Electrical conductivity and dielectric behaviour of nanocrystalline La 0.6 Gd 0.1 Sr 0.3 Mn 0.75 Si 0.25 O 3 .

An La 0.6 Gd 0.1 Sr 0.3 Mn 0.75 Si 0.25 O 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.