Structural, optical and dielectric properties of Cobalt incorporated Zinc oxide nanostructures: doping effect of Cobalt

Abstract

This research studies the synthesis of pure (undoped) and Cobalt-doped Zinc oxide nanostructures used the co-precipitation synthesis. Both the Pure and Cobalt-doped Zinc oxide nanostructures exhibit a consistent hexagonal symmetry in their X-ray diffraction (XRD) patterns. Scanning electron microscopy (SEM) micrographs reveal that Zinc oxide, in both its pure and Cobalt-doped forms, appears rod shaped. Energy-dispersive X-ray spectroscopy (EDX) confirms the presence of only zinc and oxygen in pure Zinc oxide samples, while doped samples show the presence of Cobalt, zinc, and oxygen. Fourier transform infrared (FTIR) spectroscopy analysis indicates various stretching vibrations within the Zinc Oxide structure. The calculated band gap energy of pure Zinc oxide is 2.74 eV. While for Zn_0.98Co_0.02O, Zn_0.96Co_0.04O, Zn_0.94Co_0.06O Cobalt doped nanostructures the band gap energies are 2.69 eV, 2.63 eV, and 2.38 eV, respectively. As the number of Cobalt increases, so does the strength of the UV-Vis absorption spectrum. Our samples exhibit a near-band transition when stimulated by a wavelength of 233 nm. A first peak at 398 nm and a second peak at 558 nm in the photoluminescence (PL) spectra signify the presence of defects. High dielectric constant values are obtained using Cobalt-doped Zinc oxide nanostructures, indicating dispersion behavior. The substantial percentage of oxygen vacancies within the Cobalt-doped Zinc Oxide nanostructure results in enhanced electrical conductivity.