Fabrication and properties of Bi‐doped Gd ₃ Fe ₅ O ₁₂ infrared‐transparent ceramics with high magneto‐optical effect

Abstract A series of Bi‐doped gadolinium iron garnet (Bi:GdIG) infrared‐transparent ceramics were fabricated by a hot‐press sintering process. The effects of Bi doping on the phase structure, microstructure and optical transmittance of GdIG ceramics were analyzed systematically. The grain size of Bi x Gd 3‐ x Fe 5 O 12 ( x = 0, 0.3, 0.6, 0.9) ceramic samples gradually decreased with the increase of Bi doping, and their optical transmittance gradually decreased, reaching about 70.7%, 62.9%, 56.9%, and 29.8% at 1550 nm, respectively. Meanwhile, the effects of Bi doping on the magnetic and magneto‐optical properties of GdIG ceramics were investigated systematically. The saturation specific Faraday rotation angles ( θ F ) of the Bi x Gd 3‐ x Fe 5 O 12 ceramic samples reached about 51, −266, −595, and −968 deg./cm, respectively, which increased linearly with the increase of the Bi doping amount. The θ F increased by about 34 deg./cm for each 1 at% increase in the Bi doping amount, achieving comparable magneto‐optical properties with Bi:GdIG single crystals produced by liquid phase epitaxy. It shows the bright prospects of Bi:GdIG ceramic materials in the field of magneto‐optical applications.