Synthesis and characterization of tungsten trioxide powders prepared from tungstic acids

WO3 powders were prepared by the thermal decomposition of tungstic acids (WO3·nH2O, n=1/3, 1, 2). The tungstic acids were synthesized from WO42− aqueous solutions under a variety of conditions of pH, temperature and W(VI) concentrations. The thermal decomposition of the tungstic acids into WO3 was analysed by TG and DSC methods. Nano-sized WO3 powders with different morphological characteristics were obtained by thermal treatment of the tungstic acids at 500 °C in air atmosphere. The morphologies of WO3 powders were characterised by scanning electron microscopy and infrared absorption spectroscopy. Patterns of infrared spectra were related with distinct powder morphologies.