Gamma irradiation effects on the characteristics of Sm³⁺ doped aluminate phosphors for dosimetry applications

This study investigates the synthesis, optical, and Thermoluminescent properties of orangish-red emitting SrAl₂O₄ phosphors doped with Sm³⁺ ions, prepared via the solid-state reaction technique. The resulting phosphors exhibit a monoclinic crystal structure, belonging to the P2/m space group, as confirmed by X-ray diffraction. Scanning Electron Microscopy (SEM) analysis reveals significant surface agglomeration, while Energy Dispersive X-ray (EDX) spectroscopy validates the composition of the phosphors. Fourier Transform Infrared (FTIR) spectroscopy indicates the presence of various functional groups in the sample. Reflectance spectra reveal a decrease in bandgap on doping. CIE coordinates further demonstrate that the phosphors are appropriate candidates for reddish light-emitting diode (LED) applications since they exhibit emission peaks at 562 nm, 599 nm, and 645 nm under UV excitation, which are associated with green and red emissions. The optimal concentration of Sm³⁺ is 0.9 mol%, beyond which the concentration quenching of luminescence takes place. The SrAl₂O₄: 0.9 mol% Sm³⁺ phosphor displays a linear response to radiation doses ranging from 5 Gy to 25 Gy, with an optimal dose of 10 Gy. The phosphor also exhibits high sensitivity, capable of detecting low doses of radiation. Thermoluminescence (TL) analysis reveals three trap centers with different energies, indicating the potential of these phosphors for use as TL dosimeters. The findings suggest that Sm³⁺-doped SrAl₂O₄ phosphors are promising for both LED and radiation dosimetry applications.