Study on the sintering behavior of Y3GaAl4O12 ceramics during pre-sintering and fabrication of highly transparent ceramics

Yttrium aluminum gallium garnet (Y₃(Ga,Al)₅O₁₂,YAGG) based transparent ceramics exhibit promising application potential in the fields of scintillators, white LEDs/LDs and persistent phosphors. However, conventional vacuum sintering induces the evaporation of Ga₂O₃, damaging the compositional homogeneity. This study successfully fabricated the highly transparent Y₃GaAl₄O₁₂ ceramic via sintering the green body prepared from single-phase powder in air followed by hot isostatic pressing. Upon substituting Ga³⁺ for Al³⁺, Y₃GaAl₄O₁₂ ceramic exhibited more obvious grain growth during intermediate stage of sintering, resulting in a higher apparent activation energy for densification (2036 ± 157 kJ/mol). The evolution of microstructure and grain size in the pre-sintered Y₃GaAl₄O₁₂ ceramic were also investigated. Finally, the Y₃GaAl₄O₁₂ transparent ceramic (thickness 2.0 mm) had an in-line transmittance of 77 %@1064 nm, and the refractive index and optical band gap were 1.851 (589 nm) and 5.59 eV, respectively. This study provides a promising strategy to fabricate highly transparent gallium-containing garnet ceramics.