Irina Chuvashova, Carnegie Science
Thermal Conductivity of Earth Minerals at Extreme Conditions
Written by Tianyu Liu
The thermal conductivity of the lower mantle of Earth has been experimentally estimated. The lower mantle is a solid mineral layer that could let heat pass. Various methods have been proposed to quantify the thermal conductivity, or heat-conducting rate, of Earth’s lower mantle; however, experimental evidence remains scarce. Irina Chuvashova from Carnegie Science has added an experimental data of 12.6 W/(m K).
Chuvashova and co-workers adopted a diamond anvil cell to determine the thermal conductivities of two main iron-bearing minerals in the lower mantle, Ferropericlase and Bridgmanite, under high pressure. The researchers placed the mineral films between two diamond crystals. Due to the hardness, the two diamond crystals could exert ultrahigh forces from 25 GPa to 60 GPa onto the films without cracking. Ultrahigh pressure is necessary to mimic the high-pressure environment inside the Earth. Through black-body theory and laser heating, Chuvashova and co-workers calculated that the thermal conductivities of Ferropericlase and Bridgmanite were 43 W/(m K) and 5 W/(m K), respectively, at 40 GPa. Considering the amount of the two minerals in the lower mantle, the researchers estimated that the lower mantle possessed a thermal conductivity of 12.6 W/(m K), close to the theoretical values.