Study of morphology and control of electric structure for carbon based hetero-nanotubes synthesized under high magnetic field
| Project/Area Number |
12640318
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
固体物性Ⅰ(光物性・半導体・誘電体)
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| Research Institution | Toyama Prefectural University |
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Principal Investigator |
YOKOMICHI Haruo Toyama Prefectural University, Associate Professor, 工学部, 助教授 (30212301)
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| Co-Investigator(Kenkyū-buntansha) |
KISHIMOTO Naoki National Research Institute for Metals, High Resolution Beam Research Station, Hybrid Beam Research Unit Leader, 精密励起場ステーション, 複号励起場ユニットリーダー (40354360)
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| Project Period (FY) |
2000 – 2001
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| Project Status |
Completed (Fiscal Year 2001)
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| Budget Amount *help |
¥3,800,000 (Direct Cost: ¥3,800,000)
Fiscal Year 2001: ¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 2000: ¥2,300,000 (Direct Cost: ¥2,300,000)
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| Keywords | high magnetic field / carbon nanotube / thermal CVD / magnetic effects / Curie temperature / scanning electron microscopy / transmission electron microscopy / カーボンナノワイヤー / 熱CVD法 / 磁場中合成 / 触媒金属 / 多層カーボンナノチューブ / 単層カーボンナノチューブ / アーク放電法 / ホットワイヤーCVD法 |
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| Research Abstract |
Carbon nanotubes were synthesized by thermal CVD under high magnetic fields of 0T,1T,5T and 10T on the SiO_2 and Si substrates using a magnetic-field-proof furnace. The C_2H_2 gas pressure and temperature were 800℃ and 30 Torr, respectively. Although subtle differences between 0T and the presence of magnetic field were discernible in the SEM images, it was difficult by SEM to precisely evaluate changes of tube length and production yield under magnetic field. The growth directions of the nanotubes and nanowires were randomly oriented in all the cases. Differences in the presence of magnetic field were scarcely discernible by SEM for the deposits under low gas pressure (10 Torr) and low temperature (10 Torr and 700℃) using Ni Although an increase of onion-like structures was discernible in TEM images for the deposits under the magnetic field, obvious magnetic effects were not observed. Accordingly, synthesis was carried out under 700℃ and 10 Torr using the Fe catalyst. The production yield of the deposits under the magnetic field decreased in the case of Fe as the catalyst, whereas the Ni catalyst did not cause such a magnetic effect. A difference between Ni and Fe is Curie temperature, which is 358℃ for Ni and 769℃ for Fe. Since the synthesis temperature was 700℃, ferromagnetism of the Fe catalyst should be maintained at the synthesis temperature. It was suggested that the magnetic field influences on formation processes of nanotubes via magnetic effects on metal catalysts. For instance, a radical pair mechanism, is possible : a singlet-triplet(S-T) spin transition for precursors generated by thermal decomposition may occur under high magnetic field. This mechanism results in the magnetic effects due to the anisotropies in g-values and hyperfine interaction constants of radicals.
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Report
(3 results)
Research Products
(10 results)
