研究使用从头算分子动力学模拟，发现在内核压力下，当温度高于铁熔点时，bcc相可以在液态镍中自发结晶。在323-360 GPa时，镍的熔点比铁的熔点高700-800 K。铁和镍的hcp、bcc和液相关系不同。在高温和内核压力下，镍可以作为铁的bcc稳定剂。少量的镍可以加速铁在核心压力下的结晶。
研究结果表明，镍可能会对固体内核的结构和形成过程产生实质性的影响。
据了解，镍是地核中含量第二丰富的元素。然而，由于其电子和尺寸与铁相似，其对内核结构和形成过程的影响通常被忽视。
附：英文原文
Title: Unveiling the effect of Ni on the formation and structure of Earth’s inner core
Author: Sun, Yang, Mendelev, Mikhail I., Zhang, Feng, Liu, Xun, Da, Bo, Wang, Cai-Zhuang, Wentzcovitch, Renata M., Ho, Kai-Ming
Issue&Volume: 2024-1-18
Abstract: 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.
DOI: 10.1073/pnas.2316477121
Source: https://www.pnas.org/doi/abs/10.1073/pnas.2316477121