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The electromagnetic wave absorption properties of single- and double-layer silver nanoparticle/carbon nanotube (Ag/CNT) nanocomposites were evaluated. The reflection loss (R.L.) of the samples was calculated based on the measured complex permittivity and permeability. The double-layer composites constructed from CNT 30 wt.% and Ag/CNT 30 wt.% with total thickness of 3.3 mm showed a minimum R.L. of ∼−52.9 dB (over 99.999% absorption) at 6.3 GHz. The bandwidth of reflection loss less than −10 dB was observed at 3 regions, with wideness of 3.5, 0.8, and 1.5 GHz. Thin absorber with large R.L. and wide response bandwidth at low and high frequency regions can be obtained with double-layer composites. The capability to modulate the absorption and bandwidth of these samples to suit various applications in different frequency bands indicates that these nanocomposites could be an excellent electromagnetic wave absorber.

Helical graphite whiskers (GWs) have been synthesized from fullerene waste soot, which is a byproduct in fullerene production by arc discharge technique, at 2600 °C for 1 h with Ar gas flow at 760 Torr. The as-synthesized GWs consisting of graphite layers with some disclination possess various kinds of morphological structures with loop-like brims and arch-shaped protrusion on their surfaces, as observed by scanning and transmission electron microscopy. The GWs show strong intensity of 2D peak in Raman spectra, which could be attributed to disclination in the whiskers.

Graphene-sheet fiber, a novel structure of graphitic carbon, grew from coffee grounds under the condition of microwave plasma irradiation. The resulting fiber consisted of only few-layer graphene without a hollow structure inside while possessing a large amount of graphene edges and high conductivity. Due to these advantages, graphene-sheet fibers may find applications in electrochemical energy conversion and storage.

Article, JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS. 69(10): 2481-2486 (2008)

A simple construction of sol–gel sheaths onto the surface of multi-walled carbon nanotubes (MWCNTs) has been carried out in water by a hydrophobicity-induced covering with the assistance of ultrasound. The ultrasound assistance prevents in water an unregulated agglomeration induced by the hydrophobicity of MWCNTs and phenyl-containing sols, leading to a selective construction of sol–gel sheaths on the nanotube surface. The phenyl groups of the resulting sol–gel sheaths were successfully removed by air-oxidation to provide the MWCNTs covered with amorphous SiO 2 sheaths. The effect of the SiO 2 sheaths on the electrical and thermal properties of the SiO 2 -MWCNT nanocomposites was evaluated from the electrical resistivities of the nanocomposites with two different SiO 2 concentrations and the thermal conductivities of their phenol-resin composites. The results indicate that the small increase of the SiO 2 concentration remarkably increases the electrical resistivity of the SiO 2 -MWCNT nanocomposites. Furthermore, the SiO 2 sheaths have more directly influenced the thermal property of the polymer composites than the inside nanotubes.

Article, SCRIPTA MATERIALIA. 58(4): 267-270 (2008)

We fabricated silver–carbon nanotube (Ag–CNT) composite plating films and prepared samples after a H2S gas corrosion test. After corrosion, although the elastic modulus of Ag film increased 1.9 times, there was no marked difference in the mechanical characteristic of Ag–CNT film. At a low load, for the Ag–CNT film after corrosion, there was no polarity and the contact resistance was low and ohmic, although the contact resistance of Ag film after corrosion was high and polar. Therefore, Ag–CNT film can be considered as a promising material for next-generation electrical contact applications.

This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in APPLIED PHYSICS LETTERS. 92(6):63105 (2008) and may be found at https://doi.org/10.1063/1.2842411 ., Article, APPLIED PHYSICS LETTERS. 92(6):63105 (2008)

Free-standing diamond films are prepared by CVD technique to examine their properties directly. The products have a variety of shapes such as plates, tubes and curved diaphragms. Coefficients of thermal expansion (GTE) of the tube are similar to the values of a bulk diamond in the range from 40°C to 500°C. It is found that polished diamond film has uniform infrared transmission ranging from 500cm-1 to 4000cm-1. A speaker diaphragm will be a good application for free-standing diamond film.© (1990) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.