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

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 Y2.97Nd0.03Al5O12 and 2% Y2O3 excess Nd: YAG Y2.97Nd0.03Al5O12.2%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.