In Situ Raman Spectroscopy Study for Phase Diagrams of Mantle Minerals at High Pressure and Temperature

这个项目是在他的新实验室使用新开发的拉曼光谱和激光加热系统研究地幔矿物在原位高压和高温下的相变和热力学性质。近年来，重要的地幔矿物，如Mg2SiO4、MgSiO3和SiO2的相变和热力学性质的差异需要新的实验方法。作为该项目的一部分，将开发一种新系统，使拉曼散射能够直接在高压-高温下在金刚石砧细胞中进行测量。这使得在实验室中进行原位相位识别成为可能，而这仅在少数同步加速器设施中是可能的。新系统将用于解决传统方法中的一些问题。本课题的核心目标是利用新型激光加热和光谱联合技术，研究SiO2中钙钛矿-尖晶石和后尖晶石的转变，Mg2SiO4中尖晶石后的转变，MgSiO3钙钛矿的下地幔相变和热力学性质，以及CaSiO3钙钛矿的四方立方转变。提出的地幔矿物相变研究将影响我们对地幔地震结构和动力学的认识。本提案中计划的实验将使用麻省理工学院新开发的研究和培训基础设施进行。这个项目也将影响麻省理工学院本科生和研究生的研究训练。该项目的研究成果将成为博士论文的基础。本研究将为麻省理工学院的本科生提供实验地球物理学的研究机会，这对于吸引新一代的矿物物理学研究人员尤为重要。

This project is to study the phase transitions and thermodynamic properties of mantle minerals at in situ high pressure and temperature using a newly developed combined Raman spectroscopy and laser heating system at his new laboratory. Recent discrepancies in the phase transitions and thermodynamic properties of important mantle minerals, such as Mg2SiO4, MgSiO3, and SiO2, demand a new experimental approach. As part of this project, a new system will be developed to enable Raman scattering measurements directly at high pressure-temperature in a diamond-anvil cell. This makes in situ phase identification possible in laboratory, which has been only possible at few synchrotron facilities. The new system will be used to resolve some of the problems in conventional approaches. The central goal of the project is to study the coesite-stishovite and the post-stishovite transitions in SiO2, the post-spinel transition in Mg2SiO4, lower mantle phase transitions and thermodynamic properties of MgSiO3 perovskite, and tetragonal-cubic transition in CaSiO3 perovskite using the new combined spectroscopy and laser heating system. The proposed research on phase transitions in mantle minerals will impact our understanding of seismologic structures and dynamics of the mantle. The planned experiments in this proposal will be conducted using the newly developed infrastructure for research and training at MIT. This project will also impact research training for undergraduate and graduate students at MIT. The research results from this project will become a basis for a PhD thesis. The proposed research is expected to provide research opportunities in experimental geophysics to undergraduate students at MIT, which will be particularly important to attract a new generation of researchers for mineral physics community.