Combustion Synthesis and Influence of Dy³⁺ ions on Structural and Photometric Attributes of Olivine-type LiMgPO₄ Nanophosphors for Illumination Applications

The low-cost technique of combustion synthesis was used to synthesize the trivalent Dysprosium (Dy³⁺) doped olivine type Lithium Magnesium Phosphate (LiMgPO₄). X-ray diffraction (XRD) analysis verified the orthorhombic phase, corresponding to the space group Pnma. The crystallite size of 50.83 nm was calculated using Debye-Scherre formula. FESEM technique was used to study the morphology of the sample which depicts its porous nature. High-Resolution Transmission Electron Microscopy (HRTEM) analysis provided an average particle size measurement of 65 ± 2.04 nm. The phosphor’s photoluminescence (PL) excitation spectrum revealed distinct peaks in the ultraviolet (UV) and near-ultraviolet (near UV) regions, aligning with the characteristics of Dy³⁺ ions. Four emission peaks were observed in the PL spectra at various wavelengths: ⁴F_9/2→⁶H_15/2 (482 nm), ⁴F_9/2→⁶H_13/2 (578 nm), ⁴F_9/2→⁶H_11/2 (663 nm) and ⁴F_9/2→⁶H_9/2 (700 nm). Near-white light emission was observed at the Commission International de l’Eclairage (CIE) coordinates of Dy³⁺ activated LiMgPO₄ [LMP] phosphor, which were (x = 0.41, y = 0.42) with color purity of 49.20%. The band gap of the prepared phosphor was calculated using diffuse reflectance spectra, yielding a value of 4.47 ± 0.02 eV. The results indicated that the synthesized phosphor had potential for various illumination applications when combined with other phosphors under near-UV stimulation.