Thermal conductivity of dense hcp iron: Direct measurements using laser heated diamond anvil cell

Abstract

Thermal conductivity (k) of iron is measured up to about 134 ​GPa. The measurements are carried out using the single sided laser heated diamond anvil cell, where the power absorbed by a Fe metal foil at hotspot is calculated using a novel thermodynamical method. Thermal conductivity of fcc (γ) ​− ​Fe increases up to a pressure of about 46 ​GPa. We find thermal conductivity values in the range of 70–80 Wm−1K−1 (with an uncertainty of 40%), almost constant with pressure, in the hcp (ε) phase of Fe. We attribute the pressure independent k above 46 ​GPa to the strong electronic correlation effects driven by the electronic topological transition (ETT). We predict a value of thermal conductivity of ε -Fe of about 40 ​± ​16 Wm−1K−1 ​at the outer core of Earth.