2000 Fiscal Year Final Research Report Summary
Thermal Diffusivity Measurement of Upper Mantle Minerals at Ultra-high Pressures and Temperatures
| Project/Area Number |
09440188
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| Research Category |
Grant-in-Aid for Scientific Research (B).
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Petrology/Mineralogy/Science of ore deposit
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| Research Institution | Okayama University |
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Principal Investigator |
KATSURA Tomoo Institute for Study of the Earth's Interior, Okayama University, Associate Professor, 固体地球研究センター, 助教授 (40260666)
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| Co-Investigator(Kenkyū-buntansha) |
KANZAKI Masami Institute for Study of the Earth's Interior, Okayama University, Associate Professor, 固体地球研究センター, 助教授 (90234153)
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| Project Period (FY) |
1997 – 2000
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| Keywords | Thermal diffusivity / Angstrom method / periclase / forsterite / zircona / corundum |
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| Research Abstract |
In this study, first we constructed a measurement system of thermal diffusivity by Angstrom method We constructed a heating system using a programmable power source which can modulate electric voltage such that electric power sinusoidally changes. Using an external trigger, we measure emf of two thermocouples inserted to a sample to determine phase lag between temperature oscillations at two different points. The positions of two thermocouples are measured opetically. Thermal diffusivity is calculated from these positions and the phase lag.
We measured thermal diffusivity of periclase, forsterite, zircona and corundum at high pressures and temperatures. Thermal diffusivity of all of these materials decreases with increasing temperature and increases with increasing temperature. Reciprocal thermal diffusivity of periclase is linearly increases with increasing temperature as is the case of simple materials. Its gradient decreases with increasing pressure. Reciprocal thermal diffusivity of forsterite shows curvature as is the case of Fo89 olivine. This may be due to complex crystal structure of forsterite. Reciprocal thermal diffusivity of corundum shows a linear relation with temperature. However, its gradient does not change with increasing temperature. It is possible that measurement for corundum was failed because thermal diffusivity of corundum is very high
Thermal diffusivity of forsterite is 30% larger than that of fo89 olivine. Thermal diffusivity of forsterite increases by 40% over 6 GPa. This pressure dependence is about 40% larger than that of fo89 olivine.
Thermal diffusivity of zirconia measured at high pressure is more than 50% larger than expected from the measurement at ambient conditions.
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