Fabrication and characterizations of Tb ₃ Al ₅ O ₁₂ ‐based magneto‐optical ceramics

Abstract Transparent terbium aluminum garnet (TAG)‐based ceramics were fabricated by vacuum pre‐sintering and hot isostatic pressing (HIP) posttreatment from the co‐precipitated TAG powders with different stoichiometric ratios. After component optimization, the transparent ceramics with TAG single‐phase and attractive optical quality were obtained. The in‐line transmittance of optimal Tb _{(1+ x )3} (Al _0.996255 Si _0.003745 ) ₅ O _{12.0093625+3 x /2} ( x = −.004, −.002) ceramics (1.7‐mm thick) pre‐sintered at 1700°C for 20 h with HIP posttreatment at 1700°C for 3 h under 176‐MPa Ar reaches 82.6% at the wavelength of 1064 nm. With increasing terbium components, the secondary phase TAP appears in ceramics, which significantly degrades the optical quality of TAG‐based ceramics. The Verdet constant of the TAG‐based ceramics at 632.8 nm is about −181 rad T ⁻¹ m ⁻¹ at room temperature, which is about 33% higher than that of the TGG single crystals (−134 rad T ⁻¹ m ⁻¹ ).