| Project/Area Number |
11102004
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| Research Category |
Grant-in-Aid for Specially Promoted Research
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| Allocation Type | Single-year Grants |
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| Review Section |
Physics
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| Research Institution | KYOTO UNIVERSITY (2001-2003)
Hiroshima University (1999-2000) |
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Principal Investigator |
TAMURA Kozaburo Kyoto University, Graduate School of Engineering, Professor, 工学研究科, 教授 (30155262)
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| Co-Investigator(Kenkyū-buntansha) |
SHIMOJO Fuyuki Kumamoto University, Faculty of Science, Associate Professor, 理学部, 助教授 (60253027)
HOSHINO Kozo Hiroshima University, Faculty of Integr. Arts and Sciences, Professor, 総合科学部, 教授 (30134951)
INUI Masanori Hiroshima University, Faculty of Integr. Arts and Sciences, Associate Professor, 総合科学部, 助教授 (40213136)
UTSUMI Wataru The Japan Atomic Energy Research Institute, Researcher, 研究員
FUNAKOSHI Kenichi Japan Synchrotron Radiation Research Institute, Researcher, 研究員
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| Project Period (FY) |
1999 – 2003
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| Keywords | Supercritical fluids / Metal-nonmetal transition / Synchrotron radiation / Static and dynamic structure / Density fluctuations / Mercury / Rubidium / Selenium |
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| Research Abstract |
We have performed structural investigations on expanded fluid metals such as Hg, Rb and Se focusing on the metal-nonmetal (M-NM) transition. These substances are typical examples in which the M-NM transit ion occurs with volume expansion. Hg is a divalent metal and the M-NM transition with the Wilson type takes place. In the M-NM transition of fluid Rb the electron correlation is considered to play a key role. Se is a liquid semiconductor which shows the semiconductor-metal-insulator transition with expansion.
We have measured x-ray diffraction, small angle x-ray scattering and inelastic x-ray scattering at temperatures up to 2000 K and pressures up to 2000 bar with He gas compression, in the wide density region from liquid to dense vapor surrounding the liquid-vapor critical point, by the use of synchrotron radiation at SPring-8. We have accumulated structural data of static and dynamic ones such as S(Q), g(r) and S(Q,ω). We have obtained important results showing strong correlation between the M-NM transition and the structural change. For example, small angle x-ray scattering measurements for fluid Hg reveals that a weak density fluctuation appears accompanying the M-NM transition. From the inelastic x-ray scattering measurement for fluid Hg we have observed a fast sound at the M-NM transition region. The sound velocity is triple the ultrasonic velocity. The fast sound is strongly connected with the fluctuation in the local structure with the time-and-space scale of nm and ps which may induce the M-NM transition. In Rb and Se we have also obtained important results. For fluid Rb we have developed a molybdenum cell the use of which enabled us the structural studies up to the supercritical region.
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