Influence of pH Values on the Morphology and Down-Conversion Luminescence Properties of Zinc Tungstate Micro Nano Crystal Synthesized by a Hydrothermal Method

As the raw materials of Na2WO4•2H2O and ZnSO4•7H2O, ZnWO4 micron spheres and nanorods were synthesized with CH3COOH 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 ZnWO4 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 ZnWO4 nanorods synthesized at pH value of 9, 10 and 11 were much stronger than that of ZnWO4 micron spheres synthesized between the pH values of 4 to 8.

Temperature Effects in Up-Conversion Processes of Erbium - Ytterbium Doped Oxyfluoride Silicate Glass

Temperature Effects in Up-Conversion Processes of Erbium - Ytterbium Doped Oxyfluoride Silicate GlassEr3+- Yb3+doped oxyfluoride glass has been synthesized and investigated. It was found that the up-conversion spectrum of the sample excited by a 980 nm laser diode is highly dependent on the temperature of the sample. Using fluorescence intensity ratio technique the green up-conversion emissions at 525 nm and 550 nm were studied in detail in the temperature range 120-600 K. The potential applicability of the obtained results in the field of the temperature sensing is discussed.