Sintering parameter optimization of Tb 3 Al 5 O 12 magneto‐optical ceramics by vacuum sintering and HIP post‐treatment

Transparent terbium aluminum garnet (TAG) ceramics were achieved by the vacuum sintering plus HIP post‐treating from the coprecipitated TAG nanoparticles. The influences of vacuum sintering temperature and sintering aid TEOS on the optical quality of the TAG ceramics were studied. The results show that with the increase of sintering temperature, the optical quality of TAG ceramics is improved gradually, and the in‐line transmittance of the TAG ceramics treated at 1720°C for 20 hours under vacuum and then HIP post‐treated at 1700°C for 3 hours under 200 MPa argon gas is 81.6% at 1064 nm. The sintering additive TEOS can improve the optical quality of TAG ceramics and inhibit the valence state change of Tb 3+ ions to Tb 4+ during the annealing process. The Verdet constant of the TAG ceramics at 632.8 nm is about −178 rad·T −1 ·m −1 at room temperature, which is 1.3 times that of the commercial TGG crystals (−134 rad·T −1 ·m −1 ).