内核/壳层微结构上应力驱动的三角和斐波纳契数花样

Self-assembly on core/shell microstructures driven by stress into triangular and Fibonacci number patterns

自然界中三角和斐波纳契数的叶序花样随处可见.通过控制几何条件以及冷却之后产生的应力,这些花样能在Ag内核/SiOx壳层微结构(约10μm大小)上予以实现.在这种内核/壳结构表面上,大小形状十分一致的小球通过自组装是形成斐波纳契数花样(我们观察到5×8,8×13和13×21三种)还是三角花样,取决于基座面的几何构形.作者工作的意义在于揭示了在适当的几何约束下,自组装形成的花样是总应变能最小的结果.这对叶序花样的形成来源提出了一种非遗传的机理.此外,作者的研究表明,高度有序的、甚至含有内禀缺陷的微结构可以通过应力工程在大面积范围内同时得到.

Triangular and Fibonacci number phyllotactic patterns in nature have attracted much interest a- mongst scientists in multidisciplinary fields. By controlling the geometty along with the stress developed during cooling, these patterns can be reproduced on the surface of Ag core/SiOx shell microstructures. The significance of our work lies in the revelation that, under proper geometrical constraint, the various patterns can develop through minimization of the strain energy. This provides a physical mechanism without involving the growth dynamics of the formation of phyllotactic patterns. Moreover, it demonstrates that highly-ordered microstructures, even with desirable defects, can be prepared across large areas simultaneously by stress engineering.