报告题目： 铁在地球核心条件下的稳定性研究
报告人： 王保田


日期：2013年12月27日 星期五
时间：14:30-15:30
地点：物电学院报告厅


报 告 摘 要
Earth's inner core, consists predominantly of iron, is under extreme pressures that range from 330 to 364 GPa with melting temperatures from 6000 up to 8000 K. Although considerable efforts have been contributed, there is still no direct experimental proof of the hexagonal close packed (hcp) to body-centered-cubic (bcc) phase transition under these extreme conditions as suggested by the theoretical study [A. B. Belonoshko, R. Ahuja, and B. Johansson, Nature 424, 1032 (2003)]. Here, we report results of iron by the self-consistent ab initio lattice dynamics, in which the phonon-phonon interactions are included. Phonon spectra, phonon free energy, and Gibbs free energy of the bcc and hcp phases are obtained under the high-pressure high-temperature (HP-HT) conditions. In addition to the calculated positive phonon spectra indicating dynamically stable of the bcc phase, comparison of the Gibbs free energy confirms that the thermodynamically stable phase of iron in the Earth's solid inner core is bcc structure.