-
Tomokazu Fukutsuka, Yoshiaki Matsuo, Yosohiro Sugie, Takeshi Abe, Zemp ...
2007 Volume 2007 Issue 230 Pages
293-298
Published: November 15, 2007
Released on J-STAGE: June 28, 2010
JOURNAL
FREE ACCESS
Carbonaceous thin films were prepared by plasma-assisted chemical vapor deposition from acetylene, argon and nitrogen trifluoride (NF
3). Resulting carbonaceous thin films were characterized by scanning electron microscope (SEM), Raman spectroscopy, and Auger electron spectroscopy (AES). SEM observation and Raman spectra revealed that surface morphology and crystallinity of carbonaceous thin films depended on the flow rate of NF
3 to a great extent. Carbonaceous thin films composed of fine particles were obtained at high flow rate of NF
3. It was considered that active fluorine atoms derived from NF
3 accelerated the carbon growth at vapor phase and influenced the surface morphology and crystallinity. Based on the result of AES measurement, fluorine atoms were not contained in resulting thin films. It is concluded that addition of NF
3 to plasma is good method for control the surface morphology and crystallinity of carbonaceous thin films without contamination by fluorine atoms.
View full abstract
-
Yoshimi Ohzawa, Kohdai Mizuno, Tsuyoshi Nakajima
2007 Volume 2007 Issue 230 Pages
299-303
Published: November 15, 2007
Released on J-STAGE: June 28, 2010
JOURNAL
FREE ACCESS
Using pressure-pulsed chemical vapor infiltration technique, pyrolytic carbon (pyrocarbon) was deposited at low temperature below 1100°C from the source gases of C
6H
6 (6%)-H
2 into Ni-foam as catalyst. Pyrocarbon could be deposited at 650 °C or higher. The crystallinity was increased with the temperature elevation up to 900°C. It was found by XRD and Raman spectroscopy that high crystalline pyrocarbon particles having mainly graphite phase were deposited at 800-900°C. However, low crystalline carbon was co-deposited under the condition of temperature above 900 °C. For the samples obtained at 900°C or lower, the charge-discharge behaviors were similar to that of high crystalline natural graphite. On the other hand, “sloping region” in charge-discharge curves were observed for the sample obtained at 1000 and 1100 °C, resulting from the co-deposition of low crystalline carbon. The sample obtained at 850 t showed the highest reversible capacity of 352 mAhg
-1 at a current density of 30 mAg
-1, and 8 % of the capacity was maintained even at 3000 mAg
-1.
View full abstract
-
Kazuyuki Sudoh, Kenji Hirakuri
2007 Volume 2007 Issue 230 Pages
304-309
Published: November 15, 2007
Released on J-STAGE: June 28, 2010
JOURNAL
FREE ACCESS
Diamond growth by chemical vapor deposition technique using the iron substrates that have a high purity but different crystallite size were studied. The carbon diffusion into their substrates under the diamond growth has been measured.
The crystallite sizes of the iron materials were characterized by X-ray diffraction analysis. In addition, cross-sectional areas of the iron substrate before the diamond growth were observed by scanning electron microscope. The crystal structures and crystalite sizes of iron substrates influenced the crystalline quality of the growth diamonds. Moreover, the carbon diffusion density into the iron substrates in initial stage of diamond growth was estimated by an electron probe microanalyzer (EPMA). In the EPMA analysis, the area of 600μm in the depth and the width of 400μm were observed. In the case of the substrate with large crystallite size, the depth of high carbon concentration area (more than 1 %) was 70μm. On the other hands, the depth was 130μm in the case of the substrate with small crystallite size. It was found that the carbon diffusion density strongly depended upon the crystallite size of the base iron substrates before the growth.
View full abstract
-
Shinji Aoki, Toshiki Tsubota, Teruhisa Ohno, Tetsuro Manabe, Hirofumi ...
2007 Volume 2007 Issue 230 Pages
310-315
Published: November 15, 2007
Released on J-STAGE: June 28, 2010
JOURNAL
FREE ACCESS
Single-walled carbon nanotubes (SWNT), which is one of the most interesting materials, should be synthesized in large numbers at a low cost. We attempted to synthesize SWNT at CVD process by use of CH
4 gas, which generates at sewage treatment plant, as carbon source and zeolite as supported material. When Fe/Co bimetal was used as the catalyst, the Raman spectrum of the sample which was produced at 750°C indicated that the sample was high quality SWNT. The yield of the SWNT generation in the previous work using alcohol as the source gas. However, if the yield is improved, the method in this study is going to be interesting process.
