可控动态周期加载下时间分辨高压XAFS技术研究及其应用

Pressure，as one of the thermodynamic parameter,pay an important role to the materials' structure and fuctions.Now,there are a lots of intersting physical phenomena in the time scale between high pressure and shock-compression.Dynamic loading diamond anvil cell(dDAC) is a controllable pressure loading technique and is just in the gap mentioned above.This technique is very useful for the scientists to study the dynamic phenomena and to bulid the dynamic phase diagram under high pressure.It's also helpful for the scientists to get an insight into the materials' properties and to develop related theories.XAFS is a powerful tool which can get the local structure and the electronic structure informations of the specific element which is in amorphous materials or in a complicated systerm.In our research,we will develop the time-resolved high pressure XAFS technique composed of dDAC,XAFS and time-resolved method.By using this new technique,we could study the local structure information of the materials under the controllable dynamic periodic pressure loading situation.And we will apply this new technique to study Bismuth(an important simulalating material in the shock-compression region). We want to study its high pressure behaviour near the phase transition points under different dynamic pressure loading path.And to find out the correlation betweent the loading path and its local structure .

压力作为热力学参数之一，对材料的结构、性能等有重要的影响。目前，许多有趣的还未研究的物理现象处在静高压和动高压（冲击压缩）中间的时间尺度。动态加载金刚石压机（dDAC）作为一种完全可控的动态加载技术，恰好处在静高压与动高压的空白区域；对于研究在高压下发生的动力学现象和过程，建立与压缩率相关的动力学相图，深入理解材料的性质，以及发展相关的理论，具有十分重要的推动作用。XAFS实验技术是一种在高压下获取非晶态材料与复杂体系中特定元素的局域结构与电子结构信息的重要实验手段。因此，本课题拟结合dDAC实验技术、XAFS实验技术与时间分辨技术，开展可控动态周期加载下时间分辨高压XAFS技术研究，提供一种在可控动态周期加载下，材料的局域结构研究的探测方法。并应用该实验技术对金属铋（动高压的重要模拟材料）在不同加载路径下，各个相变点附近的高压行为进行研究；探究其局域结构、电子结构与加载路径之间的关系。