Time-resolved X-ray Studies of Kinetics of Metastable Materials

亚稳态材料动力学的时间分辨 X 射线研究

• 批准号: 8805156
• 负责人: Roy Clarke
• 金额: $ 19.37万
• 依托单位: Regents of the University of Michigan - Ann Arbor
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1988
• 资助国家: 美国
• 起止时间: 1988-11-01 至 1991-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8805156&HistoricalAwards=false
• 关键词: Time; resolved; ray; Studies; Kinetics

The use of materials in metastable states is becoming very pervasive in many technological applications. Very often the atomic arrangements in such cases have intermediate-range order somewhat characteristic of crystalline structure but they are not in true thermodynamic equilibrium. The kinetic behavior of metastable structures, and especially their relation to the equilibrium long-range ordered state, is quite poorly understood at present. There has been substantial progress in the theory of non-equilibrium processes using the concepts of kinetic critical phenomena, but little experimental work which probes directly the microscopic mechanisms. We propose a thorough study of this area utilizing powerful ne techniques in time-resolved x-ray diffuse scattering. The research exploits the recent developments in x-ray sources (very brightness synchrotron radiation) and detectors (fast two- dimensional CCDs) which are expected to revolutionize time- resolved studies. The goal of the research is to identify universal features of the kinetics which can be incorporated into a general quantitative description of non-equilibrium structural processes. Two model systems have been chosen for these studies; the research will focus on the rapid thermal annealing of thin- film heterostructures which have important optoelectronic applications, and the growth and relaxation mechanisms of electrochemically deposited dendrites and thin film structures.

在亚稳态状态下的材料在许多技术应用中变得非常普遍。 在这种情况下，原子布置通常具有晶体结构的中等范围，但它们不具有真正的热力学平衡。 目前对亚稳态结构的动力学行为，尤其是它们与均衡远程有序状态的关系，目前已经很糟糕。 使用动力学关键现象的概念，在非平衡过程的理论中取得了长足的进步，但是很少直接探测微观机制的实验性工作。 我们提出了一项彻底的研究，利用时间分辨X射线弥散散射的强大NE技术。 该研究利用了X射线源（非常亮度同步辐射）和检测器（快速两维CCD）的最新发展，这些进展有望彻底改变时间分解研究。 该研究的目的是确定动力学的通用特征，这些特征可以纳入非平衡结构过程的一般定量描述中。 这些研究已选择了两个模型系统。 该研究将集中于具有重要光电应用的薄膜异质结构的快速热退火，以及电化学沉积的树突和薄膜结构的生长和放松机制。