HR: 10:20h
AN: MR12A-01 INVITED    [Abstracts]
TI: First Principles Studies Of Hydrous Minerals Under High Pressure
AU: * Tsuchiya, J
EM: junt@sci.ehime-u.ac.jp
AF: Geodynamics Research Center, Ehime University, 2-5 Bunkyo-cho, Matsuyama, Ehime, 790-8577, Japan
AU: Tsuchiya, T
EM: takut@sci.ehime-u.ac.jp
AF: Geodynamics Research Center, Ehime University, 2-5 Bunkyo-cho, Matsuyama, Ehime, 790-8577, Japan
AB: Hydrogen atom is the lightest and the most abundant element in the universe. Existence of hydrogen in the deep earth is paid attention because it is known to affect the physical properties of the earth constituent minerals. Experimental techniques for determining the hydrogen positions under high pressure are still developing and the effects of hydrogen on physical properties have not been quantitatively clarified. We have investigated by first principles, the effects of hydrogen on the structural, vibrational and elastic properties of hydrous and nominally anhydrous minerals (AlOOH, MgSi₂O₆H₂, hydrous wadsleyite etc.) under high pressure condition and found that the strength of the hydrogen bond depends significantly on pressure as well as the local geometry of the hydrogen bonds. The nature of hydrogen bonds correlates with compressional, elastic and optical properties of minerals. Especially, the hydrogen bonds in δ-AlOOH and phase D, which are thought to be carriers of water into deep mantle, are predicted to have symmetric forms at lower mantle pressures. Our findings are consistent with recent high-pressure experimental results, suggesting that the density functional first principles techniques can be efficient tools for investigating the hydrous systems under high pressure. Research supported in part by JSPS.
DE: 1042 Mineral and crystal chemistry (3620)
DE: 3909 Elasticity and anelasticity
DE: 3924 High-pressure behavior
DE: 3934 Optical, infrared, and Raman spectroscopy
DE: 3954 X-ray, neutron, and electron spectroscopy and diffraction
SC: Mineral and Rock Physics [MR]
MN: 2007 Fall Meeting