Fabrication, characterization, and luminescent properties of Y2WO6: Gd3+, Dy3+ hierarchical microspheres
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A series of monodisperse Y2WO6: Dy3+, Gd3+ hierarchical microspheres were synthesized via a facile surfactant-assisted hydrothermal method followed by heat treatment. The as-synthesized samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and photoluminescence (PL) spectra. XRD patterns of the samples with Gd3+ codoping exhibit a merging of (− 232) and (232) peaks, indicating the distorted deformation in Y2WO6 host structure. SEM images demonstrate that the Y2WO6: Dy3+, Gd3+ microspheres are well-dispersed and assembled by many irregular nanoparticles. Upon ultraviolet (UV) excitation at 291 nm, the emission peaks of Dy3+ ions is observed at 480 nm (blue), 579 nm (yellow) and 669 nm (red), corresponding to the characteristic transitions of 4F9/2 → 6H15/2, 4F9/2 → 6H13/2 and 4F9/2 → 6H11/2 of Dy3+, respectively. The optimal PL intensity was obtained in Y2WO6: 2.5 mol% Dy3+ microspheres which can be further enhanced with the codoping of Gd3+. The strongest luminescence is achieved at Gd3+ concentration of 40 mol% with a quantum yied (QY) of 34.45%. In addition, the thermal stability of the sample was also investigated. The CIE of the investigated samples exhibit little change by varying the concentration of Gd3+ ions. The calculated CIE values are all around (0.37, 0.38) and located at the white region, suggesting that the Y2WO6: Dy3+, Gd3+ microspheres could be used for white LEDs.
This work was supported by the grant of Six Major Talent Peak Expert of Jiangsu Province (Grant Nos. R2016L01, 2015-XXRJ-014) and the National Science Foundation of China under Grant No. 11474167.