Transparent Tb3Ga5O12 magneto-optical ceramics sintered from co-precipitated nano-powders calcined at different temperatures

Terbium gallium garnet (TGG) ceramics were fabricated by air sintering and successive HIP post-treating from the TGG nanoparticles synthesized via the co-precipitation technique. The influences of the calcination temperature on the phase and morphology evolution of the nano-powders, as well as the optical transparency and microstructure of the obtained TGG ceramics were investigated in detail. The powders calcined at 1100-1250 degrees C retained the TGG phase purity and displayed significantly less agglomeration. Using the above powders as raw materials, the TGG ceramics pre-sintered at 1500 degrees C for 3 h in air and then HIP post-treated at 1550 degrees C for 3 h under 150 MPa argon gas showed the similar optical qualities and the in-line transmittances were about 70% at 1064 nm. The Verdet constants of all the ceramics were calculated to be about 137 rad T-1 m(-1) at room temperature, which were nearly independent of the optical quality of the ceramics.