Effect of composition deviation on the microstructure and luminescence properties of Nd:YAG ceramics

Abstract

Neodymium-doped yttrium aluminum garnet (Nd:YAG) ceramics with different Al₂O₃/Y₂O₃ deviation levels were prepared using a solid-state reaction-vacuum sintering method. Transparent ceramics were obtained with their composition in between stoichiometric Nd:YAG Y_2.97Nd_0.03Al₅O₁₂ and 2% Y₂O₃ excess Nd:YAG Y_2.97Nd_0.03Al₅O₁₂·2%Y₂O₃. The stoichiometric Nd:YAG ceramic obtains a homogeneous grain microstructure and clean grain boundaries. Non-stoichiometric compositions lead to ceramic microstructures different from that of the stoichiometric Nd:YAG. Nanograins of excess Al₂O₃ remain inside the Nd:YAG grains in Al₂O₃-excess ceramics, while Y-rich compounds recrystallize at the Nd:YAG grain boundaries in Y₂O₃-excess ceramics. Photoluminescence spectra of the sintered ceramics around 808 and 1064 nm were also studied. Peak positions of their luminescence spectra are little affected by composition deviation, while their intensity evidently declines due to the existence of a second phase arising from the composition deviation. The results of this work can contribute toward the controllable synthesis of highly transparent YAG ceramics and further exploration of the Nd ion spectra.