Citric sol–gel synthesis and luminescence characteristics of Ca_1−ySr_yLa_2−xEu_xZnO₅ phosphors

The emission-tunable CaLa_2−xEu_xZnO₅ phosphors were synthesized by citric sol–gel method. The products were characterized by X-ray diffractometer, scanning electron microscope, energy dispersive spectroscopy and photoluminescence spectrometer. Through adjusting the dopant concentration of Eu³⁺ in CaLa₂ZnO₅ phosphor, blue-green to orange-red emission with the 467 nm excitation could be obtained, which matches well with the emission of blue LED chip. Luminescence properties of Ca_1−ySr_yLa_1.9Eu_0.1ZnO₅ (0 ≤ y ≤ 1) indicated that increasing Sr²⁺ content enhances not only the emission intensity of ⁵D₀ → ⁷F₂ transition but also the emission intensity ratio of ⁵D₀ → ⁷F₂ to ⁵D₀ → ⁷F₁ (asymmetry ratio). The Ca_0.6Sr_0.4La_1.9Eu_0.1ZnO₅ phosphors possess optimal integrated emission intensity, which is 20 % higher than that of CaLa_1.9Eu_0.1ZnO₅ phosphors, and the Commission International de L’Eclairage chromaticity coordinate is (0.658, 0.341). Ca_1−ySr_yLa_2−xEu_xZnO₅ phosphors may have potential applications in field emission displays based on their particle size, low-cost synthetic route, and diverse luminescent properties.