Influence of non-stoichiometry on solid-state reactive sintering of YAG transparent ceramics

Transparent yttrium aluminum garnet (Y3(1+x)Al5O12) ceramics with different deviations from stoichiometry were fabricated by solid-state reactive sintering of commercial powders. The influence of non-stoichiometry on phase composition, microstructure, grain growth kinetics and optical transparency of the ceramics were studied. It was found that for Al2O3-excess samples, the transmittance and the average grain size decreased sharply due to the Al2O3 secondary phase. For the stoichiometric sample sintered at 1760 °C for 10 h, the highest transmittances of 83.1% at 1064 nm and 80.2% at 400 nm were obtained. For Y2O3-excess samples, when the excessive content was smaller than 0.7 mol%, the transmittance decreased slightly and the average grain size increased. However, when the deviation was larger than 0.7 mol% the transmittance and the average grain size decreased due to the secondary phases.