Hydrothermal synthesis and optical properties of hexagonal tungsten oxide nanocrystals assisted by ammonium tartrate

Authors

  • Hua-Feng Pang,

    1. Department of Applied Physics, University of Electronic Science and Technology of China, Chengdu 610054, P. R. China
    Search for more papers by this author
  • Xia Xiang,

    Corresponding author
    1. Department of Applied Physics, University of Electronic Science and Technology of China, Chengdu 610054, P. R. China
    2. International Center for Material Physics, Chinese Academy of Sciences, Shenyang 110015, P. R. China
    • Phone/Fax: +86 8320 2130
    Search for more papers by this author
  • Zhi-Jie Li,

    1. Department of Applied Physics, University of Electronic Science and Technology of China, Chengdu 610054, P. R. China
    Search for more papers by this author
  • Yong-Qing Fu,

    1. Thin Film Center, Scottish Universities of Physics Alliance (SUPA), University of the West of Scotland, Paisley, PA1 2BE, UK
    Search for more papers by this author
  • Xiao-Tao Zu

    Corresponding author
    1. Department of Applied Physics, University of Electronic Science and Technology of China, Chengdu 610054, P. R. China
    2. International Center for Material Physics, Chinese Academy of Sciences, Shenyang 110015, P. R. China
    • Phone: +86 136 7901 2605, Fax: +86 8320 2130
    Search for more papers by this author

Abstract

Crystals of hexagonal tungsten oxides (hex-WO3) have been synthesized using hydrothermal method at 150 °C, assisted by the capping reagent of ammonium tartrate (AT). The XRD and EDX results reveal that the lattice distortion exists in all the samples, possibly due to the defects and the intercalation of the residual sodium ions. Different crystal shapes including plate-like, urchin-like, and particle structures were obtained by varying concentration of AT and pH values in the precursor solution. Beside the absorption action of the equation image and Na+ ions, the capping effect can be reinforced by the hydrogen bonding from the tartrate groups in the crystallization process. The bandgap energies were modulated by the size of the nanostructured hex-WO3 crystals due to quantum confinement effect, which increases from 2.74 to 3.04 eV. Based on the analysis of the photoluminescence and X-ray photoelectron spectroscopy, the enhancement of the blue emission of the nanocrystals is assigned as a result of a complex of the local intercalation of the residual sodium ions and the oxygen vacancies or defects.

Ancillary