高温高压下铁热导率的第一性原理研究

The thermal conductivity of iron under high pressure and high temperature from first-principles studies

铁在高压高温下的热导率是研究地球动力学和热演化的关键参数.在以往的研究中,铁的热导率主要归结于电子热导率,我们发现铁在高压下晶格振动对热导率的贡献不可忽略.本文利用晶格动力学和玻尔兹曼输运理论计算了铁的声子色散、Hugoniot状态方程和热导率.预测了铁在核幔边界附近温度约为3500 K,在地球内核边界条件约为6500 K.考虑晶格振动的热导率在地球核幔边界附近为112 W/mK,在内核边界条件约为200 W/mK.

Thermal conductivities of iron at high pressure and temperature are key parameters to constrain the dynamics and thermal evolution of the Earth’s core.In previous investigations,the thermal conductivity is mainly attributed to the electronic conductivity,we found that the contribution of lattice vibration to thermal conductivity under high pressure cannot be ignored.The phonon dispersion,Hugoniot equation of state and thermal transport properties of iron are calculated with the lattice dynamics and Boltzmann transport theory in this work.The simulation temperature for iron is 3500 K near the core-mantle boundary and 6500 K at Earth’s inner core conditions.The thermal conductivities considering lattice vibration are respectively 112 W/mK near the core-mantle boundary and 200 W/mK at Earth’s inner core conditions.