Structural, morphological, optical and mechanical studies of annealed ZnO nano particles

The structural, morphological, optical and mechanical properties of Zinc oxide (ZnO) nanoparticles annealed at different temperatures from 500°C to 1000°C with a step
size of 1000C were synthesised from Sol-Gel method. The X-ray diffraction study revealed that ZnO has hexagonal Wurtzite structure. Scanning Electron Microscope(SEM) images of the studied materials possess spherical morphology with
induced porosity due to change in annealing temperature. The computed size of nanoparticles from Transmission Electron Microscopy (TEM) was 21nm. The UVVisible Spectroscopy revealed that the band gap decreased with increase of the
temperature from 3.05eV to 2.82eV. Photoluminescence (PL) spectrum of ZnO nanoparticles shows that oxygen vacancy related defects increased as the temperature increases from 500°C to 800°C and decreased beyond 800°C. The wear
resistance of ZnO nanoparticles is found to increase with increase of temperature owing to the generation of oxygen vacancies. The maximum friction coefficient was assigned to largest grain size.