| Project/Area Number |
16540299
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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 |
Condensed matter physics I
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| Research Institution | Kumamoto University |
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Principal Investigator |
YOKOI Hiroyuki Kumamoto Univ., Fac.of Engineering, Associate Prof., 工学部, 助教授 (50358305)
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| Project Period (FY) |
2004 – 2005
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| Project Status |
Completed (Fiscal Year 2005)
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| Budget Amount *help |
¥3,300,000 (Direct Cost: ¥3,300,000)
Fiscal Year 2005: ¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 2004: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Keywords | metal silicate tube / magnetic field induced double helix / Lorentz force / magnetic force / osmotic pressure / in-situ obseerbation / chemical garden / anion flow / 磁場誘起ヘリカル構造 / 二重らせん / 浮力 / 流れの可視化 |
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| Research Abstract |
We have found a novel phenomenon that freestanding metal silicate tube growing from metal salt powders such as FeCl_2 and CoCl_2 immersed in water solution of sodium silicate forms a twisted (chiral or helical) structure. In the growing process of metal silicate tubes, aqueous solution of metal salts is delivered through the tubes and emitted at the growing ends. We have given experimental proofs on that the Lorentz force exerting on anions in the metal salt solution is related to the formation of the helical structure. However, why the Lorents force exerts on anions was unresolved because the flow of the metal salt solution is parallel to applied magnetic field. We have proposed the following model in order to explain the reason : Among ions included in the metal salt solution, metal ions are trapped in metal silicate membranes, while anions are emitted outward and could have a motion component perpendicular to the magnetic field. The Lorentz force would exert on such macroscopic flow of anions and generate vertex, which would twist the tube before the solidification. In order to confirm this model, we have developed an in-situ observation system under magnetic fields. In a gradient field of B=2.2 T and B・dB/dx=46 T^2/m, vortex flow was observed around a growing end of a cobalt silicate tube from a CoCl_2 powder in 10wt.% water solution of sodium silicate. In the experiments, we have also noticed that the growing ends often take shape of two horns. Further detailed investigation has revealed that the helical structure of the metal silicate tubes is double helix formed by twining of the two horns. It is the first time in our knowledge that the double helix like DNA is observed in the formation of inorganic membranes.
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