Abstract The atomistic mechanism for the structure conversion of FeSi from B20 to B2 phase at high pressures is a long-standing problem in Fe-Si system. Here we explore the atomistic mechanism about this intriguing structure conversion by first-principle calculations. We find the structure conversion from B20 to B2 is inhibited by the high kinetic barriers and the weak driving forces from low relative enthalpy under pressures. We also identify an orthorhombic structure with Pbcm symmetry as an intermediate meta-stable phase along the minimum energy path, which is possibly the precursory state of the B2 phase. These results can help to explain experimental findings and explore the kinetic origin of this intriguing structure conversion of FeSi at high pressure and temperature.

中文翻译：

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FeSi在压力下的结构转变机制

摘要 FeSi在高压下从B20相到B2相的结构转变的原子机制是Fe-Si体系中长期存在的问题。在这里，我们通过第一性原理计算探索有关这种有趣结构转换的原子机制。我们发现从 B20 到 B2 的结构转换受到高动力学势垒和压力下低相对焓的弱驱动力的抑制。我们还将具有 Pbcm 对称性的正交结构确定为沿最小能量路径的中间亚稳相，这可能是 B2 相的前体状态。这些结果有助于解释实验结果并探索这种有趣的 FeSi 在高压和高温下结构转化的动力学起源。