Structural Changes in Minerals and their Effect on Intrinsic Properties

我的长期研究计划考察了矿物的行为(物理、机械、热力学、弹性和化学性质)作为压力(P)、温度(T)、成分(X)和时间(T)的函数，即P-T-X-t条件，这是基于晶体中原子的排列。了解矿物的行为对于为地球过程提供现实的模型至关重要，因为矿物的性质受原子排列的支配。我的研究项目试图回答这样的问题：为什么固体材料具有它们所展示的成分、结构和性质？这些特性在不同的P和T条件下是如何变化的？结构中原子的有序如何随着P-T-X-t的响应而改变？有序无序对固有性质或内部性质有什么影响，例如密度？为了回答这些问题，有必要使用多学科方法来确定矿物的原子结构。我们使用各种现场实验技术来研究在环境和非环境(不同的P和T)条件下(包括X和t)控制矿物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。我的研究项目以物理化学和衍射物理为基础，使用实验室的实验技术，此外还在同步加速器和中子设施进行创新研究，我在那里是一名成熟的研究员。我们已经成功地在不同的P-T-X-t条件下表征了几个矿物群，在这里我们考察了石榴石群矿物。 我未来5年的短期目标是用P-T-X-t研究石榴石类矿物的行为。石榴石很重要，因为它们在一系列P-T-X-t条件下出现，并保存了有关火成岩和变质过程的重要记录。石榴石具有重要的技术特性(例如，激光和汽车电池)，其中一些形成了影响其特性的天然“薄膜”。“薄膜”以成分分带的形式出现，这在长石和大约75种其他矿物中是众所周知的，所以我们的工作将对许多矿物产生影响。石榴石中的带的化学和结构参数略有不同。石榴石固溶体中的阳离子取代和分带必须考虑它们的热力学行为，以及它们在地质测温、地质压力测量和地质年代学中的有效应用。此外，无序过程会影响地震速度，这是地球物理模型所必需的。我们将研究石榴石中的多相、异常双折射、分带、阳离子顺序、扩散和地震速度。这项工作将为至少14名新生提供出色的培训。他们将学习解决矿物学、结晶学和材料科学领域问题的重要技术。

My LONG-TERM RESEARCH PROGRAM examines mineral behaviour (physical, mechanical, thermodynamic, elastic, and chemical properties) as a function of pressure (P), temperature (T), composition (X), and time (t), that is, P-T-X-t conditions, which is based on the arrangement of atoms in the crystal. Understanding mineral behaviour is essential for providing realistic models for Earth processes because mineral properties are governed by the arrangement of atoms. My research program attempts to answer questions such as: why do solid materials have the composition, structure, and the properties that they exhibit? How do these properties change under different P and T conditions? How does the ordering of atoms in a structure change in response to P-T-X-t? What are the effects of order-disorder on intrinsic or internal properties, e.g., density? To answer these questions, it is necessary to determine the atomic structures of minerals using a multi-disciplinary approach. We use various in situ experimental techniques to investigate the processes that govern mineral stabilities and properties under ambient and non-ambient (different P and T) conditions, including X and t, and to apply the results to Mineral Physics and Earth processes. My research program is based on physical chemistry and diffraction physics using experimental techniques in laboratories in addition to performing innovative research at synchrotron and neutron facilities, where I am an established researcher. We have successfully characterized several mineral groups under varying P-T-X-t conditions and here we examine the garnet-group minerals. My SHORT-TERM OBJECTIVES FOR THE NEXT 5 YRS are to examine the behaviour of garnet-group minerals with P-T-X-t. Garnets are important because they occur over a range of P-T-X-t conditions and they preserve important records of igneous and metamorphic processes. Garnets have important technological properties (e.g., lasers and automotive batteries) and some form natural "thin films", which affect their properties. "Thin films" occur as compositional zoning, which is well known in feldspars and about 75 other minerals, so our work will have implications for numerous minerals. Zones in garnets have slightly different chemical and structural parameters. Cation substitution and zoning in garnet solid solutions must be considered in their thermodynamic behaviour and their effective use in geothermometry, geobarometry, and geochronology. Moreover, order-disorder processes affect seismic velocities and are needed for geophysical models. We will study multiple phases, anomalous birefringence, zoning, cation order, diffusion, and seismic velocities in garnets. This work will provide excellent training for at least 14 new students. They will learn important techniques to solve problems in the fields of mineralogy, crystallography, and materials science.