Effect of SiO2 addition on structural and optical properties of Yb:Lu3Al5O12 transparent ceramics based on laser ablated nanopowders

Abstract

Transparent 3.6 at.% Yb:Lu3Al5O12 (Yb:LuAG) ceramics are obtained by solid-state reaction synthesis at 1800 °C in vacuum for 1–5 h using Yb:Lu2O3 and Al2O3 nanopowders (mean size: ∼30 nm) produced by laser ablation and sedimentation. The nanopowders and ceramics are studied by DSC, dilatometry, SEM, XRD, Raman and optical spectroscopy. The effect of the sintering aid (tetraethoxysilane, TEOS, up to 1 wt%, equivalent to 0–0.28 wt% of SiO2 addition) on the micro-structural and optical properties of the ceramics is revealed. With the addition of TEOS, the transparency of the ceramics is improved while the growth of the grains is limited by the SiO2 solubility. For the ceramics sintered at 1800 °C for 5 h with 1 wt% of TEOS, the transmission at ∼1.1 μm is as high as 82.7% and the content of pores is 7 ppm, corresponding to a mean grain size of 14 μm. The ceramics exhibit intense Yb3+ luminescence at ∼1 μm. The maximum stimulated-emission cross-section is σSE = 2.46 × 10−20 cm2 at 1030.2 nm and the luminescence lifetime of the 2F5/2 state is 1.01 ms, close to the radiative one. The synthesized ceramics are promising for thin-disk laser elements.