X-ray Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA.
Nano Lett. 2010 Mar 10;10(3):799-803. doi: 10.1021/nl9029048.
Critical photonic, electronic, and magnetic applications of two-dimensional nanocrystal superlattices often require nanostructures in perfect single-crystal phases with long-range order and limited defects. Here we discovered a crystalline phase with quasi-long-range positional order for two-dimensional nanocrystal superlattice domains self-assembled at the liquid-air interface during droplet evaporation, using in situ time-resolved X-ray scattering along with rigorous theories on two dimensional crystal structures. Surprisingly, it was observed that drying these superlattice domains preserved only an orientational order but not a long-range positional order, also supported by quantitative analysis of transmission electron microscopy images.
二维纳米晶体超晶格的关键光子、电子和磁性应用通常需要具有长程有序和有限缺陷的完美单晶相的纳米结构。在这里，我们通过在液-气界面的液滴蒸发过程中利用原位时间分辨 X 射线散射以及二维晶体结构的严格理论，发现了二维纳米晶体超晶格畴在自组装时具有准长程位置有序的晶相。令人惊讶的是，我们发现，这些超晶格畴在干燥过程中仅保留了取向有序而不是长程位置有序，透射电子显微镜图像的定量分析也支持了这一结果。
