The growing mechanism of alpha-Fe(2)O(3) nanowires synthesized by thermal oxidation of iron is studied by the Monte Carlo method. Using a model of diffusion, the effects of synthesizing temperature, oxygen density and annealing on the morphology of the nanowires have been simulated. The results show that nanowires with a large head can only be obtained under the correct temperature and a sufficiently high density of oxygen. Under a low temperature or a low density of oxygen, particles can be obtained. And under a high temperature or after annealing, the nanowires will become thicker. The results are consistent with our experiments. This fact indicates that the growth of alpha-Fe(2)O(3) nanowires should be a diffusion process and provides an approach for improving the quality of the nanowires.
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http://dx.doi.org/10.1039/b9nr00188c | DOI Listing |
Molecules
November 2024
Wuhan National Laboratory for Optoelectronics, School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, China.
Among the transition metal oxides, hematite (α-FeO) has been widely used in the preparation of memristors because of its excellent physical and chemical properties. In this paper, α-FeO nanowire arrays with a preferred orientation along the [110] direction were prepared by a facile hydrothermal method and annealing treatment on the FTO substrate, and then α-FeO nanowire array-based Au/α-FeO/FTO memristors were obtained by plating the Au electrodes on the as-prepared α-FeO nanowire arrays. The as-prepared α-FeO nanowire array-based Au/α-FeO/FTO memristors have demonstrated stable nonvolatile bipolar resistive switching behaviors with a high resistive switching ratio of about two orders of magnitude, good resistance retention (up to 10 s), and ultralow set voltage (V = +2.
View Article and Find Full Text PDFMolecules
April 2023
Institute of Advanced Optoelectronic Materials and Technology, College of Big Data and Information Engineering, Guizhou University, Guiyang 550025, China.
A facile hydrothermal process has been developed to synthesize the α-FeO nanowire arrays with a preferential growth orientation along the [110] direction. The W/α-FeO/FTO memory device with the nonvolatile resistive switching behavior has been achieved. The resistance ratio (R/R) of the W/α-FeO/FTO memory device exceeds two orders of magnitude, which can be preserved for more than 10s without obvious decline.
View Article and Find Full Text PDFNanomaterials (Basel)
July 2019
School of Resources and Civil Engineering, Northeastern University, Shenyang 110819, China.
One-dimensional Zn-doped α-FeO nanowires have been controllably synthesized by using the pure pyrite as the source of Fe element through a two-step synthesis route, including the preparation of Fe source solution by a leaching process and the thermal conversion of the precursor solution into α-FeO nanowires by the hydrothermal and calcination process. The microstructure, morphology, and surface composition of the obtained products were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. It was found that the formation process of α-FeO is significantly influenced by the introduction of Zn.
View Article and Find Full Text PDFNanomaterials (Basel)
December 2018
Bejing Key Laboratory of Quantum Devices, Key Laboratory for the Physics and Chemistry of Nanodevices, and Department of Electronics, Peking University, Beijing 100871, China.
It is difficult to obtain γ-Fe₂O₃ nanostructures by heating iron substrate in ambient conditions because γ-Fe₂O₃ is less thermodynamically stable than α-Fe₂O₃. In this work, we synthesize γ-Fe₂O₃ nanowires by heating iron particles under an external force. The stacking style of iron and oxygen ions under a strong shearing stress tends to adopt the γ-Fe₂O₃ structure regardless of the thermodynamic restriction.
View Article and Find Full Text PDFNanomaterials (Basel)
July 2018
School of Materials Science and Engineering, Shenyang University of Technology, Shenyang 110870, China.
Porous α-Fe₂O₃ nanowire arrays coated with a layer of carbon shell have been prepared by a simple hydrothermal route. The as-synthesized products show an excellent electrochemical performance with high specific capacitance and good cycling life after 9000 cycles. A solid state asymmetric supercapacitor (ASC) with a 2 V operation voltage window has been assembled by porous α-Fe₂O₃/C nanowire arrays as the anode materials, and MnO₂ nanosheets as the cathode materials, which gives rise to a maximum energy density of 30.
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