Ab initio calculations on thermal conductivity of Fe-Ni-O fluid: Constraints on the thermal evolution of Earth's core

Abstract

Thermal conductivity is a crucial parameter for the thermal evolution of Earth's core. In this paper, the thermal conductivity of Fe-Ni-O fluid was calculated by ab initio simulations, and then age of inner core and thickness of thermal stratification were derived. The results indicate that the thermal conductivity of Fe-Ni-O fluid along the core adiabatic curve ranges from 111.68 to 182.33 W/m/K. The thermal conductivity at the core-mantle boundary increases monotonically with temperature as expected. The thermal conductivity of Fe-Ni-O fluid is lower than that of pure Fe and Fe-Ni fluids. The age of the inner core is determined to be 0.868 Ga in our fiducial model by calculating the energy budget in the core and time evolution of thermal conductivity of Fe-Ni-O fluid. The thickness of thermal stratification is 454 km when dTc/dt=100 K/Ga by calculating the temperature gradient.