Fabrication and characterizations of highly transparent Tb3Ga5O12 magneto-optical ceramics

Abstract

Terbium gallium garnet (TGG) precursor was synthesized by the co-precipitation method from the mixed solution of terbium and gallium nitrates using ammonium hydrogen carbonate (AHC) as the precipitant. Fine and low-agglomerated TGG powders with the average particle size of 158 nm were obtained by calcining the precursor at 1100 °C for 4 h. Then, TGG transparent ceramics were successfully fabricated by a new two-step sintering method. The TGG ceramics pre-sintered at 1500 °C for 3 h in air and then HIP post-treated at 1550 °C for 3 h under 150 MPa argon gas showed the best optical quality and the in-line transmittance was 80.3% at 1064 nm. The Verdet constant of the TGG ceramic at 633 nm was about 136.8 rad T−1 m−1, which was rather close to that of the commercial TGG single crystal. High transparency and high Verdet constant make it an attractive alternative for the high-power Faraday isolators.