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 Y 2 (CO 3 ) 3 ·2.79 H 2 O undergoes fragmentation and decomposition into isolated quasi-spherical Y 2 O 3 particles upon calcination in air. Highly transparent YAG ceramics were fabricated from the as-synthesized Y 2 O 3 powder and the commercial α-Al 2 O 3 powder by vacuum sintering. Phase transformation, morphology evolution, and sinterability of Y 2 O 3 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.