Role of Sm³⁺ ion doping in luminescence and thermal stability performance of LiCdPO₄ nanophosphors

The present study illustrates a comprehensive analysis of Sm³⁺ activated LiCdPO₄ phosphors, using XRD, XPS, FTIR, DRS, and PL analyses, along with thermal stability studies, to explore their potential as efficient luminescent materials for white light-emitting applications. The phosphors were synthesized via a cost-effective solution combustion approach. The XRD analysis confirms that the synthesized phosphors crystallize in a pure orthorhombic phase structure with the Pnma (62) space group. The elemental analysis is characterized by XPS spectroscopy. The FTIR spectra reveal that the characteristic stretching and bending vibrations of the ortho-phosphate group [PO₄]^3- are observed within the 1400-400 cm^-1 range. Furthermore, diffuse reflectance spectra were examined for various Sm³⁺ concentrations to explore the optical performance of the phosphor. Upon UV light excitation, the emission spectra exhibit amber region performance located at 603 nm, attributed to the ⁴G_5/2 → ⁶H_7/2 transition of Sm³⁺ ions, indicating that the activator ions occupy low-symmetry sites in the LiCdPO₄ host lattice. The optimal PL intensity was achieved at a 1 mol% Sm³⁺ doping concentration, yielding CIE color coordinates (0.59, 0.41) with a high color purity of about 90%. Additionally, thermal stability was demonstrated through temperature-dependent emission studies in the temperature range 303-483 K. These results indicate that LiCd_(1-x)PO₄:xSm³⁺ phosphors exhibit promising amber emission and show potential for application as phosphor materials in white light-emitting diodes.