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|標題:||Synthesis, Microwave Electromagnetic, and Microwave Absorption Properties of Twin Carbon Nanocoils||作者:||Tang, N.J.
|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.||摘要:||
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.
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