Investigation of the conduction mechanism, high dielectric constant, and non-Debye-type relaxor in La0.67Ba0.25Ca0.08MnO3 manganite

Abstract

The conduction mechanism and electric properties of La0.67Ba0.25Ca0.08MnO3 (LBCM) were analyzed depending on temperature and frequency. The frequency dependence of electrical conduction plot was explained by the jump relaxation model. The electrical conduction process was based on both theoretical conduction models assigned to the Correlated Barrier Hopping and Non-overlapping Small Polaron Tunneling mechanism. The impedance plot studies reveal that the relaxation is a non-Debye poly-dispersive pattern in the LBCM. This compound has excellent dielectric properties such as the dielectric permittivity exceeding 105 at room temperature, i.e., colossal permittivity, and is one of the highest values recorded for ceramic capacitors. Thus, evolution of dielectric permittivity, described in terms of spatial charge polarization based on Koop's phenomenological theory and Maxwell–Wagner's (M– W) model and high dielectric response, has been driven by barrier layers into the grain boundaries and blended structures of Mn3+/Mn4+. The relaxation processes were examined with modulus, impedance formalism, and electrical conductivity. In the thermal analysis, the relaxations mechanism are related oxygen vacancies.