Effect of cerium substitution on structural, optical, electrical transport and magnetic properties of spinel cobaltite synthesized through citrate-nitrate method

The copper cobaltite samples of Cu_1 − xCe_xCo₂O₄ (x = 0, 0.05, 0.1) were synthesized by the simple citrate-nitrate method. The cubic spinel structure of all the synthesized samples was confirmed using X-ray diffraction (XRD). A decrease in crystallite size from 28 nm to 23 nm was observed with the addition of Ce as dopant. A clear variation in lattice parameters was seen, demonstrating the adherence of the synthesized samples to Vegard’s rule. The effect of doping on microstructural parameters like space group, lattice constant (a), volume of the unit cell(a³) and density(ρ) was calculated using Rietveld refinement analysis and the computed results was found well correlated with the experimental one. The FTIR spectra results complemented the spinel structure. Spherical shaped morphology was observed using HR-SEM analysis and element composition was confirmed using EDAX. The optical analysis inferred the occurrence of two optical energy gaps around 1.6 eV and 2.1 eV in all samples. These optical band gaps were found to decrease with Ce³⁺ doping, as indicated by the red shifts in the optical spectra. A decline in the dielectric constant with an increase in AC conductivity was observed in all the samples. Electric modulus and impedance studies elucidated the shift of relaxation peaks at higher frequency domain. The magnetic measurements investigated using VSM indicated the weak antiferromagnetic nature of Cu_1 − xCe_xCo₂O₄. The substitution of cerium reduced the coercivity of Cu_1 − xM_xCo₂O₄ which makes it suitable for magnetic recording media applications. The dielectric and magnetic characteristics confirms that these materials are well-suited for its use in Multi-layer chip inductors (MLCI) circuit applications.