Effect of Ni doping on the dielectric constant of ZnO and its frequency dependent exchange interaction

Ni doped ZnO powders were synthesized by a simple dissolution followed by precipitation using zinc acetate, nickel acetate and oxalic acid for different atomic percentages of Ni doping. Proper phase formation was confirmed by x-ray diffraction and the compositional analysis was performed by using x-ray photoelectron spectroscopic studies. The frequency dependent dielectric constant of the Ni doped ZnO samples was measured by an LCR meter, and from the dielectric constant versus frequency curve, fitted with the Cole equation, we obtained static and high frequency dielectric constants of the Ni doped ZnO samples. It was observed that both the static and high frequency dielectric constants decreased with increasing percentages of Ni doping in ZnO. A simple theoretical model based on the Penn model has been successfully developed to describe the above-mentioned variation. We have also observed the frequency dependence of the s, p-d exchange interaction and a theoretical calculation has been successfully developed to explain it.