在200 GPa冲击压强下铁是否会发生固-固相变?

Does There Exist a Solid-Solid Transformation in Shocked Iron at around 200 GPa ?

根据Grüneisen物态方程、Hugoniot内能守恒方程和最新发表的铁的热物理参数，计算了ε-（hcp）铁和液态铁的理论Hugoniot曲线。计算的Hugoniot曲线与最新修正的铁的实验数据[J Appl Phys，2000，88：5496]在总体上符合很好，并且可以细分为两个部分：在约低于200GPa的压强区，用ε-铁模型的计算结果与实验结果符合很好；在约高于260GPa的压强区，用液态铁模型的计算结果与实验数据也符合得比较好；对介于200-260GPa之间的压强区，则归属于由ε-铁向液态铁转变的混合相区。这意味着铁的Hugoniot曲线在约200GPa处出现的微小偏折是由固一液相变引起的，从而否定了Brown[Geophy Res Lett，2001，28：4339]提出的它是一次由ε-铁向另一个未知结构的某个固相铁的相转变的见解。

A theoretical Hugoniot curve of iron has been calculated based on Gr/Jneisen equation of state and internal energy conservation consideration, using a set of optimized or thermophysical parameters and both ε- and liquid-iron models. This determined Hugoniot curve is well in accord with the revised Hugoniot data [J Appl Phys,2000,88：5496] on the whole,and could be further divided into two parts. The first one can well describe the revised data below -200 GPa with ε-phase model, while the second can approxi- mately replicate the revised data above -260 GPa with liquid-phase model. It is thus convinced that the range between -200 GPa and -260 GPa should be in solid/liquid mixed state,i, e,a small kink appearing on the revised Hugoniot at -200 GPa is due to a solid-liquid transition,rather than a solid-solid transition at -200 GPa that was inferred from Brown＇s analysis [Geophys Res Lett,2001,28：4339].