Synthesis, Microwave Electromagnetic, and Microwave Absorption Properties of Twin Carbon Nanocoils

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• 作者：Nujiang Tang ; Wei Zhong ; Chaktong Au ; Yi Yang ; Mangui Han ; Kuanjiuh Lin ; Youwei Du
• 刊名：Journal of Physical Chemistry C
• 出版年：2008
• 出版时间：December 11, 2008
• 年：2008
• 卷：112
• 期：49
• 页码：19316-19323
• 全文大小：592K
• 年卷期：v.112,no.49(December 11, 2008)
• ISSN：1932-7455

文摘

Twin carbon nanocoils (T-CNCs) were synthesized by means of acetylene decomposition over nickel nanoparticles. From the TEM image, one can see the growth of carbon nanocoils from the opposite sides of a nickel nanodisc, making an interangle of 180°. We examined the microwave electromagnetic (EM) and microwave-absorbing properties of the as-prepared and annealed (1400 °C in Ar) T-CNCs systematically. A composite containing the as-prepared T-CNCs (15 wt %) and paraffin exhibited strong microwave absorption in a frequency range of 2 to 18 GHz. Over an absorber of double-layered composite (2.5 and 3.5 mm thickness), an absorption bandwidth of ca. 10 GHz corresponding to reflection loss below −10 dB can be obtained. We found that the magnetic parameters of the composite are low and suggest that the good absorption properties of T-CNCs should be attributed to dielectric rather than magnetic loss. It was observed that the as-prepared T-CNCs are superior to the annealed T-CNCs in microwave absorption ability, and such a phenomenon is interpreted in terms of the defect and graphitic nature of the materials. We also demonstrated that the complex permittivity and electric conductivity of T-CNCs can be controlled via annealling of T-CNCs at high temperature.