High dielectric and conduction proprieties of Na+-doped lanthanum Strontium manganite for cathode materials application

Abstract

        In the present work, we were conducted to analyze the structural, conduction and dielectric behavior of the Na⁺-doped Lanthanum Strontium manganite ceramics synthesized using the sol-gel technology over broad temperature and frequency ranges. X-ray diffraction (XRD) at room temperature and Rietveld analysis reveals that La_0.7Sr_0.2Na_0.1MnO₃ crystallizes in a pure phase belonging to the rhombohedral structure with R-3c space group. Moreover, it is found that Size-Strain plot is the most appropriate technique to estimate the crystallite sizes and lattice strain effect. However, the analysis of electrical conductivity using several model of hopping process reflected the presence of significant charges mobility and a strong electron-phonon interaction. A quantitative investigation by the frequency exponents n(T) reveals that the conduction was overpowered by the Correlated Barrier Hopping (CBH) model while the scaling exponent (a) prove the validity of time-temperature superposition principle. The frequency dependence of the dielectric constant (ε'') was attributed to the chemical micro-heterogeneity explained by the interfacial polarization type given by Koop’s theory. Furthermore, the colossal behavior of dielectric constant (ε'') with a value over 10⁶ and the presence of high electrical conductivities of 0.043 S.cm^-1 denote a possibility application of this compound in the energy storage devices.