Synthesis of indium tin oxide nano-polycrystalline powders by ultrasonic spray pyrolysis

Indium tin oxide (ITO) nano-polycrystalline powders were prepared by ultrasonic spray pyrolysis (USP) method using a precursor solution of indium and tin chlorides in a simple one-step process without any post-heat treatment, additives and other complex operations. The morphology and crystal structure of ITO powders were studied by thermogravimetric and differential thermal analysis (TG–DTA), X-ray diffraction (XRD), energy-dispersive spectrometer (EDS), scanning electron microscopy (SEM), laser particle size analyzer (LPSA), transmission electron microscope (TEM), high-resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED), respectively. The results indicate that pure cubic ITO solid solution could be obtained at and above the pyrolysis temperature of 600 °C. Through adjusting the size of atomized precursor droplets, the particles with regular spherical shape and smooth surface are also obtained. The spherical particles have a narrow size distribution with a dominant diameter size in the range of 0.52–1.28 μm, and the average value is 1.01 μm. The clear lattice fringes in HRTEM image confirm a polycrystalline structure of ITO particles with the growth direction along (222) direction.