Generalized Lorentz model description of electrical, dielectric, conductive and magnetic processes two-time relaxations in BaTiO3 ceramics with constitutive relations

Abstract

In this study, generalized Lorentz model is considered in the framework of dielectric, conductive and/or magnetic responses of materials. Beside positive temperature coefficient of resistivity (PTCR) materials (current stabilizers, time delay circuits and current limiters for overvoltage or overcurrent protection, temperature sensors, self-heating, …), magnetic properties indicate to multifunctional or specific applications (for example, nanocubic technologies). AC conductivity studies of various BaTiO3 ceramics or similar ceramics produced equivalent circuits with impedance spectra, usually within the framework of RCPE elements serial connection (CPE - constant phase element) or Cole element. One of the first models that explains PTC effect is the Heywang model, in terms of grain boundaries potential barriers of the Shottky type. Dielectric frequency spectra can be described in similar relationships. However, magnetic features of BaTiO3 ceramics are not well described. In this presentation all three behaviors (dielectric, conductive and magnetic) of materials and their relationships are considered in the case of electric or magnetic alternate fields, which are the basis for experimental measurements.