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Issue 17, 2018
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Conductivity dynamics of metallic-to-insulator transition near room temperature in normal spinel CoFe2O4 nanoparticles

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Abstract

Herein, we report the preparation of minute CoFe2O4 nanoparticles which exhibit an unusually normal spinel characteristic and a metallic behavior at room temperature that has not yet been reported in the literature for such materials. A study on the synthesis and characterization of these nanoparticles and the effect of cation distribution on electrical properties was conducted. A xerogel was treated at 300 °C for 20 hours and the as-synthesized powder was structurally and electrically characterized. X-ray diffraction studies indicate that the synthesis pathway was successful in producing crystalline nanoparticles under such mild conditions. TEM images demonstrate that CoFe2O4 consists of monodispersed nanocrystalline particle aggregates with a particle size of ∼10 nm. Mössbauer spectroscopy investigation shows a normal spinel configuration, which is highly unusual for cobalt ferrite. Impedance analyses confirm that the material has a metallic characteristic at temperatures close to room temperature which arises as a consequence of octahedral site occupancy. Above 100 °C, the material displays a metallic-to-insulator transition, which has been related to the predominant OLPT conduction mechanism. An endothermic peak in the DSC curve indicates the occurrence of a structural transition which was associated with the Verwey-type reordering of charged metallic atoms.

Graphical abstract: Conductivity dynamics of metallic-to-insulator transition near room temperature in normal spinel CoFe2O4 nanoparticles

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Publication details

The article was received on 07 Jan 2018, accepted on 28 Mar 2018 and first published on 29 Mar 2018


Article type: Paper
DOI: 10.1039/C8TC00099A
Citation: J. Mater. Chem. C, 2018,6, 4720-4726
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    Conductivity dynamics of metallic-to-insulator transition near room temperature in normal spinel CoFe2O4 nanoparticles

    J. Venturini, R. Y. S. Zampiva, D. H. Piva, R. H. Piva, J. B. M. da Cunha and C. P. Bergmann, J. Mater. Chem. C, 2018, 6, 4720
    DOI: 10.1039/C8TC00099A

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