Comparative study on dielectric and structural properties of undoped, Mn-doped, and Ni-doped ZnO nanoparticles by impedance spectroscopy analysis

In this work, the results of the structural and dielectric investigation of pure, Mn-doped, and Ni-doped ZnO nanoparticles (NP_s), which have been prepared by simple sol–gel method using zinc acetate as precursor, are studied. The synthesized samples are examined via XRD at 300 K, FE-SEM, FTIR, and μ Autolab/FRA2 impedance spectroscopy techniques. XRD results and calculated lattice parameters of all synthesized samples have revealed that diffraction peaks are well matched to the JCPDS card No. 036-1451. FE-SEM obtained images confirm the formation of NP_s. The FTIR graphs exhibit the characteristics transmittance peaks at 510.01 cm⁻¹, 514.36 cm⁻¹, and 509.43 cm⁻¹ for pure, Mn-doped, and Ni-doped ZnO, respectively. This technique also authenticates the existence of ZnO NP_s and doped ones. The dielectric measurements of all synthesized samples have been done in the ranges of 10⁻³ to 10⁶ Hz. Dielectric investigations reveal that the size of the NP_s and dopant type have a great effect on the dielectric manner of samples. The obtained experimental results exhibit that the dielectric constant, loss tangent, electric modulus, and AC electrical conductivity parameters have intense frequency dependence. AC conductivity increases with frequency increment but decreases with doping, making it a potential option for device applications. In principle, an increment in capacitance and dielectric constants values has caused a decrement in frequency, while on the contrary, frequency increasing exhibits an increment of the AC electrical conductivity and electric modulus values. Finally, the magnetic studies extracted from electrical measurement are investigated.