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.

中文翻译：

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通过电阻探测铁的熔化跃升至 135 GPa

兆巴压力下铁的熔化温度 ( T _m ) 限制了地核温度结构和动力学。以前的实验研究表明，在高压下T _m存在很大差异。我们使用跨固-液转变的固有电阻不连续性作为熔化标准来研究激光加热金刚石砧座中铁的熔化行为。电阻跳变对初始熔化很敏感，能够检测到小于 2 vol.% 的熔化物的出现。我们发现铁的高熔点曲线在 30-135 GPa，但慢-快再结晶的转变温度相对较低。确定的T _m铁在核幔边界（CMB）压力下为 4306（±300）K，与Anzellini 等人的静态和冲击波实验结果非常吻合。[2013] 和Li 等人。[2020]。铁的高熔点意味着高而陡的地温梯度，并影响穿过 CMB 的热流。