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18 results on '"Fujiwara, Ryuji"'

2. C_<70> Molecular Stumbling inside Single-Walled Carbon Nanotubes

Author

Maniwa, Yutaka, Kataura, Hiromichi, Abe, Masatoshi, Fujiwara, Akihiko, Fujiwara, Ryuji, Kira, Hiroshi, Tou, Hideki, Suzuki, Shinzo, Achiba, Yohji, Nishibori, Eiji, Takata, Masaki, Sakata, Makoto, and Suematsu, Hiroyoshi

Subjects
peapod, phase transition, XRD, fullerene, SWNT, structure, carbon nanotube, %22">C_<70>, thermal expansion
Abstract

We report the structural study of C_-one-dimensional (1D) crystal formed inside single-walled carbon nanotubes (SWNTs). X-ray diffraction measurements were performed between 100 K and 999 K on C_-encapsulated SWNTs with an average diameter of 1.37 nm. Two different domains, where the dominant alignment of C_ molecular long axis is standing or lying with respect to the tube axis, were observed; the ratio of the standing to the lying C_-domains is roughly 7:3. Thermal expansion of interfullerene distance gave no evidence for orientational phase transitions, not as in the 3D crystals. Instead, the long-range order of the standing C_-alignment was thermally destroyed with an activation energy of 39±4 meV. The results imply the importance of either the 1D fluctuation or the tube-C_ interaction at finite temperatures.

Published
2003

3. Development of On-line Analysis of Manganese in Molten Steel by EMF (Electromotive Force) Method

Author

Toshiya Harada, Kimitoshi Yonezawa, Tabuchi Satoshi, Fujiwara Ryuji, Toshihiro Ogura, and Hisashi Takamoto

Subjects
Materials science, Electromotive force, chemistry, Metallurgy, Materials Chemistry, Metals and Alloys, Molten steel, chemistry.chemical_element, Manganese, Physical and Theoretical Chemistry, Condensed Matter Physics, Line (electrical engineering)
Published
1992
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7. Multiwalled carbon nanotubes grown in hydrogen atmosphere : An x-ray diffraction study

Author

Maniwa, Yutaka, Fujiwara, Ryuji, Kira, Hiroshi, Tou, Hideki, Nishibori, Eiji, Takata, Masaki, Sakata, Makoto, Fujiwara, Akihiko, Zhao, Xinluo, Iijima, Sumio, Ando, Yoshinori, Maniwa, Yutaka, Fujiwara, Ryuji, Kira, Hiroshi, Tou, Hideki, Nishibori, Eiji, Takata, Masaki, Sakata, Makoto, Fujiwara, Akihiko, Zhao, Xinluo, Iijima, Sumio, and Ando, Yoshinori

Abstract

type:text, X-ray diffraction study of multiwalled carbon nanotube (MWNT) grown by arc discharge in hydrogen atmosphere is presented. It is found that the thermal-expansion coefficient along the radial direction of MWNT is widely distributed in a range from 1.6×10-5 K-1 to 2.6×10-5 K-1, indicating the existence of both of Russian doll MWNT and highly defective MWNT. Russian doll MWNT is suggested to have the outer diameter less than ∼100 Å . Thicker MWNT's are typically highly defective, and may have the jelly roll (scroll) or defective polygonal structure consisting of flat graphite domains.

Published
2001

8. Thermal expansion of single-walled carbon nanotube (SWNT) bundles: X-ray diffraction studies

Author

Maniwa, Yutaka, Fujiwara, Ryuji, Kira, Hiroshi, Tou, Hideki, Kataura, Hiromichi, Suzuki, Shinzo, Achiba, Yohji, Nishibori, Eiji, Takata, Masaki, Sakata, Makoto, Fujiwara, Akihiko, Suematsu, Hiroyoshi, Maniwa, Yutaka, Fujiwara, Ryuji, Kira, Hiroshi, Tou, Hideki, Kataura, Hiromichi, Suzuki, Shinzo, Achiba, Yohji, Nishibori, Eiji, Takata, Masaki, Sakata, Makoto, Fujiwara, Akihiko, and Suematsu, Hiroyoshi

Abstract

type:text, Thermal expansion coefficient in single-walled carbon nanotube bundles was determined as (-0.15±0.20)×10-5 (1/K) for the tube diameter and (0.75±0.25)×10-5 (1/K) for the triangular lattice constant by means of x-ray scattering between 300 K to 950 K. The value for the intertube gap was (4.2±1.4)×10-5 (1/K), which is larger than 2.6×10-5 (1/K) for the c-axis thermal expansion in graphite. The results reveal the presence of a remarkably larger lattice anharmonicity in nanotube bundles than that of graphite. The small value for the tube diameter is consistent with the seamless tube structure formed by a strong covalent bond between carbon atoms comparable to that in graphite.

