Effect of Milling Time on Properties of Mechanochemically Synthesized Nano ZnO

Abstract

This paper presents the characterization results of nanocrystalline Zinc Oxide with different crystallite sizes prepared by mechanochemical synthesis. Nano ZnO particles of different crystallite size were synthesized by high energy milling of precursor powders for various periods of time. Diluents were added to the precursor powders to reduce the agglomeration of product phase and to avoid the spontaneous reaction of precursor powders. After the milling process, diluents were selectively leached out using distilled water. X‐ray Diffraction data was used to analyze the crystallite size of the nanoparticles and also to analyze the progress of the chemical reaction during milling process. Crystallite sizes were calculated from the XRD peak broadening using the Sherrer’s formula. Crystallite sizes were seen to increase at a faster rate after 5h of milling where as bellow 5h of milling, little increase was observed. This increase in crystallite size at higher milling time could be attributed to cold welding and solid state diffusion of the nano particles as a result of high energy impacts from ball to powder collision. Scanning Electron Microscope was employed to analyze the particle morphology and size distribution of the nano ZnO powders. Ultraviolet ‐Visible (Uv‐Vis) spectroscope was employed to analyze the optical absorption of the ZnO nano particles.