Co-precipitation synthesis, structural characterization and fluorescent analysis of Nd³⁺ doped Y₃Al₅O₁₂ and Yb₃Al₅O₁₂ nanocrystallines

Nd³⁺, as one of the most important rare-earth (RE) ion, has been playing a significant role in pumping the infrared (IR) light. Depending on different synthesis strategies, doping content, and crystal lattice, however, Nd³⁺ always shows different IR intensity. In this work, we have fabricated two series of Nd³⁺ doped nanocrystallines that share with the same crystal structure, i.e., Nd³⁺ doped Y₃Al₅O₁₂ (YAG) and Yb₃Al₅O₁₂ (YbAG), through using the co-precipitation synthesis method while the ammonium bicarbonate as the precipitant agent. To reveal the influence of the synthesis conditions (e.g., synthetic temperature and pH value) on structural and florescent properties of Nd³⁺ doped YAG and YbAG nanocrystallines, several techniques have been performed in this work, including the X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric-differential scanning calorimeter (TG-DSC), Fourier transform infrared (FT-IR) spectroscopy, Raman and florescent spectroscopy spectra. Our results reveal that the optimal synthesis conditions are 1000 °C and pH 8 for YAG:Nd³⁺ and 900 °C and pH 9 for YbAG:Nd³⁺. Moreover, we also find the optimal Nd³⁺ doping contents of the YAG:Nd³⁺ and YbAG:Nd³⁺ nanocrystallines are 3% and 1.5%, which correspond to the strongest fluorescent intensity upon excitation at 808 nm and 980 nm, respectively. Typically, we reveal that substitution of Y with Yb ions could allow to enhancing the Nd³⁺ fluorescent intensity upon excitation at 808 nm. This work provides new insights into designing excellent crystal materials that can allow us to realize the laser transparent ceramics.