Solvothermal Synthesis And Luminescence Property Study Of Rare Earth Europium Ions Doped Zn₂（OH）₃VO₃（Zn₃（OH）₂V₂O₇·2H₂O） Nanocrystals

Vanadates have high research values and application prospects as the matrix of the rare earth ions doped luminescent materials due to their peculiar structure. They can be used as light-conversion materials to improve the utilization ratio of solar energy. In this paper, Zn₂（OH）₃VO₃:Eu³⁺ and Zn₃（OH）₂V2_O7·2H₂O were successfully obtained by hydrothermal and solvothermal method as the raw materials of Na VO3 and Zn（NO3）2·6H2O. The microstructures and optical properties of the samples were characterized by X-ray powder diffraction（XRD）, scanning electron microscopy（SEM） and fluorescence spectrometer（PL）. By optimizing the reaction conditions in different systems, Zn₂（OH）₃VO₃:Eu³⁺/ Zn₃（OH）₂V2_O7·2H₂O light-conversion nanomaterials with controllable morphology and high luminescent performance were obtained. The main results we get were as follows:1. Solvothermal synthesis of Zn₂（OH）₃VO₃:Eu³⁺ nanocrystals with different morphologiesThe synthesis conditions of Zn₂（OH）₃VO₃:Eu³⁺ nanocrystals with different morphologies were optimized through systematically studying the effect of the p H values, the reaction temperature, the reaction time, the volume ratio of ethanol-water, the ratio of ethylene glycol-water on the microstructure and optical properties of the products. Under the excitation number of 330 nm, all products have the red emission around 613 nm.（1） Solvothermal synthesis of sheet Zn₂（OH）₃VO₃:Eu³⁺ nanocrystals using ethanol as the solventThe optimized synthesis conditions of sheet Zn₂（OH）₃VO₃:Eu³⁺ nanocrystals which have the side-length of 150 to 200 nm,and the thickness of 15 to 20nm: the p H value of reaction system was 9, the ratio of ethanol-water was 2, the reaction time was 16 h and the reaction temperature was170℃.（2） Solvothermal synthesis of ball-shaped Zn₂（OH）₃VO₃:Eu³⁺nanocrystals using ethylene glycol as the solventThe optimized synthesis conditions of ball-shaped Zn₂（OH）₃VO₃:Eu³⁺ nanocrystals which have 4 to 8 μm in diameter: the p H value of reaction system was 6, the ratio of ethylene glycol-water was 1.5, the reaction temperature was 170℃ and the reaction time was 24 h.（3） In the comparison to the fluorescence intensities of Zn₂（OH）₃VO₃:Eu³⁺ nanocrystals with different morphologies: ball-shaped Zn₂（OH）₃VO₃:Eu³⁺ nanocrystals > sheet Zn₂（OH）₃VO₃:Eu³⁺nanocrystals.2.Solvothermal/hydrothermal synthesis of Zn₃（OH）₂V2_O7·2H₂O nanocrystals with different morphologiesThe optimized synthesis conditions of Hexagonal Zn₃（OH）₂V2_O7·2H₂O nanocrystals were obtained by studying the effect of the p H values, the ratio of n(C₂O₄^2-)/n(Zn²⁺), the reaction temperature and the volume ratio of ethanol-water on the microstructures and optical properties of the products. Under the excitation number of 330 nm, the red emission around 619 nm are obtained for the products.（1）Solvothermal synthesis of hexagonal sheet Zn₃（OH）₂V2_O7·2H₂O nanocrystals using ethanol as the solvent:The optimized synthesis conditions of hexagonal Zn₃（OH）₂V2_O7·2H₂O nanocrystals were as follows: the p H value of reaction system of 9, the n(C₂O₄^2-)/n(Zn²⁺) ratio of 1:5.5, the ethanol-water volume ratio of 1:1, the reaction temperature of 80℃ and the reaction time of 16 h.（2）hydrothermal synthesis of flower ball shaped Zn₃（OH）₂V2_O7·2H₂O nanocrystals;The optimized synthesis conditions of flower ball shaped Zn₃（OH）₂V2_O7·2H₂O nanocrystals were as follows: the p H value of 8, the PVP dosage of 0.1g, the CTAB dosage of 0.2g, the reaction temperature of 50℃ and the reaction time of 16 h.Flower shaped Zn₃（OH）₂V2_O7·2H₂O nanocrystals were assembled by leaves with an thickness of 50 nm and a mean diameter of 0.4μm.（3） In the comparison to the fluorescence intensities of Zn₃（OH）₂V2_O7·2H₂O nanocrystals with different morphologies: flower ball shaped Zn₃（OH）₂V2_O7·2H₂O nanocrystals > Hexagonal sheet Zn₃（OH）₂V2_O7·2H₂O nanocrystals;3.The fluorescence intensity of Zn₃（OH）₂V2_O7·2H₂O nanocrystals various morphologies was larger than that of Zn₃（OH）₂V2_O7·2H₂O nanocrystals, and ball shaped Zn₂（OH）₃VO₃:Eu³⁺ nanocrystals in a diameter of had the most intense emission, which was about 1.7 times than that of flower ball shaped Zn₃（OH）₂V2_O7·2H₂O nanocrystals.