Investigation of synergistic effects of cobalt doping on physical and dielectric properties of copper oxide nanoparticles

Cobalt-doped copper oxide nanoparticles were synthesized using the composite hydroxide-mediated (CHM) method, and their structural, compositional, dielectric, and impedance properties were investigated. X-ray diffraction analysis revealed a monoclinic crystal structure for all prepared samples with increasing cobalt concentrations leading to a decrease in crystallite size from 44.34 nm to 33.80 nm. The vibrational bands of the different atoms present in these nanoparticles were estimated using Fourier transform infrared spectroscopy. Scanning electron microscopy indicated a predominantly spherical morphology with decreasing particle size upon cobalt doping. Energy-dispersive X-ray spectroscopy verified the elemental composition of the nanoparticles. The dielectric analysis revealed increasing trend in the values of capacitance from 2.19 × 10⁻¹² F to 1.16 × 10⁻¹⁰ F, real part from 3.74 to 1.99 × 10², imaginary part from 5.16 to 6.20 × 10³, and tangent loss from 1.37 to 5.60. These parameters got maximum values in low frequency regime as the cobalt replaced copper oxide nanoparticles while these parameters decreased with increasing frequency due to interfacial polarization. Moreover, ac-conductivity revealed increasing values from 2.87 × 10⁻⁷ to 3.45 × 10⁻⁴ (Ωm)⁻¹ as the cobalt replaced copper oxide nanoparticles in high frequency regime. Both the real and imaginary parts of impedance revealed trends from 3.60 × 10⁷ Ω to 4.59 × 10⁴ Ω and −2.51 × 10⁷ Ω to −1.44 × 10³ Ω, respectively, when the cobalt replaced copper oxide nanoparticles. These results revealed that the doping of Co altered the structural and dielectric properties of CuO nanoparticles to making them functional for storage devices.