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.
机构:
Department of Chemical Engineering, Minnesota Supercomputing Institute, University of Minnesota, Minneapolis, MN 55455, United States
Sc. Intl. Super. di Studi Avanzati, INFM-DEMOCRITOS Natl. Simulat. Ctr., 1-34014 Trieste, ItalyDepartment of Chemical Engineering, Minnesota Supercomputing Institute, University of Minnesota, Minneapolis, MN 55455, United States
Wentzcovitch, R.M.
Karki, B.B.
论文数: 0引用数: 0
h-index: 0
机构:
Department of Computer Science, Louisiana State University, Baton Rouge, LA 70803, United StatesDepartment of Chemical Engineering, Minnesota Supercomputing Institute, University of Minnesota, Minneapolis, MN 55455, United States
Karki, B.B.
Cococcioni, M.
论文数: 0引用数: 0
h-index: 0
机构:
Sc. Intl. Super. di Studi Avanzati, INFM-DEMOCRITOS Natl. Simulat. Ctr., 1-34014 Trieste, ItalyDepartment of Chemical Engineering, Minnesota Supercomputing Institute, University of Minnesota, Minneapolis, MN 55455, United States
Cococcioni, M.
De Gironcoli, S.
论文数: 0引用数: 0
h-index: 0
机构:
Sc. Intl. Super. di Studi Avanzati, INFM-DEMOCRITOS Natl. Simulat. Ctr., 1-34014 Trieste, ItalyDepartment of Chemical Engineering, Minnesota Supercomputing Institute, University of Minnesota, Minneapolis, MN 55455, United States