Melting of homogeneously superheated colloidal susensions: processes and their kinetics

均匀过热胶体悬浮液的熔化：过程及其动力学

• 批准号: 319917750
• 负责人: Professor Dr. Thomas Palberg
• 金额: --
• 依托单位: Institut für Physik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2016
• 资助国家: 德国
• 起止时间: 2015-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/319917750?language=en
• 关键词: Melting; homogeneously; superheated; colloidal; susensions

Up to recently, the phenomenology of the melting process was thought to be quite well understood. However, with the advent of laser pulse heating and increase in computing power, investigations of strongly superheated solids became feasible. Their results raised a number of interesting fundamental questions concerning the mechanisms and the kinetics of melting under conditions of homogeneous superheating. Here, we suggest to study the phenomenolgy of melting and to quantify its kinetics utilizing colloidal model suspensions. We will exploit the excellent optical accessibility due to the colloid specific time and length scales and use state of the art optical methods. In addition to polarization and Bragg microscopy we will employ Differential Dynamic Microskopie and time resolved Static Light Scattering. We will focus on two classes of electrostatically interacting aqueous suspensions, and we will vary their interaction in a controlled way by established experimental procedures: binary eutectic mixtures and thermosensitive particle-surfactant mixtures. In the latter case, the interaction strength and range can be adjusted using the temperature dependent adsorption equilibrium of the surfactants. In our preliminary studies we found a rich variety of different melting scenarios for both system classes. In the first funding period we plan to obtain a comprehensive overview and classification of the observable phenomena in their dependence on superheating as well as a quantitative determination of the corresponding nucleation, growth and coalescence kinetics. Later we will also address the microscopic mechanisms of melting using high resolution microscopy. The long term goal of our studies - taking a complementary view on melting under homogeneously superheated conditions - is a substantial contribution to a deepened, possibly quantitative understanding of the involved processes.

直到最近，熔化过程的现象学被认为是相当好的理解。然而，随着激光脉冲加热的出现和计算能力的提高，对强过热固体的研究变得可行。他们的结果提出了一些有趣的基本问题，涉及均匀过热条件下熔化的机理和动力学。在这里，我们建议研究熔化的现象，并利用胶体模型悬浮液来量化其动力学。我们将利用胶体特定的时间和长度尺度带来的良好的光学可达性，并使用最先进的光学方法。除了偏振显微镜和布拉格显微镜外，我们还将使用差动微视镜和时间分辨静态光散射。我们将集中在两类静电相互作用的水悬浮液上，我们将通过既定的实验程序来控制改变它们的相互作用：二元共晶混合物和热敏性粒子-表面活性剂混合物。在后一种情况下，可以利用表面活性剂随温度变化的吸附平衡来调节相互作用的强度和范围。在我们的初步研究中，我们发现了这两个系统类别的各种不同的熔化场景。在第一个资助期，我们计划对可观察到的现象对过热的依赖进行全面的概述和分类，并定量确定相应的成核、生长和合并动力学。稍后，我们还将使用高分辨率显微镜研究熔化的微观机制。我们研究的长期目标--对均匀过热条件下的熔化采取补充观点--是对深化、可能是对相关过程的定量理解的重大贡献。