论文标题
预购液体在成核过程中晶体多晶型物的选择机理中的作用
Role of pre-ordered liquid in the selection mechanism of crystal polymorphs during nucleation
论文作者
论文摘要
我们研究了使用过渡路径采样的钼期间固化过程中均质成核的原子机制。该机理的特征在于在超冷液体中形成高键取向阶的预制区域，然后在生长固体簇的中心内的结晶体相成核。该前体在该过程中起着至关重要的作用，因为它提供了液体和晶体之间的扩散界面，从而降低了界面自由能并促进块相的成核。此外，预排序区域的结构特征与液相和固体相位，并预先选择成核的特定多晶型物。 MO的成核机制与表现出不同晶体体相的金属的相似性表明，前体的形成是这些材料中观察到的一般特征。前体的结构特征对最终结晶相的强大影响表明，对于所研究的系统，选择性选择发生在成核的早期阶段。
We investigate the atomistic mechanism of homogeneous nucleation during solidification in molybdenum employing transition path sampling. The mechanism is characterized by the formation of a pre-structured region of high bond-orientational order in the supercooled liquid followed by the nucleation of the crystalline bulk phase within the center of the growing solid cluster. This precursor plays a crucial role in the process, as it provides a diffusive interface between the liquid and crystalline core, which lowers the interfacial free energy and facilitates the nucleation of the bulk phase. Furthermore, the structural features of the pre-ordered regions are distinct from the liquid and solid phases, and preselect the specific polymorph that nucleates. The similarity in the nucleation mechanism of Mo with that of metals that exhibit different crystalline bulk phases indicates that the formation of a precursor is a general feature observed in these materials. The strong influence of the structural characteristics of the precursors on the final crystalline bulk phase demonstrates that for the investigated system polymorph selection takes place in the very early stages of nucleation.
