Luminescence Studies of rare-earth Ce³⁺ and Dy³⁺ doped SrAl₂O₄ aluminate phosphors

The rare-earth doped Sr_0.96Ce_0.04-xDy_xAl₂O₄ [x = 0.03, 0.02, 0.01] aluminate phosphors synthesized by the high temperature solid-state reaction route are reported in this work. The phosphors under investigation were characterized for the structural and luminescence properties. The structural studies were carried out exploiting X-ray diffraction, Raman scattering technique, and the Fourier transform infrared spectroscopy. The optical study of the phosphors under observation comprises UV–Vis, thermoluminescence, and photoluminescence studies. The XRD results of these materials on analysis revealed that the samples exhibit double phase where dominating phase is that of desired Sr_0.96Ce_0.04-xDy_xAl₂O₄ [x = 0.03, 0.02, 0.01] phosphors with trace of secondary phase arising from unreacted SrCO₃. The Sr_0.96Ce_0.04-xDy_xAl₂O₄ [x = 0.03, 0.02, 0.01] aluminates have acquired the monoclinic phase (P1 21 n) and SrCO₃ was found to have crystalized into the orthorhombic (Pmcn) phase. The characteristic Raman band at around ≈ 460 cm⁻¹ for Sr_0.96Ce_0.01Dy_0.03Al₂O₄ phosphor conveys the monoclinic structure in the sample. The UV–Vis spectral studies revealed the optical bandgap around 3 eV. Thermoluminescence study inferred the optimum intensity for 25-min exposure to the excitation radiation with higher intensity for x = 0.02 (Dy/Ce) concentration. The photoluminescence studies revealed the emission in the blue region for x = 0.03 and 0.02 confirmed from the CIE coordinate values and near red emission in the higher concentrated Ce³⁺ ions.