Electric, thermoelectric and magnetic characterization of γ-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, γ-Fe₂O₃ and Co₃O₄ nanoparticles were successfully prepared by a facile thermal decomposition route, employing [Fe(C₃₂H₂₂N₄O₂)]·2H₂O and [Co(C₁₆H₁₁N₃O₄)].12">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 Co₃O₄nanoparticles with average size of ∼ 9 and 30 nm, 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 ∼1.21 eV 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.