Structural and vibrational properties of (Gd_0.7Lu_0.3)₃Al₅O₁₂ cubic garnet synthesized with different aluminium sources via co-precipitation method

Gadolinium aluminium garnet (Gd₃Al₅O₁₂) nanopowders, with 30 at% lutetium substitution have been successfully synthesized using the co-precipitation method. Several sources, such as aluminium nitrate or sulphate, have been used to develop the (Gd_0.7Lu_0.3)₃Al₅O₁₂ (GdLuAG) compound via normal and reverse add titration using ammonium hydrogen carbonate (AHC) as a precipitant. Different techniques such as X-ray diffraction, FTIR, Raman scattering, BET and SEM/EDS analysis were performed in this study. The X-ray results confirmed that the garnet compound crystallized in the cubic structure with group space Ia \(\bar{3}\) $\overline{3}$ d. The crystallite sizes of the powders were determined by using Rietveld refinement analyses. The FTIR results of vibrational characteristics exhibit the internal and external bonds of GdLuAG. The He–Ne laser 633 nm Raman spectra showed a response in the second phonon region exhibiting strong fluorescence in the near-infrared (NIR). The GdLuAG internal Raman active mode in the visible range and excited by a 785 nm diode laser were measured. The X-ray, BET and SEM results indicated that aluminium nitrate reverse titration compound calcined at 1150°C is the best homogeneous and uniform sample.