Sol-Gel Synthesis and Characterization of Novel Y3−xMxAl5−yVyO12 (M—Na, K) Garnet-Type Compounds

In this study, for the first time to the best of our knowledge, the new garnets Y3−xNaxAl5O12, Y3−xKxAl5O12, Y3Al5−yVyO12, and Y3−xNaxAl5−yVyO12 with various stoichiometric compositions were successfully synthesized by the aqueous sol-gel method. All obtained samples were characterized by X-ray diffraction (XRD) analysis, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX). It was determined from the XRD results that the formation of monophasic Y3−xNaxAl5O12, Y3−xKxAl5O12, Y3Al5−yVyO12, and Y3−xNaxAl5−yVyO12 garnets is possible only at limited doping levels. The highest substitutional level of doped metal was observed for the YAG doped with sodium (x = 1), and the lowest substitutional level was observed for the YAG doped with vanadium (y = 0.05). Furthermore, the obtained FTIR spectroscopy results were in good agreement with the XRD analysis data, i.e., they confirmed that the YAG is the main crystalline phase in the end products. The SEM was used to study the morphology of the garnets, and the results obtained showed that all synthesized samples were composed of nano-sized agglomerated crystallites.