Martín-Roca José, Horcajo-Fernández Manuel, Valeriani Chantal, Gámez Francisco, Martínez-Pedrero Fernando
Departamento de Estructura de la Materia, Física Térmica y Electrónica, Universidad Complutense de Madrid, 28040 Madrid, Spain.
GISC-Grupo Interdisciplinar de Sistemas Complejos, 28040 Madrid, Spain.
Nanomaterials (Basel). 2023 Jan 18;13(3):397. doi: 10.3390/nano13030397.
Two-dimensional colloidal crystals are of considerable fundamental and practical importance. However, their quality is often low due to the widespread presence of domain walls and defects. In this work, we explored the annealing process undergone by monolayers of superparamagnetic colloids adsorbed onto fluid interfaces in the presence of magnetic field pulses. These systems present the extraordinary peculiarity that both the extent and the character of interparticle interactions can be adjusted at will by simply varying the strength and orientation of the applied field so that the application of field pulses results in a sudden input of energy. Specifically, we have studied the effect of polycrystal size, pulse duration, slope and frequency on the efficiency of the annealing process and found that (i) this strategy is only effective when the polycrystal consists of less than approximately 10 domains; (ii) that the pulse duration should be of the order of magnitude of the time required for the outer particles to travel one diameter during the heating step; (iii) that the quality of larger polycrystals can be slightly improved by applying tilted pulses. The experimental results were corroborated by Brownian dynamics simulations.
二维胶体晶体具有相当重要的基础和实际意义。然而，由于畴壁和缺陷的普遍存在，它们的质量往往较低。在这项工作中，我们探索了在磁场脉冲存在下吸附在流体界面上的超顺磁性胶体单层所经历的退火过程。这些系统具有非凡的特性，即通过简单地改变外加磁场的强度和方向，可以随意调整粒子间相互作用的程度和性质，从而使磁场脉冲的施加导致能量的突然输入。具体而言，我们研究了多晶体尺寸、脉冲持续时间、斜率和频率对退火过程效率的影响，发现：（i）该策略仅在多晶体由少于约10个畴组成时有效；（ii）脉冲持续时间应与加热步骤中外层粒子移动一个直径所需的时间量级相同；（iii）通过施加倾斜脉冲可以略微提高较大多晶体的质量。实验结果得到了布朗动力学模拟的证实。
