Photoluminescence properties of Eu³⁺-doped BaY₂ZnO₅ phosphors under near-ultraviolet irradiation

Eu³⁺ ion-doped BaY₂ZnO₅ phosphors were synthesized using a vibrating milled solid-state reaction. The phosphors exhibit a series of Eu³⁺ ion intra-4f excited state ⁵D_J (J = 3, 2, 1, 0) transitions under an excitation of 395 nm. The maximum photoluminescence intensity for ⁵D₀ → ⁷F₂ transition (625 nm) was obtained at a Eu³⁺ ion concentration of 40 mol%; quenching occurred at higher concentrations. The critical distance (R_c) for the ⁵D_J (J = 3, 2, 1) → ⁷F₁ transition was 18.1 Å, which is longer than that of 6.67 Å for the ⁵D₀ → ⁷F₂ transition, indicating that ⁵D_J (J = 3, 2, 1) is easier for concentration quench because of the cross-relaxation mechanism. The red emission of the BaY_1.6Eu_0.4ZnO₅ phosphor has CIE chromaticity coordinates of (0.66, 0.34), which are close to the NTSC system standard red chromaticity (0.67, 0.33). BaY_1.6Eu_0.4ZnO₅ may thus be potentially applicable as a red phosphor for ultraviolet light-emitting diodes converted in solid-state lighting technology.