EDTA-mediated morphology and tunable optical properties of Eu³⁺-doped NaY(MoO₄)₂ phosphor

Uniform and well-crystallized NaY(MoO₄)₂: Eu³⁺ 3D hierarchical flower-like architectures self-assembled from different building blocks have been successfully synthesized by a facile ethylene diamine tetraacetic acid (EDTA)-mediated hydrothermal route. The crystalline phase, size, morphology, and down-conversion luminescence properties were systematically characterized using powder X-ray diffraction, field emission-scanning electron microscopy, photoluminescence (PL) and photoluminescent excitation spectra (PLE), respectively. It was found that the pH value in the initial solution was responsible for the crystal phase determination of final products. The experimental results showed that the amount of EDTA was a key parameter which not only determined their spacial arrangement, but also affected the down-conversion luminescence intensity of the final products. In PL spectrum, a prominent red emission was observed due to the hypersensitive ⁵D₀ → ⁷F₂ transition, and the optimum doping level of Eu³⁺ was 20 %. Two strongest lines at 396 and 467 nm in excitation spectra of these phosphors matched well with the two popular emissions from near ultraviolet and blue GaN-based LEDs, so they could be explored for an efficient red region for white light-emitting diodes.