Unveiling the effect of Ni on the formation and structure of Earth's inner core

• 成果类型: Article
• 署名作者: Sun, Yang; Mendelev, Mikhail I.; Zhang, Feng; Liu, Xun; Da, Bo; Wang, Cai-Zhuang; Wentzcovitch, Renata M.; Ho, Kai-Ming
• 署名单位: Xiamen University; Columbia University; Iowa State University; National Institute for Materials Science; Columbia University; Columbia University; Columbia University; Simons Foundation; Flatiron Institute
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-10960
• DOI: 10.1073/pnas.2316477121
• 发表日期: 2024-01-23
• 关键词: centered-cubic iron; phase-relations; high-pressures; melting curve; fe; nickel; alloys; stabilization; temperature; simulations

摘要

Ni is the second most abundant element in the Earth's core. Yet, its effects on the inner core's structure and formation process are usually disregarded because of its electronic and size similarity with Fe. Using ab initio molecular dynamics simulations, we find that the bcc phase can spontaneously crystallize in liquid Ni at temperatures above Fe's melting point at inner core pressures. The melting temperature of Ni is shown to be 700 to 800 K higher than that of Fe at 323 to 360 GPa. hcp, bcc, and liquid phase relations differ for Fe and Ni. Ni can be a bcc stabilizer for Fe at high temperatures and inner core pressures. A small amount of Ni can accelerate Fe's crystallization at core pressures. These results suggest that Ni may substantially impact the structure and formation process of the solid inner core.