Searching for high magnetization density in bulk Fe: the new metastable Fe-6 phase
Searching for high magnetization density in bulk Fe: the new metastable Fe-6 phase
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寻找块状 Fe 的高磁化密度：新的亚稳态 Fe-6 相
DOI：
10.1088/0953-8984/27/1/016001
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发表时间：
2015
影响因子：
2.7
通讯作者：
M. Cococcioni
中科院分区：
文献类型：
--
作者：
K. Umemoto;B. Himmetoglu;J. P. Wang;R. M. Wentzcovitch;M. Cococcioni
我们报道用第一性原理计算发现了一种新的铁的同素异形体。该相具有Pmn21对称性，六原子晶胞(因此得名Fe6)，是已知的铁晶相中磁化强度最高的(M S)。Pmn2-1Fe6是Fe3C-渗碳体晶体脱碳后结构优化的结果，它是铁磁性面心立方相稳定的结果，并沿贝恩路径进一步应变。尽管新相在0-50 Gpa范围内处于亚稳状态，但在低压下比其他已知的hcp和fcc同素异形体更稳定，并在压缩下顺利转变为fcc相。例如，如果通过间隙杂质稳定到室温，Fe6可能成为高M S无稀土永磁体和高冲击应用(如轻型电动发动机转子或高密度记录介质)的基础材料。新相也可能是解释神秘的Fe16N2高M S的关键，该高M目前正吸引着激烈的研究活动。
We report the discovery of a new allotrope of iron by first principles calculations. This phase has Pmn2 1 symmetry, a six-atom unit cell (hence the name Fe 6), and the highest magnetization density (M s) among all the known crystalline phases of iron. Obtained from the structural optimizations of the Fe 3 C-cementite crystal upon carbon removal, Pmn2 1 Fe 6 is shown to result from the stabilization of a ferromagnetic FCC phase, further strained along the Bain path. Although metastable from 0 to 50 GPa, the new phase is more stable at low pressures than the other well-known HCP and FCC allotropes and smoothly transforms into the FCC phase under compression. If stabilized to room temperature, for example, by interstitial impurities, Fe 6 could become the basis material for high M s rare-earth-free permament magnets and high-impact applications such as light-weight electric engine rotors or high-density recording media. The new phase could also be key to explaining the enigmatic high M s of Fe 16 N 2, which is currently attracting intense research activity.