Investigation on structural, optical and dielectric properties of Co doped ZnO nanoparticles synthesized by gel-combustion route

We report the synthesis of Co doped ZnO nanoparticles by combustion method using citric acid as a fuel for 0%, 1%, 3%, 5% and 10% of Co doping. The structural, optical and dielectric properties of the samples were studied. Crystallite sizes were obtained from the X-ray diffraction (XRD) patterns whose values are decreasing with increase in Co content up to 5%. The XRD analysis also ensures that ZnO has a hexagonal (wurtzite) crystal structure and Co2+ ions were successfully incorporated into the lattice positions of Zn2+ ions. The TEM image shows the average particle size in the range of 10-20 nm for 3% Co doped ZnO nanoparticles. The energy band gap as obtained from the UV-visible spectrophotometer was found gradually increasing up to 5% of Co doping. The dielectric constants (epsilon', epsilon ''), dielectric loss (tan delta) and ac conductivity (sigma(ac)) were studied as the function of frequency and composition, which have been explained by 'Maxwell Wagner Model'. (C) 2012 Elsevier B.V. All rights reserved.