Pleomorphism and multidirectional combination of Si crystal nucleation during solidification

LX Li and TH Gao and Q Xie and Q Chen and ZA Tian and YC Liang and B Wang, JOURNAL OF MATERIALS SCIENCE, 56, 15960-15970 (2021).

DOI: 10.1007/s10853-021-06313-2

Research on the structural properties of silicon crystal nucleation during solidification has been the subject of numerous classic studies in condensed matter physics and material science. The approach to structural properties of Si crystal nucleation adopted for this paper is based on molecular dynamics simulation at the cooling rate of 10(10) K/s. Using the entropy of largest standard cluster and the pair distribution function, it is able to obtain microstructural evolution characteristics. The pleomorphism properties and distribution of Si crystal nucleation was presented by the visualization method. The systematic evolution diagram illustrates the competitive growth between cubic diamond and hexagonal diamond structures which shows that the crystal nucleus easily forms and then grow during a short period of time at the initial crystallization stage. The orientation characteristics after crystal nucleation in space are systematically analyzed and it is found that the nucleation and orientation of crystals are weakly dependent, that is, the orientations of crystals are homogeneous and random. In addition, the visualization results show that various twins exist in the system, including coherent twins, rotating twins and some torsional twins, which improve the structural stability to a certain degree. This study further explores crystal nucleation on the atomic scale and it is hoped that this research will contribute to expanding the understanding of the orientation distribution and crystallization behavior of amorphous silicon during the growth process.

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