Comparative structural, optical, and dielectric studies of Zn_1−xMn_x/2A_x/2O (A = Ni, Co and x = 0.24) nanoparticles

In this manuscript, we report a successful synthesis and characterization of pure ZnO (ZO), Mn/Ni (ZMNO), and Mn/Co (ZMCO) co-doped ZnO nanoparticles which were prepared using low-cost and simple sol–gel auto-combustion method. These nanoparticles were analyzed by X-ray diffraction (XRD) and Fourier-transform infra-red (FTIR) spectroscopy for structural properties, scanning electron microscopy (SEM) along with energy-dispersive X-ray (EDX) spectroscopy for morphological analysis, and UV–Vis and photoluminescence spectroscopy for optical investigations. XRD and FTIR measurements substantiated that each sample is crystallized in the single-phase polycrystalline wurtzite hexagonal geometry of ZnO nanoparticles. The average crystallite size inferred from XRD spectra is found to be in the decreasing order of ~ 39 nm (ZO), ~ 38 nm (ZMNO), and ~ 37 nm (ZMCO), along with a significant reduction in the optical bandgap from 3.26 to 3.04 to 2.86 eV. The SEM images show that the nanostructures in the prepared samples are arranged in an agglomerated spherical patterns, while the EDX spectra signify the presence of Zn, Mn, Ni, Co, and O elements in the synthesized samples with their substantial percentage. The dielectric constant of all samples decline with frequency hence exhibits typical dielectric dispersion. AC conductivity of the samples increased with increasing frequency but decreased while doping.