Synthesis of tungsten oxide nanoparticles by acid precipitation method

Tungsten oxide (WO3) nanoparticle having average size of 30 nm, and nanoplate having average dimension of 190 ± 15 nm wide and 50 ± 5 nm thick were prepared by controlling a precipitation of ammonium tungstate para pentahydrate with nitric acid. The two nanostructured microstructures were obtained by varying the stirring time during the precipitation reaction while the other synthesis parameters were identical. Phase transition of the WO3 precipitate was investigated by means of thermal analysis and X-ray diffraction, while the microstructure was observed by using a scanning electron microscope and a transmission electron microscope. The effect of the concentrations of the tungstate salt and nitric acid on the rate of precipitation and the percent yield of the precipitating product is also described.