2000 Fiscal Year Final Research Report Summary
Measurements of Elastic moduli and Equation of State on High Density Minerals by means of Resonant Sphere Technique
| Project/Area Number |
10640465
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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 |
Petrology/Mineralogy/Science of ore deposit
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| Research Institution | OKAYAMA UNIVERSITY |
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Principal Investigator |
SUZUKI Isao Okayama Univ., Earth Sci., Prof., 理学部, 教授 (60033198)
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| Co-Investigator(Kenkyū-buntansha) |
OHNO Ichiro Ehime Univ., Earth Sci., Prof., 理学部, 教授 (00116914)
ODA Hitoshi Okayama Univ., Earth Sci., Prof., 理学部, 教授 (50127552)
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| Project Period (FY) |
1998 – 2000
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| Keywords | Resonance method / elastic modulus / temperature dependence / beta phase / gamma phase / spinel / YAG / modified Wachtman equation |
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| Research Abstract |
Improvements in the temperature control system and buffer rod materials have brought increase of accuracy in spectral measurement with the resonance method. Also, theoretical analyses of three-layered oscillatory system were made and those results were applied to high pressure measurements to find pressure derivatives of elastic moduli of an isotropic material.
Beta and gamma phases were converted from San Carlos olivine at high pressures. The small specimens were shaped into spheres and used for spectrum measurements. Elasticity data up to 700 K were used to estimate elastic velocities at high pressures and temperatures. The volume ratio of olivine content around the transition layer is estimated to be 30 to 50 percents.
Accurate spectral measurements were made for a spinel MgAl_2O_4 sphere. One of the shear moduli, C_S (=(C_<11>-C_<12>)/2), shows peculiar temperature dependence. This phenomenon is explained with the order/disorder transitions of cations in spinel. Activation energy of the reaction is estimated to be E_a=300 kJ/mol. Peculiar variation is also found in internal friction Q_<44>^<-1> above 900 K.This phenomenon may arises from energy dissipation associated with the reaction.
Temperature dependence of bulk modulus K_S at ambient pressure may represented by an eqtuation K_S=K_<S0>-g E, or more generally, M=M_0-g E for elastic stiffness M.Using these equations, modified Wachtman equations, we could obtain the Debye termperature θ with almost same magnitudes for each modulus K_S, C_<11>, C_<12>, C_<44> or μ. These equations are also applicable to the elasticity data of olivine.
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