Electric, thermoelectric and magnetic characterization of γ-Fe2O3 and Co3O4 nanoparticles synthesized by facile thermal decomposition of metal-Schiff base complexes

Abstract

Using novel compounds for synthesis of metal oxide nanomaterials can tune their physical properties due to the associated variation in the shape, size and crystallinity. In this work, γ-Fe2O3 and Co3O4 nanoparticles were successfully prepared by a facile thermal decomposition route, employing [Fe(C32H22N4O2)]·2H2O and [Co(C16H11N3O4)].12H2O complexes, respectively as new precursors. The x-ray diffraction and high resolution transmission electron microscopy investigation confirmed that the materials consist of highly pure spinel γ-Fe2O3 and Co3O4 nanoparticles with average size of∼9 and 30nm, respectively. The electrical conduction is governed by the hopping mechanism. The thermoelectric power measurements confirmed that Co3O4 nanoparticles are non-degenerate semiconductor with Fermi energy ∼1.21eV while γ-Fe2O3 nanoparticles showed a degenerate to non-degenerate transition. The Co3O4 nanoparticles showed a weak ferromagnetic ordering that could be attributed to uncompensated surface spins due to finite-size effects. But γ- Fe2O3 NPs show superparamagnetic behavior at room temperature.