Pariente Jose Ángel, Blanco Álvaro, López Cefe
Consejo Superior de Investigaciones Científicas (CSIC), Instituto de Ciencia de Materiales de Madrid (ICMM), Calle Sor Juana Inés de la Cruz 3, E-28049 Madrid, Spain.
Nanophotonics. 2022 Jun 9;11(14):3257-3267. doi: 10.1515/nanoph-2022-0127. eCollection 2022 Jul.
Colloidal suspensions crystallize by a natural sedimentation process under certain conditions, the initial volume fraction being one of the parameters that govern this process. Here, we have developed a simple , real-time, optical characterization technique to study silica colloidal suspensions during natural sedimentation in order to shed new light on this crystallization process. This technique monitors small variations in the wavelength of the reflectance features, allowing the analysis of the formation of the first layers of the crystal with sub-nanometer precision, and their dynamics, which is crucial to ensure a high quality in the final sample. The experimental results indicate that, in certain range of volume fraction, spontaneous crystallization of a colloidal fluid occurs at the bottom of the suspension, as a phase change, then through evaporation of the water it compacts to near close-packed and, eventually, dries. Understanding self-assembly at these scales is paramount in materials science and our results will contribute to improve and characterize the quality and crystallinity of the materials used in this process.
在某些条件下，胶体悬浮液通过自然沉降过程结晶，初始体积分数是控制此过程的参数之一。在此，我们开发了一种简单、实时的光学表征技术，用于研究二氧化硅胶体悬浮液在自然沉降过程中的情况，以便为这一结晶过程提供新的见解。该技术监测反射特征波长的微小变化，能够以亚纳米精度分析晶体第一层的形成及其动力学，这对于确保最终样品的高质量至关重要。实验结果表明，在一定体积分数范围内，胶体流体在悬浮液底部发生自发结晶，这是一种相变，然后通过水的蒸发使其压实至接近密堆积状态，最终干燥。了解这些尺度下的自组装在材料科学中至关重要，我们的结果将有助于改进和表征此过程中所用材料的质量和结晶度。
