The effect of temperature on the ac electrical conductivity and impedance spectroscopy of spinel type Li–Mg–Cu mixed ferrites with the compositions \({Li}_{0.5-x}{Mg}_{x}{Cu}_{0.5}{Fe}_{2}{O}_{4}\) (where x = 0.0, 0.2, 0.3, and 0.5) has been reported in this study. X-ray diffraction technique reveals that all the samples have shown the cubic spinel structure. The experimental ( \({a}_{exp})\) and theoretical lattice parameters ( \({a}_{th})\) have been calculated for all the samples. It is observed that both ( \({a}_{exp}\text{ and }{a}_{th})\) increased with increasing Mg content, which could be attributed to a larger ionic radius of Mg2+ compared to Li+. Dielectric constant (ε′), ac electrical conductivity ( \({\sigma }_{ac}\) ) and impedance spectroscopy have been observed at different temperatures (300, 343, 393, 443, and 493 K) as a function of frequency. The dielectric property showed a dispersive behavior following the Maxwell Wagner polarization. The enhancement of ε′ with increasing temperature indicates the semiconducting nature of the studied samples. The variation of \({\sigma }_{ac}\) with the reciprocal of temperature demonstrates that the activation energy in the higher frequency regions is lowered, which is associated with the larger conductivity. The electrical parameters (Rg, Rgb, Cg, Cgb, \({\tau }_{g}\) , and \({\tau }_{gb}\) ) have been calculated from the Nyquist plot. The behavior of the conduction mechanism with temperature shows that non-overlapping small polaron tunneling (NSPT) model is observed for the samples with x = 0.0 and 0.5, while x = 0.2 follows both NSPT and correlated barrier hopping (CBH) model. However, conduction via overlapping large polaron tunneling (OLPT) model is prominent at x = 0.3. The mismatching of the master curves indicates that the relaxation mechanism is temperature dependent.
