Phase transition in MgSiO3 perovskite in the earth's lower mantle

被引：416

作者：

Tsuchiya, T ^{[1
]}

Tsuchiya, J ^{[1
]}

Umemoto, K ^{[1
]}

Wentzcovitch, RA ^{[1
]}

机构：

[1] Univ Minnesota, Dept Chem Engn & Mat Sci, Minnesota Supercomp Inst Digital Technol & Adv Co, Minneapolis, MN 55455 USA

来源：

EARTH AND PLANETARY SCIENCE LETTERS | 2004年 / 224卷 / 3-4期

基金：

美国国家科学基金会; 日本学术振兴会;

关键词：

post-perovskite; MgSiO3; first principle; core-mantle boundary; D '' layer;

D O I：

10.1016/j.epsl.2004.05.017

中图分类号：

P3 [地球物理学]; P59 [地球化学];

学科分类号：

0708 ; 070902 ;

摘要：

A new polymorph of MgSiO3 more stable than the Pbnm-perovskite phase has been identified by first-principles computations. It has the CaIrO3 structure with Cmcm symmetry and consists of SiO3 layers intercalated by eightfold-coordinated Mg ions. High-temperature calculations within the quasiharmonic approximation give a volume change of similar to 1.5% and a Clapeyron slope of similar to 7.5 +/- 0.3 MPa/K at similar to 2750 K and similar to 125 GPa. These pressure-temperature (P-T) conditions are close to those in which a phase transition in MgSiO3-perovskite has been observed by in situ angle dispersive X-ray diffraction measurements. This transition appears to be associated with the W discontinuity. (C) 2004 Elsevier B.V All rights reserved.

引用

页码：241 / 248

页数：8

共 33 条

[1] Equation of state of bismuth to 222 GPa and comparison of gold and platinum pressure scales to 145 GPa [J].