Synthesis and Electrical Property of VO 2 (M) Nanorods
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Synthesis and Electrical Property of VO2 (M) Nanorods W. Chen *, L. Q. Mai, Y. Y. Qi, H. Yu, J. F. Peng Institute of Materials Science and Engineering, Wuhan University of Technology, Wuhan 430070 Hubei, P. R. China ABSTRACT VO2 (M) nanorods have been synthesized and the morphology and structure of the sample were characterized by XRD, SEM, and HRTEM. The results show that for VO2 (M) nanorods, the transition temperature is 65 and the hysteresis loop width is 8 . The active energy of low temperature semiconducting phase is 0.2eV, which indicates that its Fermi energy level situates on the middle energy level of the forbidden-band. The doping of Mo6+ decreases its transition temperature.
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INTRODUCTION Vanadium oxides have been linked to interesting physical and chemical properties which lead to a wide range of applications in temperature sensing devices, optical switching devices, energy-conserving coating for windows and so on[1, 2]. Vanadium dioxide has Mott transition properties from low-temperature semiconductor phase to high-temperature metal phase. Its phase transition temperature is approximately 68 . Recently, one-dimensional nanostructure materials, such as nanotubes, nanowires and nanorods, have attracted much attention due to their unique properties originated from their high surface area and low dimensionality [3]. It is a challenging and valuable work to study vanadium dioxide (M) nanorods. In the paper, VO2(M) are synthesized by treatingVO2(B) nanorods with H2O2 and CTAB solution. XRD, SEM, HRTEM and electrical investigation were performed to study the structure and electrical property of VO2 (M) nanords.
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EXPERIMENTAL DETAILS VO2(M) nanorods were prepared via a rheological phase reaction followed by self-assembling process as previously described [4]. 10 mmol V2O5 and 10 mmol cetyltrimethyl ammonium bromide was mixed with 5 ml distilled water. After stirring for 1 hour, 15 ml distilled water was added to the orange solution. After aging for 48 hours, the resulting rheological suspension was transferred into a Teflon-lined autoclave with a stainless steel shell. The autoclave was kept at 180 for about a week. The final black product(VO2( B)) was washed with distilled water and dried at 80 for 8 h. At last 40% H2O2 and saturated CTAB solution were dropped to the VO2(B), followed by washing and drying again. XRD experiments were done on a D/MAX-III X-ray diffractrometer with Cu Kα radiation and graphite monochrometer. SEM images were attained using a JSM-5610LV scanning electron microscope at 80 kV. TEM image was taken in a JEOL JEM-2010FEF microscope operated at 200 kV. HP-4294A apparatus and self-designed heating instrument were used to investigate the
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* The corresponding author. E-mail: [email protected]
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electrical properties of the samples. RESULTS AND DISCUSSION Powder X-ray diffraction (XRD) is consistent with monoclinic VO2 (M) phase (figure 1). The cell parameters are in good agreement with that found for bulk material(a=5.744Å, b=4.517Å, c=5.376Å, β=122.7).
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