Effect of temperature on the electrical properties of lanthanum ferrite

Electric and dielectric properties of lanthanum ferrite were investigated by the alternating current impedance spectroscopy. Results reveal that LaFeO₃ exhibits a non-Debye type relaxation. High values of ε' were obtained at low frequency. Such behavior was explained based on the Maxwell-Wagner polarization model. Furthermore, a low dielectric loss was obtained at high frequencies indicating that the obtained compound is an important candidate for nonlinear optical application. The variation of the AC conductivity with frequency at different temperatures obeys the universal Jonscher's power law. The decreasing trend of the exponent s with temperature increase suggests that the correlated barrier hopping model is adequate to describe the conduction mechanism in LaFeO₃. Furthermore, the density of the localized states N(E_f) at the Fermi level was calculated at different temperatures. Results reveal an increase in N(E_f) with temperature increase. Such behavior explains the observed increase in σ_ac.