Fabrication of transparent neodymium-doped yttrium aluminum garnet ceramics by high solid loading suspensions

Dense neodymium-doped yttrium aluminum garnet (Nd:YAG) transparent ceramic was obtained by slip casting and solid-state reaction. The colloidal behavior of the aqueous suspensions of neodymia, yttria, and alumina mixed powders using Dispex A as dispersant was investigated. The variation in zeta potential due to pH alteration was studied. The isoelectric point (IEP) was at pH 4.5 and 4 for the specimens with and without Dispex A, respectively. The optimal dispersion conditions were achieved for the suspensions at pH 9.6 with 0.4 wt% Dispex A. The green body prepared by slip casting was vacuum sintered from 1200 °C to 1750 °C. The grain size of the sintered body increased, and the pore size decreased with increasing sintering temperature. Pore-free Nd:YAG transparent ceramic with a grain size of 5–10 μm was obtained by sintering at 1750 °C for 10 h. The in-line transmittance of the annealed specimen reached 80.8% at 1064 nm.