Abstract
Eu3+ doped ZnWO4 phosphors were synthesized via the co-precipitation technique followed by subsequent thermal annealing in the range of 400–1000 °C. The phase, morphology, elemental composition, chemical states, optical absorption, and photoluminescence (PL) of the phosphors were characterized by X-ray diffraction, scanning electron microscopy, dispersive X-ray spectroscopy, X-ray photoelectron spectrometry, diffuse UV–vis reflectance spectroscopy, PL spectrophotometry, and PL lifetime spectroscopy, respectively. It is found that the PL from Eu3+ doped ZnWO4 is tunable through the control of the annealing temperature. Density functional calculations and optical absorption confirm that thermal annealing created intrinsic defects in ZnWO4 lattices play a pivotal role in the color tunable emissions of the Eu3+ doped ZnWO4 phosphors. These data have demonstrated that intrinsic defect engineering in ZnWO4 lattice is an alternative and effective strategy for tuning the emission color of Eu3+ doped ZnWO4. This work shows how to harness the intrinsic defects in ZnWO4 for the preparation of color tunable light-emitting phosphors.
Highlights
In accordance with the standard X-ray diffraction (XRD) data for monoclinic ZnWO4, the diffraction peaks at 15.36◦, 18.68◦, 23.68◦, 24.32◦, 31.10◦, 37.98◦, 49.90◦, and 51.52◦ in Figure 1 can be assigned to the reflections from the (010), (100), (011), (110), (020), (200), (220), and (130) planes of monoclinic
Eu-doped ZnWO4 phosphors were synthesized via the co-precipitation method followed by
By mixing the intrinsic defect emissions from ZnWO4 host with the red emissions from extrinsic defects Eu3+ in the host, the luminescence color of Eu-doped ZnWO4 can be adjusted in a controllable way, from purplish pink through greenish blue to white, through the control of annealing temperature
Summary
Zinc tungstate (ZnWO4 ) is an important technological material having a diversity of applications in scintillators [1], photocatalysts [2], tunable laser host crystals [3], and light-emitting phosphors [4]. Chen et al tuned the color from blue through white to orange by adjusting the concentration of Eu3+ in ZnWO4 nanorods [8]; Zhou et al tuned the photoluminescence (PL) of Eu3+ and Dy3+ doubly ZnWO4 by adjusting the doping concentrations of Eu3+ and Dy3+ in ZnWO4 nanorods [14] This strategy suffers from severe drawbacks and intrinsic limitations that cannot be solved by itself. Intrinsic defect engineering in the crystal lattice of ZnWO4 can provide an interesting solution to the problem on how to tune the emissions from rare-earth doped ZnWO4 when the doping concentration is fixed. Rather than the control of rare-earth concentration in ZnWO4 , this work shows how to harness the defect engineering in ZnWO4 for color tunable emissions
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