Electrical conductivity and dielectric behaviour of nanocrystalline La _0.6Gd _0.1Sr _0.3Mn _0.75Si _0.25O ₃

Abstract

An La _0.6Gd _0.1Sr _0.3Mn _0.75Si _0.25O ₃ ceramic was prepared via a solution-based chemical technique. X-ray diffraction study confirms the formation of the compound in the orthorhombic structure with the Pnma group space. Dielectric properties have been investigated in the temperature range of 85–290 K with the frequency range 40 Hz to 2 MHz. The conductivity spectra have been investigated by the Jonscher universal power law: σ( ω)  =   σ _dc  +   Aω ⁿ , where ω is the frequency of the ac field, and n is the exponent. The deduced exponent ‘ n’ values prove that a hopping model is the dominating mechanism in the material. Based on dc-electrical resistivity study, the conduction process is found to be dominated by a thermally activated small polaron hopping (SPH) mechanism. Complex impedance analysis (CIA) indicates the presence of a relaxation phenomenon and allows us to modelize the sample in terms of an electrical equivalent circuit. Moreover, the impedance study confirms the contribution of grain boundaries to the electrical properties.

Abstract

A complex impedance spectrum for La _0.6Gd _0.1Sr _0.3Mn _0.75Si _0.25O ₃ sample at different temperatures with electrical equivalent circuit.