LAUSR

In this research, the Taguchi method with L9 orthogonal array was applied to optimize the experimental parameters used in synthesizing tungsten trioxide, WO3, nanopowders through the simple, fast, and cost-effective sol-gel method. Synthesis parameters, including sodium tungstate and acid concentrations, sodium tungstate to oxalic acid, and sodium tungstate to cetyltrimethylammonium bromide weight ratios were considered as the Taguchi factors. The average size and aspect ratio of WO3 nanoparticles were considered as the characteristic factors. The optimum condition for these factors was introduced using the signal-to-noise ratio analysis. The condition was obtained as follows: sodium tungstate concentration of 0.25 mol/l, acid concentration of 1 mol/l, sodium tungstate to oxalic acid weight ratio of 1:2, and sodium tungstate to cetyltrimethylammonium bromide weight ratio of 1:0.4 for the average particle size; sodium tungstate and acid concentrations of 1 and 3 mol/l, respectively; and sodium tungstate to oxalic acid and sodium tungstate to cetyltrimethylammonium bromide weight ratios of 1:1.5 and 1:0.4, respectively, for the aspect ratio. The concentration of sodium tungstate and its weight ratio to cetyltrimethylammonium bromide were proposed as the main parameters influencing the size and aspect ratio of WO3 nanopowders. Also, under the optimum condition, WO3 nanopowders were prepared, and their structure, as well as chemical composition, were characterized using field emission scanning electron microscope, energy-dispersive X-ray spectroscopy, and X-ray diffraction. Characterizing the final product synthesized under the optimum condition confirmed producing the nanopowder with an average particle size of 47 nm and aspect ratio of 1.22.