Investigation of charge transport mechanism in semiconducting La0.5Ca0.5Mn0.5Fe0.5O3 manganite prepared by sol-gel method

Here in, we report the charge transport mechanism in semiconducting La0.5Ca0.5Mn0.5Fe0.5O3 (LCMFO) polycrystalline material synthesized via sol-gel auto combustion route. X-ray diffraction (XRD) analysis confirmed the orthorhombic phase of the prepared material. Temperature dependent resistivity and impedance spectroscopy measurements have been carried out to probe the dielectric and electrical conduction mechanism which revealed a change of Mott variable range to the small polaronic hopping conduction mechanism around 303 K. The complex impedance and modulus spectra undoubtedly showed the contribution of both grain and grain boundary effect on the conduction properties of LCMFO. An equivalent circuit [(R(gb)Q(gb)) (R(g)Q(g))] model has been used to address the electrical parameters associated with the different phases (grains and grain boundaries) having different relaxation times. The values of resistances of two phases obtained after fitting the equivalent circuit in the nyquist plot have been analyzed which confirmed the change of conduction mechanism around 303 K. The resultant change in conduction mechanism is also supported by the conductivity plots.