Elastic properties of body-centered cubic iron in Earth's inner core

被引:21
作者
Belonoshko, Anatoly B. [1 ,2 ]
Simak, Sergei I. [3 ,4 ]
Olovsson, Weine [3 ]
Vekilova, Olga Yu. [5 ]
机构
[1] Royal Inst Technol KTH, AlbaNova Univ Ctr, Dept Phys, Condensed Matter Theory, S-10691 Stockholm, Sweden
[2] Univ S Florida, Dept Phys, Tampa, FL 33620 USA
[3] Linkoping Univ, Dept Phys Chem & Biol IFM, SE-58183 Linkoping, Sweden
[4] Uppsala Univ, Dept Phys & Astron, Box 516, SE-75120 Uppsala, Sweden
[5] Stockholm Univ, Dept Mat & Environm Chem, Stockholm, Sweden
基金
瑞典研究理事会; 欧洲研究理事会;
关键词
ENERGY CALCULATIONS; FE; STABILITY; STABILIZATION; ANISOTROPY;
D O I
10.1103/PhysRevB.105.L180102
中图分类号
T [工业技术];
学科分类号
08 ;
摘要
The solid Earth's inner core (IC) is a sphere with a radius of about 1300 km in the center of the Earth. The information about the IC comes mainly from seismic studies. The composition of the IC is obtained by matching the seismic data and properties of candidate phases subjected to high pressure (P) and temperature (T). The close match between the density of the IC and iron suggests that the main constituent of the IC is iron. However, the stable phase of iron is still a subject of debate. One such iron phase, the body-centered cubic phase (bcc), is dynamically unstable at pressures of the IC (330-364 GPa) and low T but gets stabilized at high T characteristic of the IC (5000-7000 K). So far, ab initio molecular dynamics (AIMD) studies attempted to compute the bcc elastic properties for a small (order of 102) number of atoms. The mechanism of the bcc stabilization cannot be enabled in such cells and that has led to erroneous results. Here we apply AIMD to compute elastic moduli and sound velocities of the Fe bcc phase for a 2000 Fe atom computational cell, which is a cell of unprecedented size for ab initio calculations of iron. Unlike in previous ab initio calculations, both the longitudinal and the shear sound velocities of the Fe bcc phase closely match the properties of the IC material at P = 360 GPa and T = 6600 K, likely the PT conditions in the IC. The calculated density of the bcc iron at these PT conditions is just 3% higher than the density of the IC material according to the Preliminary Earth Model. This suggests that the widely assumed amount of light elements in the IC may need a reconsideration. The anisotropy of the bcc phase is an exact match to the most recent seismic studies.
引用
收藏
页数:6
相关论文
共 49 条
[1]  
Al'tshuler L., 1958, Soviet Physics - JETP, V34, P874
[2]  
[Anonymous], 1936, BUR CENT SEISMOL INT
[3]   An ab initio molecular dynamics study of iron phases at high pressure and temperature [J].
Belonoshko, A. B. ;
Arapan, S. ;
Rosengren, A. .
JOURNAL OF PHYSICS-CONDENSED MATTER, 2011, 23 (48)
[4]   Shear Relaxation in Iron under the Conditions of Earth's Inner Core [J].
Belonoshko, A. B. ;
Bryk, T. ;
Rosengren, A. .
PHYSICAL REVIEW LETTERS, 2010, 104 (24)
[5]   Quenching of bcc-Fe from high to room temperature at high-pressure conditions: a molecular dynamics simulation [J].
Belonoshko, A. B. ;
Derlet, P. M. ;
Mikhaylushkin, A. S. ;
Simak, S. I. ;
Hellman, O. ;
Burakovsky, L. ;
Swift, D. C. ;
Johansson, B. .
NEW JOURNAL OF PHYSICS, 2009, 11
[6]   Quasi -: Ab initio molecular dynamic study of Fe melting [J].
Belonoshko, AB ;
Ahuja, R ;
Johansson, B .
PHYSICAL REVIEW LETTERS, 2000, 84 (16) :3638-3641
[7]   Stability of the body-centred-cubic phase of iron in the Earth's inner core [J].
Belonoshko, AB ;
Ahuja, R ;
Johansson, B .
NATURE, 2003, 424 (6952) :1032-1034
[8]   Elastic anisotropy of Earth's inner core [J].
Belonoshko, Anatoly B. ;
Skorodumova, Natalia V. ;
Rosengren, Anders ;
Johansson, Boerje .
SCIENCE, 2008, 319 (5864) :797-800
[9]   Origin of the low rigidity of the Earth's inner core [J].
Belonoshko, Anatoly B. ;
Skorodumova, Natalia V. ;
Davis, Sergio ;
Osiptsov, Alexander N. ;
Rosengren, Anders ;
Johansson, Boerje .
SCIENCE, 2007, 316 (5831) :1603-1605
[10]   Free energies of iron phases at high pressure and temperature: Molecular dynamics study [J].
Belonoshko, Anatoly B. ;
Fu, Jie ;
Smirnov, Grigory .
PHYSICAL REVIEW B, 2021, 104 (10)