In this study, we examined the electrical and dielectric behaviors of cobalt-substituted perovskite \({La}_{0.8}{Ca}_{0.1}{Pb}_{0.1}{Fe}_{1-x}{Co}_{x}{O}_{3}\) \(\left(x=0.00, 0.10, \text{and} 0.20\right)\) materials synthesized via the sol–gel method using the citric acid process and subsequently heat-treated at 900 °C. The crystallographic analysis, carried out by X-ray diffraction, has confirmed an orthorhombic lattice belonging to the Pnma space group. Electrical impedance spectroscopy has been performed within the temperature interval of 150–300 K. The impedance fitting using an equivalent circuit, together with M” spectra analysis, has confirmed the presence of two relaxation mechanisms associated with the contributions of grains and grain boundaries, respectively. The investigation of dc electrical conductivity \(({\sigma }_{dc})\) demonstrated that all samples follow the variable-range hopping \((VRH)\) transport mechanism at lower temperatures and the Arrhenius-type behavior at elevated ones. The examination of conductivity, along with the temperature dependence of the Jonscher’s power-law exponent, has revealed the coexistence of both single and double Jonscher responses. For the reference composition \((x=0.00)\) , conductivity follows a single Jonscher’s law between 150 and190 K and a double Jonscher’s law within 200–300 K. In contrast, for \(x=0.10\) and \(x=0.20\) , the conduction obeys a single Jonscher’s law throughout the whole investigated temperature range. The \(ac\) conductivity analysis indicated that the frequency-dependent variation of the exponent \(S ({S}_{1}, {S}_{2})\) suggests that conduction in LCPFCO can be interpreted through three mechanisms: the overlapping large-polaron tunneling \((OLPT)\) model, the non-overlapping small-polaron tunneling \((NSPT)\) model, and the correlated barrier hopping \((CBH)\) model.
Finally, the extracted activation energies exhibited a decrease with increasing cobalt substitution. Importantly, \({La}_{0.8}{Ca}_{0.1}{Pb}_{0.1}{Fe}_{1-x}{Co}_{x}{O}_{3}\) perovskites have also demonstrated promising applications in gas sensing, highlighting their potential for multifunctional electronic devices combining dielectric, electrical, and sensing properties.
