Origin of dc and ac electric transport phenomena in carbon/manganese oxide nanocomposite |
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| Institution: | 1. National Isotope Centre, GNS Science, PO Box 31312, Lower Hutt 5010, New Zealand;2. The MacDiarmid Institute for Advanced Materials and Nanotechnology, PO Box 600, Wellington 6140, New Zealand;1. Institut für Physik, Johannes Gutenberg-Universität Mainz, Staudinger Weg 7, 55128 Mainz, Germany;2. Graduate School of Excellence ‘Material Science in Mainz’, Staudinger Weg 9, 55128 Mainz, Germany;3. Institut für theoretische Physik, TU Bergakademie Freiberg, Leipziger Str. 23, 09596 Freiberg, Germany;1. Unité de physique des dispositifs à semi-conducteurs, Tunis EL MANAR University, 2092 Tunis, Tunisia;2. Faculté des Sciences de Bizerte, Université de Carthage, Zarzouna 7021, Tunisia;3. Physics Department, Faculty of Arts and Sciences, Marmara University, Göztepe, Istanbul 34722, Turkey;1. Key Lab for Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061, China;2. Engineering Ceramics Key Lab. of Shandong Province, Shandong University, Jinan 250061, China;1. Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC, 29208, USA;2. Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA |
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| Abstract: | Hybrid organic/inorganic nanocomposites based on manganese oxide nanoparticles enriched pyrogallol-formaldehyde matrix (PF/MnO) were synthesized by sol-gel technique. After a drying step, the samples were heated during 2 h at different pyrolysis temperatures between 600 and 1000 °C in tubular furnace under open nitrogen atmosphere. The obtained nanocomposites were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and electrical technics in the measurement temperature range between 80 and 300 K. The XRD spectra show that PF/MnO nanocomposites are crystallized with the appearance of different phases: the graphite (C), the manganese oxide (MnO), the metallic manganese (Mn) and the manganese dioxide (MnO2) with proportions depending on pyrolysis temperature. The measurement temperature dependence conductivity can be explained by Godet-Variable Range Hopping (3D-GVRH) conduction model in all samples with the presence of an exponential distribution of localized states. The voltage-current V(I) characteristics show the presence of negative differential resistance (NDR) in some samples. The ac conductance exhibits the dominance of hopping conduction mechanism and the Small Polaron Hopping (SPH) model. The Nyquist plots for the PF/MnO-650 °C nanocomposite obey at Cole-Cole model. The impedance spectra were fitted by an equivalent circuit involving two contributions attributed to grains and grain boundaries. |
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| Keywords: | Hybrid organic/inorganic nanocomposites Sol-gel Pyrolysis temperature Negative differential resistance Electrical conductivity Impedance spectroscopy |
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