Synthesis of Tb4O7 nanopowders by the carbonate-precipitation method for Tb3Al5O12 magneto-optical ceramics

Tb4O7 nanopowders were synthesized by the precipitation method using ammonium hydrogen carbonate (AHC) as the precipitant. The influence of calcination temperature on the properties of Tb4O7 powders was investigated by FTIR, XRD and FESEM. It is found that 1000 °C is the optimum calcination temperature for Tb4O7 powders used for fabrication of Tb3Al5O12 (TAG) transparent ceramics, and the average particle size of the 1000 °C-calcined powder is about 150 nm. Using the 800 to 1100 °C-calcined Tb4O7 powders as raw materials, TAG transparent ceramics were fabricated by vacuum sintering at 1700 °C for 20 h. The sample sintered from 1000 °C-calcined Tb4O7 powders shows the best transparency, and its in-line transmittance is above 55% in the 500-1480 nm region, reaching 58.3% at the wavelength of 633 nm. The microstructures and the magneto-optical properties of the TAG ceramics sintered from 800 to 1100 °C-calcined Tb4O7 powders were also studied.