Energy transfer process in a rare earth (Ce³⁺ , Dy³⁺ , Sm³⁺ )-doped nanocrystalline phosphate phosphor

This work presents the optimized luminescence spectra for the Ce³⁺ ,Sm³⁺ -doped NaSrPO₄ phosphor that was synthesized using a wet chemical method. Ce³⁺ and Sm³⁺ are activator impurities that show spectral splitting bands that corresponds to the d-f and f-f transitions, respectively. These impurity elements shows the characteristics spectral bands when doped with the NaSrPO₄ host lattice. Spectral splitting in the Ce³⁺ excitation band was monitored in the 240-340 nm range, in which the observed bands were located at 269 nm, 292 nm and 321 nm, and emission bands were observed in the broad spectral range 330-430 nm. However, when Sm³⁺ ion was doped in the same host lattice we obtained a characteristic emission band at 590 and 645 nm in the orange-red region, under sharp excitation bands located at 345, 361, 375, and 403 nm respectively. Also, we carried out energy transfer analysis in the Ce³⁺ /Dy³⁺ -doped NaSrPO₄ phosphor. Further crystalline phase and the nanophase nature of the phosphor compound were confirmed using X-ray diffraction and transmission electron microscopy analyses.