Sol-gel synthesis and study of praseodymium substitution effects in yttrium aluminium garnet Y_3-xPr_xAl₅O₁₂

In this study, praseodymium substituted yttrium aluminium garnet (Y_3-xPr_xAl₅O₁₂; YPrAG (0 ≤ x ≤ 3)) powders were synthesized by an aqueous sol-gel method and investigated. YPrAG samples were characterized by X-ray diffraction (XRD) analysis, solid state nuclear magnetic resonance (NMR) spectroscopy and scanning electron microscopy (SEM). Luminescence measurements of YPrAG samples were performed as well. It was demonstrated, that three phase regions exist depending on the substitutional level of Pr³⁺ in Y_3-xPr_xAl₅O₁₂. The single-phase cubic garnets have formed up to x = 0.30. The mixture of garnet and trigonal perovskite (Y_1-xPr_xAlO₃) phase have formed when x is between 0.45 and 2.00. The perovskite phase was the main crystalline phase with further increasing amount of praseodymium, no garnet structure was observed. The amorphous impurity phases were detected by solid state NMR spectroscopy. Two broad and intense emission bands in the UV region peaked at 325 and 381 nm and several sharp emission bands in the visible region were determined by investigating the luminescence properties of the Y_3-xPr_xAl₅O₁₂ mixed-metal oxides.