View full abstract
-
Akira Yoshida, Yutaka Kaburagi, Yoshihiro Hishiyama
2007 Volume 2007 Issue 230 Pages
316-323
Published: November 15, 2007
Released on J-STAGE: June 28, 2010
JOURNAL
FREE ACCESS
The first order Raman spectra for benzene-derived vapor-grown carbon fibers prepared with a seeding catalyst method and heat-treated at temperatures between 1800 and 3000°C with a step of 200°C for 30 min. were studied as a function of interlayer spacing
d002. The
d002 values were obtained as values between 0.3359 and 0.3428 nm. The first order Raman spectrum was measured by a Raman spectrometer equipped with a microscope system. The full width at half maximum intensity of the G band (G-FWHM) and the intensity of the D band relative to the G band (ID/IG) can be related well to
d002 for the samples consisting of crystallites having a graphite structure. The values of G-FWHM for VGCF samples can be superimposed as a good fit to the previously obtained plots of G-FWHM against
d002 for plane-oriented Kapton carbons having
d002 values between 0.3356 and 0.3421 nm, except for plots of VGCFs with different average diameters heat-treated at 2600°C. The plots for the 2600°C-treated VGCFs could be associated with the polygonization observed for VGCFs heat-treated at temperatures above 2600°C with a scanning electron microscope. Other spectroscopic parameters, Raman frequencies for the D, D' and G bands, FWHMs for the D and D' bands and the relative intensity of the D' band to the G band ID/IG are discussed with relation to
d002.
View full abstract
-
Toshiki Tsubota, Shinji Aoki, Teruhisa Ohno, Tomoko Suenaga, Koichi Ku ...
2007 Volume 2007 Issue 230 Pages
324-328
Published: November 15, 2007
Released on J-STAGE: June 28, 2010
JOURNAL
FREE ACCESS
Carbon/limonite composite was synthesized through chemical vapor deposition of CH
4 with a help of catalysis of limonite. The limonite was heat-treated at 600°C 5 h in air before the chemical vapor deposition in order to remove impurities. When synthesis temperature was over 889°C, carbon was deposited on the limonite. Moreover, when synthesis temperature was over 1025°C, soot deposition was observed on the inner wall of reaction tube. The amount of the deposits increased with increasing synthesis temperature and time. The obtained composite was attracted by magnet.
View full abstract
-
Tetsuya Isshiki, Yuki Ota, Masanori Tomita, Takashi Yanagisawa, Yoshiy ...
2007 Volume 2007 Issue 230 Pages
329-333
Published: November 15, 2007
Released on J-STAGE: June 28, 2010
JOURNAL
FREE ACCESS
Sheet-type heaters were prepared using polyimide as a matrix with a mixture of two types of vapor-grown nanocarbon fillers, VGCF and cup-stacked carbon nanotubes (CSNT), and their electrical resistivity, thermal expansion and filler dispersion properties were evaluated. By using the heat resistant polymer, polyimide, it was expected that the positive temperature coefficient (PTC) effects appear at higher temperatures. The results showed that the nanocarbons were dispersed homogeneously and that the temperature dependence of the electrical resistivity could be controlled by the addition of two types of nanocarbon fillers. The optimum PTC properties were observed for the samples with the mixture of VGCF and CSNT at 30 wt % of total nanocarbons.
View full abstract
-
Shinya Kuroda, Yusuke Nakagawa, Masayuki Kawaguchi
2007 Volume 2007 Issue 230 Pages
334-337
Published: November 15, 2007
Released on J-STAGE: June 28, 2010
JOURNAL
FREE ACCESS
Thin films of graphite-like layered materials containing boron, carbon and nitrogen (B/C/N materials) were prepared on substrates of Ni (111) single crystal and highly oriented pyrolytic graphite (HOPG) by low pressure CVD method using acrylonitrile and boron trichloride as starting materials. Electron spectroscopy for chemical analysis (ESCA) and reflective high energy electron diffraction (RHEED) suggest that highly oriented and crystalline thin film of B/C/N material deposited on Ni (111) substrate having catalytic ability, while small amount of B/C/N film deposited on a part of HOPG substrate. Transmission electron microscopy (TEM) indicates the B/C/N thin film had a layered structure whose
ab-axis was parallel to the Ni (111) surface. These results of ESCA, RHEED and TEM strongly suggest that the B/C/N film deposited on Ni (111) substrate in a manner of hetero-epitaxial growth.
