Structural and optical proprieties of doped cobalt oxide: CuxCo3−xO4 (x = 0.0; 0.1; 0.2; 0.4; and 0.6)

Copper cobaltite oxides of formula CuxCo3−xO4 (x = 0.0; 0.1; 0.2; 0.4 and 0.6) were synthesized by hydrothermal conditions using polyethylene-glycol-400 (PEG-400) as surfactant. The as-prepared samples are characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Rietveld fitted patterns confirm the formation of cubic spinel structure with Fd-3m space group. Particle size was determined from the XRD peak broadening analysis. The Cu-doping effect on the structural and optical properties of the copper cobaltite oxides was investigated. Phase purity of CuxCo3−xO4 was confirmed by X-ray diffraction studies. XRD results reveal that the lattice parameters and the theoretical density (dth) were found to increase with Cu-substitution. The direct and indirect band gap energies were found to decrease with increasing Cu-content from 1.72 eV (x = 0) to 1.39 eV (x = 0.6) and from 1.75 eV for x = 0 (Co3O4) to 1.40 eV for x = 0.6 (Cu0.6Co2.4O4) respectively, indicating a red shift trend when the Cu-content increases.