کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
10121285 | 1641614 | 2005 | 11 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
The axial ratio of hcp iron at the conditions of the Earth's inner core
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کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه
علوم زمین و سیارات
فیزیک زمین (ژئو فیزیک)
پیش نمایش صفحه اول مقاله
![عکس صفحه اول مقاله: The axial ratio of hcp iron at the conditions of the Earth's inner core The axial ratio of hcp iron at the conditions of the Earth's inner core](/preview/png/10121285.png)
چکیده انگلیسی
We present ab initio calculations of the high-temperature axial c /a ratio of hexagonal-close-packed (hcp) iron at Earth's core pressures, in order to help interpret the observed seismic anisotropy of the inner core. The calculations are based on density functional theory, which is known to predict the properties of high-pressure iron with good accuracy. The temperature dependence of c /a is determined by minimising the Helmholtz free energy at fixed volume and temperature, with thermal contributions due to lattice vibrations calculated using harmonic theory. Anharmonic corrections to the harmonic predictions are estimated from calculations of the thermal average stress obtained from ab initio molecular dynamics simulations of hcp iron at the conditions of the inner core. We find a very gradual increase of axial ratio with temperature. This increase is much smaller than found in earlier calculations, but is in reasonable agreement with recent high-pressure, high-temperature diffraction measurements. This result casts doubt on an earlier interpretation of the seismic anisotropy of the inner core.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Physics of the Earth and Planetary Interiors - Volume 152, Issues 1â2, 15 September 2005, Pages 67-77
Journal: Physics of the Earth and Planetary Interiors - Volume 152, Issues 1â2, 15 September 2005, Pages 67-77
نویسندگان
C.M. S. Gannarelli, D. Alfè, M.J. Gillan,