▲作者：Myoung Hwan Oh, Min Gee Cho, Dong Young Chung, Inchul Park, etc.
▲連結：
https://www.nature.com/articles/s41586-019-1899-3
▲ 摘要：
晶界相關的拓撲缺陷（GB缺陷）對納米晶材料在電學、光學、磁性、力學和化學性能方面的影響是眾所周知的。
在此，我們證明了對膠體多面納米晶體異質外延的精確控制能夠使晶粒有序生長，從而產生具有相同GB缺陷的材料樣品。
我們確定了控制這些高度有序的多晶粒納米結構生產的4個設計原理。
首先，基板納米晶體的形狀必須指引過度生長階段的晶體取向。第二，基板的尺寸必須小於位錯之間的特徵距離。
第三，過度生長期和基板之間的不對稱加劇了晶粒間的幾何失配應變。第四，對於近平衡條件下形成的晶界，需要通過配體鈍化增強彈性能來平衡外部的表面能。
根據這些原理，我們可以生產一系列含有明顯晶界缺陷的多晶粒納米晶體。
▲ Abstract
The impact of topological defects associated with grain boundaries (GB defects) on theelectrical, optical, magnetic, mechanical and chemical properties of nanocrystalline materials is well known. Here we demonstrate that precise control of the heteroepitaxy of colloidal polyhedral nanocrystals enables ordered grain growth and can thereby produce material samples with uniform GB defects. We identify four design principles that govern the production of these highly ordered multigrain nanostructures. First, the shape of the substrate nanocrystal must guide the crystallographic orientation of the overgrowth phase. Second, the size of the substrate must be smaller than the characteristic distance between the dislocations. Third, the incompatible symmetry between the overgrowth phase and the substrate increases the geometric misfit strain between the grains. Fourth, for GB formation under near-equilibrium conditions, the surface energy of the shell needs to be balanced by the increasing elastic energy through ligand passivation. With these principles, we can produce a range of multigrain nanocrystals containing distinct GB defects.