Colossal permittivity, impedance analysis, and optical properties in La0.67Ba0.25Ca0.08Mn0.90Ti0.10O3 manganite

This work investigated the dielectric and optical process of La0.67Ba0.25Ca0.08Mn0.90Ti0.10O3 (LBCMT) manganite using impedance spectroscopy and ellipsometric spectroscopy. LBCMT nano-polycrystalline sample synthesized by the molten salt method was subjected to annealing it 1000 °C. The dielectric performance was estimated on the basis of the polarization of space load relating to the two-layer Maxwell–Wagner’s pattern and the load jump carriers Mn3+ / Mn4+ ions. The frequency-dependent dielectric constant showed normal behavior. The variation of the differential of ANC was found at 400 K in LBCMT. The complex impedance measurements’ inputs showed that the Nyquist plots were adjusted by an appropriate equivalent circuit, implying that both input ascribed to grains and grain boundaries are related to an inductance. Relaxation phenomena of non-Debye type were observed in our ceramic compound, as confirmed by the electrical modulus. Moreover, the frequency related to electrical data was found to obey the law of Jonscher’s. Correlated barrier hoping was determined to be the most appropriate theoretical model to explain the electrical behavior. The activation energies were proved to be < 1 eV for the conduction and relaxation mechanisms, suggesting that the processes could be mainly caused by the ionic conductivity of oxygen rather than electronic conductivity and oxygen vacancies. The optical properties: refractive index and extinction coefficient were studied at room temperature by using spectroscopic ellipsometry.