Analysis of electrical properties using complex impedance spectroscopy in solid solutions (PbTiO₃)_0.97-(LaFeO₃)_0.03 prepared by sol-gel technique

The AC complex impedance spectroscopy technique was utilized to extract electrical parameters in (PbTiO₃)_0.97-(LaFeO₃)_0.03 ceramic in wide ranges of frequencies and temperatures. The sample was prepared by sol-gel process and the single phase was confirmed using x-ray diffraction. The compound exhibits high dielectric constant (ε_{r max} ~ 6050) for 1 kHz and low dielectric losses (tanδ < 0.1), diffuse phase transition at Curie temperature of 373 °C, and relaxer behavior. Simultaneous analysis of impedance, modulus, and electrical conductivity was performed. Complex impedance plots show semicircular arcs described by an electrical equivalent circuit which was proposed to explain the impedance results. Off-centered semicircular impedance plots show that the sample obeys to a non-Debye relaxation process. The decrease of resistance, with increasing temperature, indicates a negative temperature coefficient of resistance. Both activation energies, calculated from the conductivity 0.588 eV and the relaxation time 0.49 eV, were comparable highlighting that the relaxation process and conductivity have the same origin.