SYNTHESIS OF NiO NANOPARTICLES AND STUDY THEIR PROPERTIES

Abstract

NiO nanoparticles were synthesized using simple wet chemical method. These nanoparticles were calcinated at different temperatures 300°C-1000°C (S1-S5) and their structural properties were studied using X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM) and Transmission Electron Microscopy (TEM). X-ray diffraction observations and FESEM images of the calcinated NiO samples indicate that the crystallinity and the particles size both were increasing with increase in calcination temperatures. The XRD results confirm the decrease in strain with respect to calcinated temperature. This may be due to the surface effects and defects existed in the samples. TEM results confirm the polycrystalline nature of samples by SAED pattern. The electrical properties of the NiO pellets were examined by four probe method by measuring direct current (DC) conductivities at different temperatures. The activation energy (Ea) decreases from 0.57eV to 0.33eV when pellets annealed from 300°C to 800°C. The conductivity of samples increased with increase in particle size. It is because that electrons felt low resistance during travel due to large grain size. The optical properties were examined by Photoluminescence (PL) spectroscopy. The emission band came out in the visible range. The surface effects dominated the optical characteristics. The magnetic properties were examined by SQUID. The magnetic moment values come out 3.081.tB to 8.07lB from the measurement. The Weiss constant increased with the particle size and overcome the Ned temperature which may be due to the superexchange properties of NiO samples. The samples did not show any superparamagnetic effect at room temperature which may be due to the multidomain nature of particles.