Thermal and electrical conductivity of solid iron and iron-silicon mixtures at Earth's core conditions
Thermal and electrical conductivity of solid iron and iron-silicon mixtures at Earth's core conditions
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DOI：
10.1016/j.epsl.2014.02.047
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发表时间：
2014-05-01
影响因子：
5.3
通讯作者：
Alfe, Dario
中科院分区：
文献类型：
--
作者：
Pozzo, Monica;Davies, Chris;Alfe, Dario
本文报道了在相关压力-温度条件下代表地球固体内核组成的固体铁和铁硅混合物（Fe0.92Si0.08和Fe0.93Si0.07）的热导率和电导率，由密度泛函理论用Kubo-Greenwood公式计算得到。我们发现，在内核（地球中心）的顶部，导热系数k = 232 (237) Wm(-1) k -1，电导率sigma = 1.5 (1.6) Chi 10(6) Omega(-1) m（-1）。这些数值分别比液态外岩心的相应电导率高45-56%和18-25%。较高的电导率是由于固体结构和较低浓度的轻杂质。这些值比以前的内核研究中使用的值高得多，k是4倍，sigma是3倍。高导热率意味着热量通过传导泄漏出去的速度几乎和内核形成的速度一样快，这使得热对流不太可能。高导电性使内芯的磁衰减时间增加了三倍以上，将磁扩散时间延长到10 kyr，使内芯更有可能稳定地球发电机并减少反转的频率。(C) 2014 Elsevier B.V.这是一篇基于CC BY许可的开放获取文章
We report on the thermal and electrical conductivities of solid iron and iron-silicon mixtures (Fe0.92Si0.08 and Fe0.93Si0.07), representative of the composition of the Earth's solid inner core at the relevant pressure-temperature conditions, obtained from density functional theory calculations with the Kubo-Greenwood formulation. We find thermal conductivities k = 232 (237) Wm(-1) K-1, and electrical conductivities sigma = 1.5 (1.6) Chi 10(6) Omega(-1) m(-1) at the top of the inner core (centre of the Earth). These values are respectively about 45-56% and 18-25% higher than the corresponding conductivities in the liquid outer core. The higher conductivities are due to the solid structure and to the lower concentration of light impurities. These values are much higher than those in use for previous inner core studies, k by a factor of four and sigma by a factor of three. The high thermal conductivity means that heat leaks out by conduction almost as quickly as the inner core forms, making thermal convection unlikely. The high electrical conductivity increases the magnetic decay time of the inner core by a factor of more than three, lengthening the magnetic diffusion time to 10 kyr and making it more likely that the inner core stabilises the geodynamo and reduces the frequency of reversals. (C) 2014 Elsevier B.V. This is an open access article under the CC BY license