Optimization of silicon addition for enhancing transparency of terbium gallium garnet magneto-optical ceramics

Recently, terbium gallium garnet (Tb₃Ga₅O₁₂, TGG) ceramics have attracted significant attention as the primary material for Faraday isolators in high-power laser systems. In this work, TGG precursor was synthesized by the co-precipitation method. Thermal behavior, phase composition, and microstructure characterizations were conducted on the precursor and the TGG powder obtained by calcination. The effects of silicon sintering aids on the transmittance of TGG magneto-optical ceramics demonstrate that adding silicon can significantly enhance the optical transmittance of TGG ceramics. TGG ceramics with an addition of 200 ppm silicon, achieve the optimal in-line transmittance of 80.7 % at 1064 nm and 76.5 % at 633 nm after air annealing at 1100°C, with the Verdet constant of −133.5 rad·T⁻¹·m⁻¹ at 633 nm. Microscopy analyses confirm that the TGG ceramics exhibit neither secondary phases nor significant pores. The in-line transmittance and microstructure of TGG ceramics after annealing in air at 1000°C were also investigated.