Published
2001

9. C70Molecular Stumbling inside Single-Walled Carbon Nanotubes

Author

Maniwa, Yutaka, primary, Kataura, Hiromichi, additional, Abe, Masatoshi, additional, Fujiwara, Akihiko, additional, Fujiwara, Ryuji, additional, Kira, Hiroshi, additional, Tou, Hideki, additional, Suzuki, Shinzo, additional, Achiba, Yohji, additional, Nishibori, Eiji, additional, Takata, Masaki, additional, Sakata, Makoto, additional, and Suematsu, Hiroyoshi, additional

Published
2003
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14. A new sensor rapid analysis of silicon in hot metal electromotive force method

Author

Kuniyoshi Urata, Masao Matsuoka, Mitsuharu Tominaga, Ogura Toshihiro, and Fujiwara Ryuji

Subjects
Blast furnace, Materials science, Electromotive force, Silicon, Metallurgy, General Engineering, chemistry.chemical_element, Dynamic control, Metal, chemistry, visual_art, Thermal, Electrode, visual_art.visual_art_medium
Abstract

A probe for accurate and rapid determination of Si contents in hot metal has been developed by thermal electromotive force (EMF) measurement. The sensor has a pair of electrodes for measuring thermal EMF, which are housed in a large steel chamber to cool hot metal sample. Measurements are completed in about 1min after immersion of a few seconds.Laboratory study has been made on the applicability of the sensor to blast furnace hot metal. The adverse effects of hot metal temperature on measurement have been eliminated. It has been confirmed that there is little effect of C and Mn on measurement.

Published
1987
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15. Thermal expansion of single-walled carbon nanotube (SWNT) bundles: X-ray diffraction studies

Author

Maniwa, Yutaka, Fujiwara, Ryuji, Kira, Hiroshi, Tou, Hideki, Kataura, Hiromichi, Suzuki, Shinzo, Achiba, Yohji, Nishibori, Eiji, Takata, Masaki, Sakata, Makoto, Fujiwara, Akihiko, Suematsu, Hiroyoshi, Maniwa, Yutaka, Fujiwara, Ryuji, Kira, Hiroshi, Tou, Hideki, Kataura, Hiromichi, Suzuki, Shinzo, Achiba, Yohji, Nishibori, Eiji, Takata, Masaki, Sakata, Makoto, Fujiwara, Akihiko, and Suematsu, Hiroyoshi

Abstract

Thermal expansion coefficient in single-walled carbon nanotube bundles was determined as (-0.15±0.20)×10-5 (1/K) for the tube diameter and (0.75±0.25)×10-5 (1/K) for the triangular lattice constant by means of x-ray scattering between 300 K to 950 K. The value for the intertube gap was (4.2±1.4)×10-5 (1/K), which is larger than 2.6×10-5 (1/K) for the c-axis thermal expansion in graphite. The results reveal the presence of a remarkably larger lattice anharmonicity in nanotube bundles than that of graphite. The small value for the tube diameter is consistent with the seamless tube structure formed by a strong covalent bond between carbon atoms comparable to that in graphite.

16. Multiwalled carbon nanotubes grown in hydrogen atmosphere : An x-ray diffraction study

Author

Maniwa, Yutaka, Fujiwara, Ryuji, Kira, Hiroshi, Tou, Hideki, Nishibori, Eiji, Takata, Masaki, Sakata, Makoto, Fujiwara, Akihiko, Zhao, Xinluo, Iijima, Sumio, Ando, Yoshinori, Maniwa, Yutaka, Fujiwara, Ryuji, Kira, Hiroshi, Tou, Hideki, Nishibori, Eiji, Takata, Masaki, Sakata, Makoto, Fujiwara, Akihiko, Zhao, Xinluo, Iijima, Sumio, and Ando, Yoshinori

Abstract

X-ray diffraction study of multiwalled carbon nanotube (MWNT) grown by arc discharge in hydrogen atmosphere is presented. It is found that the thermal-expansion coefficient along the radial direction of MWNT is widely distributed in a range from 1.6×10-5 K-1 to 2.6×10-5 K-1, indicating the existence of both of Russian doll MWNT and highly defective MWNT. Russian doll MWNT is suggested to have the outer diameter less than ∼100 Å . Thicker MWNT's are typically highly defective, and may have the jelly roll (scroll) or defective polygonal structure consisting of flat graphite domains.

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