Townsend Eleanor R, van Enckevort Willem J P, Tinnemans Paul, Blijlevens Melian A R, Meijer Jan A M, Vlieg Elias
Radboud University, Institute for Molecules and Materials, 6500 GL Nijmegen, The Netherlands.
AkzoNobel Industrial Chemicals, RD&I Salt, 7418 AJ Deventer, The Netherlands.
Cryst Growth Des. 2018 Feb 7;18(2):755-762. doi: 10.1021/acs.cgd.7b01170. Epub 2017 Dec 8.
A multitude of ultrathin crystal needles are formed during the evaporation of saturated aqueous NaCl solution droplets in the presence of amide containing additives. The needles are as small as 300 nm wide and 100-1000 μm in length. Heating experiments, X-ray diffraction, and energy dispersive X-ray spectroscopy showed that the needles are cubic sodium chloride crystals with the needle length direction pointing toward [100]. This shape, not expected for the 43̅ point group symmetry of NaCl, has been explained using a model, based on tip formation by initial morphological instability followed by time dependent adsorption of additive molecules blocking the growth of the needle side faces. The latter also suppresses side branch formation, which normally occurs for dendrite growth.
在含有酰胺添加剂的情况下，饱和氯化钠水溶液液滴蒸发过程中会形成大量超薄晶体针。这些针宽小至300纳米，长度为100 - 1000微米。加热实验、X射线衍射和能量色散X射线光谱表明，这些针是立方氯化钠晶体，针的长度方向指向[100]。这种形状对于氯化钠的43̅点群对称性来说是出乎意料的，已使用一个模型进行了解释，该模型基于初始形态不稳定性导致的尖端形成，随后添加剂分子随时间的吸附阻止了针侧面的生长。后者还抑制了通常在枝晶生长中出现的侧枝形成。
