Temperature Dependence of the Phase Transformation and Photoluminescence Properties of Metastable ZnWO4 Nano-Phosphors with High UV Absorption and VIS Reflectance

摘要

A modified polyacrylamide gel method with tartaric acid, oxalic acid, EDTA, or citric acid used as chelating agent have been applied to synthesize the ZnWO4 nano-phosphors with high UV absorption and VIS reflectance. A metastable ZnWO4 nanophosphor was first observed. The phase structure and physicochemical properties of ZnWO4 nanophosphors showed strong sintering temperature-dependent behavior. The structural characterization confirmed that the metastable ZnWO4 nanophosphor was easily decomposed into ZnO and WO3 under high temperature sintering. Studies on color properties show that the color of ZnWO4 xerogel sintered at different temperatures will change from black to gray to light white and finally to light green. The metastable ZnWO4 nano phosphors have high UV absorption and visible reflection and high blue emission peak at 465 nm with the excitation wavelength of 290 nm. With the increase of sintering temperature, the fluorescence emission intensity of ZnWO4 nano phosphors decreased. The ZnWO4 nano-phosphors prepared by using citric acid as chelating agent and sintered at 900 degrees C is mainly composed of ZnWO4, WO3 and ZnO. The double II band arrangement facilitates the separation of electron and hole pairs in the system, thus reducing the luminescence of ZnO/ZnWO4/WO3 phosphors.

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