/- 1.9 rad/(T center dot m) at 633 nm, about 2.4 times larger than that of TGG (Tb3Ga5O12) single crystals.