Demchenko Denis O, Robinson Richard D, Sadtler Bryce, Erdonmez Can K, Alivisatos A Paul, Wang Lin-Wang
Computational Research Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
ACS Nano. 2008 Apr;2(4):627-36. doi: 10.1021/nn700381y.
The mechanism of formation of recently fabricated CdS-Ag(2)S nanorod superlattices is considered and their elastic properties are predicted theoretically based on experimental structural data. We consider different possible mechanisms for the spontaneous ordering observed in these 1D nanostructures, such as diffusion-limited growth and ordering due to epitaxial strain. A simplified model suggests that diffusion-limited growth partially contributes to the observed ordering, but cannot account for the full extent of the ordering alone. The elastic properties of bulk Ag(2)S are predicted using a first principles method and are fed into a classical valence force field (VFF) model of the nanostructure. The VFF results show significant repulsion between Ag(2)S segments, strongly suggesting that the interplay between the chemical interface energy and strain due to the lattice mismatch between the two materials drives the spontaneous pattern formation.
本文考虑了最近制备的CdS-Ag₂S纳米棒超晶格的形成机制，并基于实验结构数据对其弹性性质进行了理论预测。我们考虑了在这些一维纳米结构中观察到的自发有序排列的不同可能机制，如扩散限制生长和外延应变导致的有序排列。一个简化模型表明，扩散限制生长部分促成了观察到的有序排列，但仅靠它无法解释有序排列的全部情况。使用第一性原理方法预测了块状Ag₂S的弹性性质，并将其输入到纳米结构的经典价键力场（VFF）模型中。VFF结果显示Ag₂S段之间存在显著的排斥力，强烈表明两种材料之间晶格失配导致的化学界面能和应变之间的相互作用驱动了自发图案的形成。
