Study of conduction phenomena in indium substituted Mn–Zn nano-ferrites

• Preparation of single phase Indium substituted Mn–Zn ferrites by oxalate coprecipitation technique.
• Study of thermal variation of dc resistivity and the change in activation energy at curie temperature. Curie temperature determined by Loria–Sinha technique.
• Study of thermal variation of thermoelectric power, n-type of charge carriers and carrier concentration.

Nanocrystalline Indium substituted Mn–Zn ferrites were prepared by oxalate coprecipitation technique in combination with microwave heating. X-ray diffraction and scanning electron microscopy was used to study nano-structural parameters such as crystallite size, lattice constant, X-ray density, observed density and morphology of the synthesized nanopowders. The lattice constant, crystallite size and X-ray density increased with increase in Indium concentration. Thermal variation of dc resistivity was studied by two probe method. The resistivity decreased exponentially with increasing Indium concentration and the change of slope of dc resistivity plot was observed at Curie temperature. Small polaron hopping between Fe2+ and Fe3+ ions at octahedral sites was established. Substitution of Indium ions increased the dc resistivity. Differential method was used to study thermoelectric power. Thermo-emf remained constant with increasing temperature; the n-type conduction mechanism and localization of charge carriers at lattice sites due to strong electron–phonon interaction was established.