Fabrication of YAG transparent ceramics using carbonate precipitated yttria powder

Well-dispersed yttria nanopowders were synthesized by a precipitation method from yttrium nitrate solution using ammonium hydrogen carbonate as a precipitant. Needle-like precursor Y2(CO3)3·2.79 H2O undergoes fragmentation and decomposition into isolated quasi-spherical Y2O3 particles upon calcination in air. Highly transparent YAG ceramics were fabricated from the as-synthesized Y2O3 powder and the commercial α-Al2O3 powder by vacuum sintering. Phase transformation, morphology evolution, and sinterability of Y2O3 powders, microstructure and optical properties of YAG ceramics were investigated in detail. The densification, grain growth, linear shrinkage and phase transformation of the as-sintered ceramics were also explored. The activation energy for grain growth in the ceramic sample is 881 kJ/mol. With optimized preparation conditions, YAG ceramics with the average grain size of about 20 μm were fabricated by sintering at 1780 °C for 20 h, whose in-line transmittance reached 83.7% and 80.3% at the wavelength of 1064 nm and 400 nm, respectively.