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

Abstract

Uniform and well-crystallized NaY(MoO 4 ) 2 : Eu 3? 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 5 D 0 ? 7 F 2 transition, and the optimum doping level of Eu 3? 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.

NaY(MoO4)2-based nanoparticles: synthesis, luminescence and photocatalytic properties

“…This behaviour clearly revealed the presence of concentration quenching, which is more pronounced than in the Eu-doped system, in agreement with previous reports. 29,28 Page 14 of 22 Dalton Transactions The luminescence decay curves recorded for the Tb 3+ : NaY(MoO 4 ) 2 samples at the characteristic emission of Tb 3+ (540 nm, 5 D 4  7 F 5 ) showed shorter curves with increasing Tb content (Fig. 4d).…”

“…Open This observation suggests the presence of the well-known concentration quenching effect, produced by cross relaxation processes among emitting centers (Eu 3+ ions in this case) which are located close to each other in the NaY(MoO 4 ) 2 crystal structure. 28 To shed more light on the presence of such a phenomenon, we analysed the dynamics of the luminescence by recording decay curves for all Eu-doped samples at the dominant emission wavelength of Eu 3+ (616 nm, 5 D 0 → 7 F 2 transition) (Figure 4d). Although very similar to each other, a close observation of the curves allows observing that they became progressively shorter with increasing Eu content.…”