Effect of sintering temperature on the transparency and mechanical properties of lutetium aluminum garnet fabricated by spark plasma sintering

Transparent lutetium aluminum garnet (Lu ₃Al ₅O ₁₂, LuAG) was fabricated by reactive spark plasma sintering. The effect of sintering temperature on the crystal phase, microstructure, transparency and mechanical properties of LuAG bodies was investigated. Fully dense and single-phase LuAG bodies were obtained at sintering temperatures 1573-1923K. The average grain size increased from 0.18 to 0.52μm with increasing sintering temperature from 1573 to 1773K, and grain growth became significant at 1823K. Transmittance showed a maximum value of 77.8% at 2000nm at a sintering temperature of 1773K after annealing at 1423K in air for 43.2ks. The Vickers hardness increased from 14.2 to 17.2GPa with decreasing grain size from 7.45 to 0.23μm.