Tuning the dielectric behavior and energy storage properties of Mn/Co co-doped ZnO

The synthesis of pure ZnO along with nominal Mn and Co co-doping using a time-efficient and cost-effective wet chemical route to explore their detailed dielectric response is reported. Structural investigations revealed the development of hexagonal crystal symmetry of pristine ZnO. When 5% Mn is substituted, a slight decrease in lattice parameters is observed. However, Co doping did not affect the crystal symmetry as well as lattice parameters. The morphological study exposed that Mn and Co incorporation in ZnO significantly affected the shape, size, and distribution of particles. The maximum porosity is noticed when 5% of Mn is doped in pure ZnO. The elemental analysis confirmed the presence of all elements according to their stoichiometric formula. The relatively higher value of the dielectric constant is noticed in the present case while the value of loss tangent is explained based on oxygen vacancies generated during the auto-combustion process. Short-range electron transport is distinguished from long-range on the basis of relaxation peaks present in electric modulus. The effective contribution of conducting grains and insulating grain boundaries in different frequency regimes is explained by their impedance response.