Solid-state reactive sintering of YAG transparent ceramics for optical applications

Transparent polycrystalline YAG ceramics were fabricated by solid-state reactive sintering of a mixture of commercial α-Al2O3 and Y2O3 powders with tetraethoxysilane (TEOS) and MgO as sintering aids. Pressed samples were sintered from 1500 °C to 1750 °C in vacuum. Phase transformation, densification, microstructure evolution, grain growth kinetics and optical transparency of YAG ceramics were examined. Fully dense YAG transparent ceramic with average grain size about 17 μm was obtained by vacuum sintering at 1730 °C for 10 h and the in-line transmittance of the sample was 80.9% at 1064 nm wavelength. The maximal transmission 82.8% was demonstrated for the sample sintered at 1730 °C for 20 h, whose average grain size was about 22 μm. These pure YAG ceramics can be used for optical windows applications.