第160回ジオダイナミクスセミナー
Geodynamics Seminar
"First principles study of hydrous wadsleyite under high pressure"
講師：土屋 旬（GRC学術創成研究員）
主催 ： 愛媛大学地球深部ダイナミクス研究センター
日時 ： ２００６年７月２１日（金）17：00〜
場所 ： 愛媛大学理学部講義棟１０１室
要 旨
Wadsleyite is thought to be a primary mineral phase in the Earth's
transition zone between 410 and 525 km depth. It has been pointed out
that this phase can be a significant water reservoir in the Earth. To
clarify the physical property of hydrous wadsleyite, I have determined
stable position of hydrogen in the crystal structure of wadsleyite using
the first principles computation methods. Some stable structures with
different hydrogen positions have been found and they show a
surprisingly good agreement with experimental lattice properties of
hydrous wadsleyite. As I previously reported in other hydrous minerals
stable at high pressures (d-AlOOH, phase D etc.), the hydrogen bond
plays important roles on the structural stability and the compression
mechanism of wadsleyite. Using the structural models I found,
high-pressure vibrational property and elasticity of hydrous wadsleyite
have also been simulated. Results of first principles lattice dynamics
calculations demonstrate distinct correlations between the strength of
hydrogen bond and the vibrational property. Based on these results, I
will discuss effects of water on the mantle transition zone.
問い合わせ先：土屋 卓久 TEL （089）927-8198
E-mail takut@sci.ehime-u.ac.jp
