资源环境科技发展态势分析平台

The melting temperature (T_m) of iron at megabar pressures constrain the Earth’s core temperature structure and dynamics. Previous experimental studies demonstrated large discrepancies in the T_m at high pressures. We used the intrinsic resistance discontinuity across solid-liquid transition as a melting criterion to study the melting behavior of iron in laser-heated diamond anvil cells. The resistance jump is sensitive to the incipient melting, capable of detecting the emergence of less than 2 vol.% melts. We found a high melting curve of iron at 30-135 GPa but a relatively low transition temperature of the slow-fast recrystallization. The determined T_m of iron is 4306(±300) K at the core-mantle boundary (CMB) pressure, in good agreement with the static and shockwave experimental results by Anzellini et al. [2013] and Li et al. [2020]. The high melting point of iron implies a high and steep geothermal gradient and influences heat flow across the CMB.