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

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, gamma-Fe2O3 and Co3O4 nanoparticles were successfully prepared by a facile thermal decomposition route, employing [Fe(C32H22N4O2)]center dot 2H(2)O and [Co(C16H11N3O4)]center dot 1/2H(2)O 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 gamma-Fe2O3 and Co(3)O(4 )nanoparticles with average size of similar to 9 and 30 nm, respectively. The electrical conduction is governed by the hopping mechanism. The thermoelectric power measurements confirmed that Co3O4 nano-particles are non-degenerate semiconductor with Fermi energy similar to 1.21 eV while gamma-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 gamma-Fe2O3 NPs show super-paramagnetic behavior at room temperature.