View full abstract
-
Xiuqin Chen, Seiji Motojjima
2007 Volume 2007 Issue 230 Pages
338-344
Published: November 15, 2007
Released on J-STAGE: June 28, 2010
JOURNAL
FREE ACCESS
Carbon micro-coils (CMCs) with 3D-helical/spiral structures and coil diameters of orders were obtained by the metalcatalyzed pyrolysis of acetylene at 700-800°C. In this review, the preparation process, morphology, microstructure, properties, and some applications of CMCs are introduced and their future prospect is discussed. The as-grown CMCs have almost amorphous structure, but were graphitized by high temperature heat treatment with full preservation of the coiling morphology. The CMCs could effectively generate inductive electromotive force, inductive current and thus Joul's heat under the application of microwaves. The CMCs/elastic polymer composite elements showed high tactile/proximity sensing properties which are comparable to that of human skin. The CMCs are a possible candidate for electromagnetic wave absorbers, remote heating materials, visualization elements of microwaves, tactile/proximity sensor elements, micro-antenna, chiral catalysts, bio-activators or bio-deactivators, energy converters, etc.
View full abstract
-
Hirotomo Nishihara, Hironori Orikasa, Takashi Kyotani
2007 Volume 2007 Issue 230 Pages
345-351
Published: November 15, 2007
Released on J-STAGE: June 28, 2010
JOURNAL
FREE ACCESS
It has been recognized that it is difficult to achieve uniform carbon depostion into nanospace such as micropores and mesopores by using CVD. However, we have recently demonstrated that, even in molecular-scale and labyrinthine pores like the nanochannels of zeolites, uniform carbon deposition is possible if CVD conditions are carefully selected and optimized. This review article introduces several examples of the carbon deposition into micro- and mesopores and shows key factors that impact the uniform deposition into such nanospace.
View full abstract
-
Tomokazu Fukutsuka, Yoshiaki Matsuo, Yosohiro Sugie, Takeshi Abe, Zemp ...
2007 Volume 2007 Issue 230 Pages
352-361
Published: November 15, 2007
Released on J-STAGE: June 28, 2010
JOURNAL
FREE ACCESS
Preparation of a carbonaceous thin film by plasma-assisted chemical vapor deposition was summarized. First, the resulting carbonaceous thin films were characterized. The resulting carbonaceous thin films were composed of sp
2-type carbon and the interlayer spacing (
d002) evaluated from X-ray diffraction patterns and the full width at half maximum of the G band in the Raman spectra ascribed the structure of the resulting carbonaceous thin film to a turbostratic structure. The crystallite orientation was depended on the applied rf power based on the transmission electron microscope images. Next, the resulting carbonaceous thin film was used as a negative electrode of lithium-ion batteries. Based on the various electrochemical measurements, it was found that the resulting carbonaceous thin film can be used as a model electrode. The lithium-ion insertion/extraction model was discussed. Finally, the carbonaceous thin film was applied to a coating-layer of metal as a bipolar plate material for polymer electrolyte fuel cells. The improvement in the corrosion property (suppression of metal dissolution) of carbon steel by the carbon-coating was provided by the electroless Ni plating on the carbon steel prior to the carbon-coating.
View full abstract
-
Yoshimi Ohzawa, Tsuyoshi Nakajima
2007 Volume 2007 Issue 230 Pages
362-368
Published: November 15, 2007
Released on J-STAGE: June 28, 2010
JOURNAL
FREE ACCESS
Recently, surface-modification by coating with pyrolytic carbon (pyrocarbon) using chemical vapor deposition (CVD) has been applied to graphite-based anodes of lithium-ion secondary battery (LIB) to restrain the decomposition of propylene carbonate based solvent. For non-graphitizing carbon coated with thin pyrocarbon film using chemical vapor infiltration (CVI), the irreversible capacity was significantly reduced without the decrease of reversible capacity, reflecting the laminar texture, high crystallinity and low surface area of pyrocarbon. Thus, pyrocarbon-coating by CVD/CVI technique is effective in improving the electrochemical properties of anode carbons. In present paper, recent works were summarized on synthesis and modification of anode carbons for LIB using CVD, especially CVI technique.
View full abstract
-
Hisayuki Hamajima
2007 Volume 2007 Issue 230 Pages
369-372
Published: November 15, 2007
Released on J-STAGE: June 28, 2010
JOURNAL
FREE ACCESS
-
vapor phase and solid phase reactions
Noboru Akuzawa, Rika Matsumoto
2007 Volume 2007 Issue 230 Pages
373-378
Published: November 15, 2007
Released on J-STAGE: June 28, 2010
JOURNAL
FREE ACCESS