Influence of pH values on the morphology and Down-conversion luminescence properties of zinc tungstate micro nano crystal synthesized by a hydrothermal method

摘要

As the raw materials of Na_2WO_4·2H_2O and ZnSO_4·7H_2O, ZnWO_4 micron spheres and nanorods were synthesized with CH_3COOH as the complexing agent by a hydrothermal method at 180°C for 24h. We analyzed the effect of different pH values in reaction solutions on phase compositions, morphologies and luminescent properties of the ZnWO_4 powders. The as-synthesized products were characterized by XRD and SEM. The down-conversion spectrum was measured with spectrophotometer under the excitation wavelength of 291nm. The results indicated that there was a wide emission peaks at 400～550nm. The luminescent intensities of ZnWO_4 nanorods synthesized at pH value of 9, 10 and 11 were much stronger than that of ZnWO_4 micron spheres synthesized between the pH values of 4 to 8.