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標題: Synthesis, Microwave Electromagnetic, and Microwave Absorption Properties of Twin Carbon Nanocoils
作者: Tang, N.J.
Zhong, W.
Au, C.T.
Yang, Y.
Han, M.G.
Lin, K.J.
Du, Y.W.
關鍵字: large-scale synthesis;absorbing properties;nanotubes;composites;microcoils;coils;nanofibers;pyrolysis;mechanism;coatings
Project: Journal of Physical Chemistry C
期刊/報告no:: Journal of Physical Chemistry C, Volume 112, Issue 49, Page(s) 19316-19323.
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 degrees. We examined the microwave electromagnetic (EM) and microwave-absorbing properties of the as-prepared and annealed (1400 degrees 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 nim 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.
ISSN: 1932-7447
DOI: 10.1021/jp808087n
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