Effects of pH on the microstructures and optical property of FeWO_4 nanocrystallites prepared via hydrothermal method

摘要

FeWO_4 nanocrystallites were prepared via a hydrothermal process using ferrous ammonium sulfate [(NH_4)_2Fe(SO_4)_2 ? 6H_2O] and sodium tungstate [Na_2WO_4 ? 2H_2O] as raw materials. The as-prepared nanocrystallites were characterized by X-ray diffraction(XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and UV-vis analyses. Results show that pH values significantly influence the phase and morphology of the as-prepared FeWO_4 nanocrystallites. It is easy to obtain pure FeWO_4 nanocrystallites in a wide range of the pH=2-11. The powders display a hexagonal flakes morphology under acidic conditions of pH=2. With the increase of pH, the morphology change from hexagonal flakes into rods. By UV-vis analysis, the optical band gap of the FeWO_4 powders is calculated to be about 2.40 eV.