E. Darezereshki - Department of Materials Engineering, Shahid Bahonar University of Kerman, Kerman, Iran
A. Behrad Vakylabad - Department of Materials, Institute of Science and High Technology and Environmental Sciences, Graduate University of Advanced Technology, Kerman, Iran
M. Yousefi - Department of Materials Engineering, Shahid Bahonar University of Kerman, Kerman, Iran

ZnO nanoparticles were prepared by direct thermal decomposition of the precursor [contain: Zn۴(SO۴)(OH)۶.H۲O and ZnO] in air for ۱ h at ۸۷۵°C. The pH of the precursor solution was set on ۶ and ۱۱ by the controlled addition of the NH۳•H۲O solution. The as-prepared materials were characterized by X-ray diffraction (XRD), infrared spectrum (FTIR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). According to the analyses, the ZnO nanoparticles were pure with both rod-like and spherical shapes which were synthesized using chloride and sulfate solutions, respectively. Moreover, the average diameter of spherical ZnO synthesized at pH=۶ was around ۸۵±۵ nm, while, in an average, the nanorods had ۹۸۰ nm in diameter and ۲.۲ μm in length. The average nanorods at pH=۱۱ were ۷۶۰ nm in diameter and ۳.۳ μm in length, while the average particle size of spherical particles was around ۱۱۲±۵ nm. The TEM and SEM image showed the morphology of spherical and nanorods particles. The reaction temperature of all steps during the synthesis of ZnO nanopowders shifted to the higher temperature, as the pH of the starting solution increased from ۶ to ۱۱. Due to the simplicity, the present method could be proposed as a convenient way to produce pure ZnO nanoparticles using ZnSO۴ and ZnCl۲ solutions without using any toxic and organic chemicals.

Thermal decomposition, Semiconductor, Phase transformation, Zinc oxide, Chemical synthesis