Effect of TEOS content on microstructure evolution and optical properties of Sm:YAG transparent ceramics

Highly transparent 4.5 at.% Sm:YAG ceramics were fabricated by solid-state reactive sintering using tetraethyl orthosilicate (TEOS) and CaO as sintering additives. The influences of TEOS content on phase formation, microstructure evolution, and optical properties were investigated. The 4.5 at.% Sm:YAG ceramics with 0.3–0.6 wt% TEOS all have a single yttrium aluminum garnet phase after pre-sintering at 1725 °C for 30 h. With TEOS increasing from 0.3 to 0.6 wt%, residual pores were gradually discharged, the Sm:YAG ceramics with 0.5 and 0.6 wt% TEOS showed fully dense microstructure after vacuum sintering at 1725 °C for 30 h. After hot isostatic pressing (HIP) at 1750 °C for 3 h, the average grain size of the final Sm:YAG ceramics increased from 9.5 to 15.8 μm with TEOS increasing from 0.3 to 0.6 wt%, and all the ceramic samples showed uniform microstructures. The 4.5 at.% Sm:YAG ceramics with 0.6 wt% TEOS achieved high in-line transmittance of 83.6% at 808 nm and absorption coefficient of 3.32 cm−1 at 1064 nm, which means it can effectively suppress amplified spontaneous emission and parasitic oscillation.