论文标题
量化的晶界状态在不完美的附件期间促进纳米颗粒对齐
Quantized grain boundary states promote nanoparticle alignment during imperfect oriented attachment
论文作者
论文摘要
定向附着（OA）已成为金属，陶瓷和生物矿物晶体生长的良好认可的机制。尽管OA的许多计算和实验研究表明，颗粒可以与某些不良方向附着，然后旋转以去除相邻的晶界，但这种“不完美的OA”过程的基本原子途径仍然是争论的主题。在这项研究中，分子动力学和原位TEM用于探测聚集过程中多达30颗金和铜纳米颗粒的晶体学演化。发现发生不完善的OA发生是因为（1）当晶界的大小与构成位错之间的分离相当时，晶界被量化，并且（2）与晶界位错滑动相关的动力学屏障很小。为了支持这些发现，TEM实验表明在退火9最初是不良的，凝聚的颗粒后具有单个晶体聚集体的形成，并在粒子/晶粒对齐过程中具有脱位滑移和双胞胎形成的证据。这些观察结果激发了未来在纳米晶体中组装的纳米晶体上的工作，并呼吁修改纳米晶材料中晶粒边界能量的读取索克利模型。
Oriented attachment (OA) has become a well-recognized mechanism for the growth of metal, ceramic, and biomineral crystals. While many computational and experimental studies of OA have shown that particles can attach with some misorientation then rotate to remove adjoining grain boundaries, the underlying atomistic pathways for this "Imperfect OA" process remain the subject of debate. In this study, molecular dynamics and in situ TEM were used to probe the crystallographic evolution of up to 30 gold and copper nanoparticles during aggregation. It was found that Imperfect OA occurs because (1) grain boundaries become quantized when their size is comparable to the separation between constituent dislocations and (2) kinetic barriers associated with the glide of grain boundary dislocations are small. In support of these findings, TEM experiments show the formation of a single crystal aggregate after annealing 9 initially misoriented, agglomerated particles with evidence of dislocation slip and twin formation during particle/grain alignment. These observations motivate future work on assembled nanocrystals with tailored defects and call for a revision of Read-Shockley models for grain boundary energies in nanocrystalline materials.
