Ni dependent structural, optical and electrical properties of CuO nanostructures

The present work reports the synthesis of Cu1-xNixO (x = 0%, 3%, 6% and 9%) nanoparticles by co-precipitation method and correlates the effect of nickel on structural, optical and electrical properties. A phase separation into cubic NiO was observed at the higher nickel concentration of 9%. The difference in ionic radii between copper and nickel resulted in the lattice contraction. The mean crystallite size and strain values were found to be varying with respect to nickel concentration. Raman spectroscopy studies exhibited the emergence of 1LO peak on 9% doping due to the phase separation into NiO. The band gap energy calculated using diffuse reflectance spectra indicated a narrowing of band gap with the increase in nickel content. AC impedance measurement showed a maximum conductivity of 2.13 x 10(-2) S/cm at 600 degrees C for Cu(0.94)Nio(0.06)O. Further, a lower activation energy was noticed for 6% which increased at 9% Ni presence. The dielectric constant was found to be increasing till 6% and decreases with higher nickel content (9%). The present work clearly demonstrates the beneficial role of nickel in the form of a doped structure while it becomes detrimental upon phase separation.