Geodynamics Research Center, Ehime University, 2-5 Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan.
J Phys Condens Matter. 2023 May 2;35(30). doi: 10.1088/1361-648X/acce16.
The effects of iron (Fe) incorporation on the lattice thermal conductivity (κlat) of MgO are investigated under the Earth's lower mantle pressure () and temperature () condition (> ∼20 GPa,> ∼2000 K) based on the density-functional theory combined with the anharmonic lattice dynamics theory. Theκlatof ferropericlase (FP) is determined combining the internally consistent LDA +method and self-consistent approach to solve the phonon Boltzmann transport equation. The calculatedκlatare well fitted to the extended Slack model which is proposed in this study to representκlatin a wide volume andrange. Results demonstrate that theκlatof MgO decreases strongly by Fe incorporation. This strong negative effect is found due to decreases in phonon group velocity and lifetime. Consequently, theκlatof MgO at the core-mantle boundary condition (∼ 136 GPa,∼ 4000 K) is substantially reduced from ∼40 to ∼10 W mKby the incorporation of Fe (12.5 mol%). The effect of Fe incorporation on theκlatof MgO is found to be insensitive toand, and at high, theκlatof FP obeys a well-establishedinverse relation unlike the experimental observations.
基于密度泛函理论结合非谐晶格动力学理论，研究了在地球下地幔压力（）和温度（）条件（> ∼20 GPa，> ∼2000 K）下，铁（Fe）掺入对氧化镁（MgO）晶格热导率（κlat）的影响。结合内部一致的 LDA +方法和自洽方法求解声子玻尔兹曼输运方程，确定了钙钛矿（FP）的κlat。计算出的κlat很好地符合了本研究中提出的扩展 Slack 模型，以代表在广泛的体积和范围内的 κlat。结果表明，Fe 的掺入强烈降低了 MgO 的 κlat。这种强烈的负效应是由于声子群速度和寿命的降低而导致的。因此，在核幔边界条件（∼ 136 GPa，∼ 4000 K）下，Fe（12.5 mol%）掺入使 MgO 的 κlat 从 ∼40 降低到 ∼10 W mK。发现 Fe 掺入对 MgO 的 κlat 的影响对和不敏感，而在高时，FP 的 κlat 遵循一个既定的反比关系，这与实验观察结果不同。
