Two-step glycine-nitrate combustion method for synthesizing lanthanide-doped YAG nanocrystals with adjustable morphology and RGB photoemission

The demand for nanostructured luminescent materials with tunable optical properties and scalable synthesis methods continues to grow due to their relevance in solid-state lighting, displays, and photonic devices. In this study, we report a two-step glycine-nitrate solution combustion method for synthesizing yttrium aluminum garnet (YAG) nanopowders doped with lanthanide ions (Eu 3+ , Tb 3+ , Tm 3+ ) to achieve red, green, and blue (RGB) photoemission. The process involves low-temperature combustion at 300 °C followed by calcination in air at 800–1200 °C. Structural and morphological analysis by X-ray diffraction (XRD) and scanning electron microscopy (SEM) revealed that higher calcination temperatures enhance crystallinity, reduce agglomeration, and lead to the formation of uniform granular morphologies. The optimized temperature of 1000 °C yielded phase-pure YAG with an average crystallite size of 26 nm (Eu 3+ ), 27 nm (Tb 3+ ), and 25 nm (Tm 3+ ), as determined by the fundamental parameters approach. Energy-dispersive X-ray spectroscopy (EDX) confirmed a homogeneous distribution of dopants. Photoluminescence measurements demonstrated strong and well-resolved emission peaks at 460 nm (Tm 3+ : 1 D 2 → 3 F 4 ), 543 nm (Tb 3+ : 5 D 4 → 7 F 5 ), and 591 nm (Eu 3+ : 5 D 0 → 7 F 1 ), with chromaticity coordinates corresponding to pure blue, green, and orange-red emission. The PL behavior was closely linked to the structural features of the host matrix, including lattice symmetry, crystallinity, and defect-induced energy states. This work highlights the effectiveness of glycine-assisted combustion as a rapid and versatile route for producing size-controlled, RGB-emitting YAG nanophosphors. The results contribute to the understanding of structure–property relationships in lanthanide-doped oxide systems and demonstrate potential for use in optical and optoelectronic technologies.