High-pressure and high-temperature studies: structural evolution and phase transitions in minerals and their effect on intrinsic properties

矿物的稳定性和它们在地球深处的晶体结构中的原子排列的基本知识对于提供地球过程的现实模型是重要的。这个研究项目试图回答这个问题，为什么固体材料具有它们所展示的特性？这些性质在不同的压力和温度（P和T）条件下是如何变化的？结构中原子的顺序如何随P和T的变化而变化？有序-无序对内在性质的影响是什么？物理、机械、热力学、弹性和化学性质都是由固体中原子在原子尺度上的排列决定的。因此，有必要使用多学科方法和各种原位实验技术来确定包括矿物在内的材料的原子结构，以研究在非环境（不同的P和T）条件下（包括成分和时间）控制其稳定性和性质的过程，并将结果应用于矿物物理和地球过程。申请人是一名成熟的同步辐射研究人员，他在美国和法国的国家设施（APS， NSLS和ESRF）使用了最先进的实验技术，并希望在萨斯卡通的加拿大光源（CLS）使用或建立类似的技术。我的研究项目主要基于物理化学和衍射物理，使用实验室技术和合成、x射线结构分析、光谱学、电子显微镜、元素分析和热分析，此外还在国家同步加速器和中子设施进行积极的研究。选定的矿物将在不同的P和T条件下就地检查。由此产生的信息将提供对矿物形成机制的深入了解，并提供对地球过程的定量理解。随着P和T的变化，矿物可能发生阳离子/阴离子有序-无序的变化。这些有序-无序过程可能对地球上声波的速度有重大影响。因此，在提出地球物理模型时需要考虑有序-无序效应。

Fundamental knowledge of the stability of minerals and the arrangement of atoms in their crystal structure as they exist deep in the Earth are important for providing realistic models for Earth processes. This research program attempts to answer the questions, why do solid materials have the properties that they exhibit? How do these properties change under different pressure and temperature (P and T) conditions? How does the ordering of atoms in a structure change in response to P and T? What are the effects of order-disorder on intrinsic properties? Physical, mechanical, thermodynamic, elastic, and chemical properties are governed by the arrangement of atoms in a solid on an atomic scale. Therefore, it is necessary to determine the atomic structures of materials, including minerals, using a multi-disciplinary approach and using various in situ experimental techniques to investigate the processes that govern their stabilities and properties under non-ambient (different P and T) conditions, including composition and time, and applying the results to Mineral Physics and Earth processes. The applicant is an established synchrotron radiation researcher who has used state-of-the-art experimental techniques at National Facilities in USA and France (APS, NSLS, and ESRF) and hopes to use or establish similar techniques at the Canadian Light Source (CLS) at Saskatoon. My research program is based heavily on physical chemistry and diffraction physics using laboratory techniques and synthesis, X-ray structure analyses, spectroscopy, electron microscopy, element analyses, and thermal analyses, in addition to active research at National Synchrotron and Neutron Facilities. Selected minerals will be examined in situ under different P and T conditions. The resulting information will provide insight into the mechanisms by which minerals are formed, and provide a quantitative understanding of Earth processes. With varying P and T, minerals may undergo changes in cation/anion order-disorder. These order-disorder processes may have significant effect on the velocities of sound waves in the Earth. Therefore, order-disorder effects need to be taken into account when geophysical models are proposed for the Earth.