Measurements of Electrical and Thermal Conductivity of Iron Under Earth’s Core Conditions

Tuesday, 16 December 2014: 9:15 AM
Kenji Ohta, Tokyo Institute of Technology, Tokyo, Japan, Yasuhiro Kuwayama, Ehime University, Ehime, Japan, Katsuya Shimizu, Osaka University, Osaka, Japan, Takashi Yagi, AIST - National Institute of Advanced Industrial Science and Technology, Tsukuba, Japan, Kei Hirose, Earth-Life Science Institute, Meguro, Japan and Yasuo Ohishi, Japan Synchrotron Radiation Research Institute, Hyogo, Japan
Secular cooling of the Earth’s core induces the convection of the conductive liquid outer core, which generates the geomagnetic field, and the growth of the solid inner core. Since iron is the primary component of the Earth’s core, the electrical and thermal conductivity of iron in both solid and liquid states are key pieces of information for estimating the transport properties of the core. We performed electrical and thermal conductivity measurements on iron under core conditions in a laser-heated diamond anvil cell. Our electrical conductivity measurements on iron clearly show resistivity saturation phenomena in iron under high pressure and high temperature conditions as predicted in a recent laboratory-based model for the core conductivity (Gomi et al., 2013). Direct measurements of thermal diffusivity of iron have been also preformed at high pressures by using the pulsed light heating thermoreflectance technique, which enable us to confirm the validity of the Wiedemann-Franz law toward transition metal under high pressure.