Effects of Sr²⁺ substitution on photoluminescence characteristics of Ba_1-x-ySr_yZrSi₃O₉:xEu²⁺ phosphors

In this work, single-phase Ba_1-x-ySr_yZrSi₃O₉:xEu²⁺ phosphors were synthesized via the solid-state reaction method. The crystal structure and luminescence properties were investigated using X-ray diffraction and photoluminescence measurements, respectively. An increase of the dopant Sr²⁺ increased the emission intensity of the phosphors. The peak intensity of the samples was at y = 0.4 under near-ultraviolet light excitation (397 nm). The wavelength of the emission peaks red-shifts slightly from 477 to 483 nm due to the splitting of the 5d energy level. Sr²⁺ ions have a smaller ionic radius than that of Ba²⁺ ions, and thus the dopant changes the crystal structure, improving the energy transfer efficiency between luminescence centers. More Eu²⁺ solid solubility was found in Ba_0.6-xSr_0.4ZrSi₃O₉:xEu²⁺ phosphors (10 mol. %) than in the host BaZrSi₃O₉ (6 mol. %), which enhanced the emission intensity. In addition, the thermal reliability of the phosphors was studied.