Phase Stability and Thermal Equation of State of Iron Carbide Fe 3 C to 245 GPa
Phase Stability and Thermal Equation of State of Iron Carbide Fe 3 C to 245 GPa
复制标题
碳化铁 Fe 3 C 至 245 GPa 的相稳定性和状态热方程
DOI：
10.1029/2019gl084545
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发表时间：
2019
影响因子：
5.2
通讯作者：
Zhang, Mingjian
中科院分区：
文献类型：
--
作者：
Hu, Xiaojun;Fei, Yingwei;Yang, Jing;Cai, Yang;Ye, Shijia;Qi, Meilan;Liu, Fusheng;Zhang, Mingjian
我们对碳化铁 Fe3C 进行了高达 245 GPa 的 Hugoniot 压力的冲击波实验。粒子速度（up）与冲击波速度（us）之间可以拟合成线性关系，us=4.627（±0.073）+1.614（±0.028）up。密度-压力关系与不分解的单相压缩一致。观察到的休格尼奥密度与计算的可能分解产物的休格尼奥曲线的比较进一步支持了这一推论。新的 Hugoniot 数据与报告的 300-K 等温压缩数据相结合，得出的 Grüneisen 参数为 γ= 2.23(7.982/ρ)0.29。 Fe3C 的热状态方程进一步用于计算 Fe3C 沿地球绝热地温的密度分布。 Fe3C 的密度被发现太低（约 5%），无法与地球内核中观测到的密度相匹配，并且 Fe3C 不太可能是内核的主要成分。
We conducted shock wave experiments on iron carbide Fe3C up to a Hugoniot pressure of 245 GPa. The correlation between the particle velocity (up) and shock wave velocity (us) can be fitted into a linear relationship,us= 4.627(±0.073) + 1.614(±0.028)up. The density‐pressure relationship is consistent with a single‐phase compression without decomposition. The inference is further supported by the comparison of the observed Hugoniot density with the calculated Hugoniot curves of possible decomposition products. The new Hugoniot data combined with the reported 300‐K isothermal compression data yielded a Grüneisen parameter ofγ= 2.23(7.982/ρ)0.29. The thermal equation of state of Fe3C is further used to calculate the density profile of Fe3C along the Earth's adiabatic geotherm. The density of Fe3C was found to be too low (by ~5%) to match the observed density in the Earth's inner core, and Fe3C is unlikely a dominant component of the inner core.