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 alpha-Al2O3 and Y2O3 powders with tetraethoxysilane (TEOS) and MgO as sintering aids. Pressed samples were sintered from 1500 degrees C to 1750 degrees 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 mu m was obtained by vacuum sintering at 1730 degrees 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 degrees C for 20 h, whose average grain size was about 22 mu m. These pure YAG ceramics can be used for optical windows applications. (C) 2014 Published by Elsevier B.V.