Equation of State and Phase Boundary of Post-Perovskite

后钙钛矿的状态方程和相界

• 批准号: 0738655
• 负责人: Sang-Heon Shim
• 金额: $ 25.98万
• 依托单位: Massachusetts Institute of Technology
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-01-15 至 2010-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0738655&HistoricalAwards=false
• 关键词: Equation; State; Phase; Boundary; Post

Intellectual Merit. The discovery of the phase transition in Mg-silicate perovskite (Pv) to a new phase (post-perovskite, PPv) at lowermost mantle conditions has influenced the interpretation of seismic observations and the understanding of the dynamic role of this region of the Earth's interior. Because there are discrepancies between recent experiments and theoretical calculations regarding the PPv transition, new and more sophisticated experimental work is needed. The PI's recently conducted XRD measurements on (Fe0.1Mg0.9)SiO3-PPv to 136 GPa captured the complete transformation from Pv+PPv mixture to pure PPv at in situ high P-T, which enables reliable determination of the phase boundary. This work also makes possible an accurate determination of the equation of state (EOS) for PPv. Further work is proposed to for pure and Al-bearing Mg-PPv. Combined work on pure, Fe-bearing, and Al-bearing Mg-Pv, the proposed measurements will allow self-consistent evaluation of density and compressibility across the PPv transition - thereby defining phase relations for the lower mantle.Broader Impacts. A long term goal is to understand the structure and dynamics of the mantle using experimental approaches, and taking advantage of rapid developments in synchrotron XRD techniques to study important geophysical problems. The most significant educational activity of this proposal is to provide research opportunities in mineral physics to MIT undergraduate students who will participate in the proposed project during summer. This project will also support Ph.D. research of K. Catalli. The outcome of the proposed research will also be incorporated into courses at MIT, "Structure of Earth Materials", "Introduction to Mineral Physics", and "The Core-Mantle Boundary", for undergraduate and graduate students.

智力上的功绩。镁硅酸盐钙钛矿(PV)在最低地幔条件下向新相(后钙钛矿，PPV)相变的发现，影响了对地震观测的解释和对地球内部这一区域动力学作用的理解。由于最近关于PPV转变的实验和理论计算之间存在差异，因此需要新的和更复杂的实验工作。PI最近对(Fe0.1Mg0.9)SiO_3-PPV进行的X射线衍射测量捕捉到了在原位高P-T下从PV+PPV混合物到纯PPV的完全转变，这使得可靠地确定相界成为可能。这项工作也使得精确确定PPV的状态方程成为可能。对纯铝镁PPV的进一步研究工作进行了展望。结合纯、含铁和含铝的镁-PV的工作，建议的测量将允许在PPV转变过程中对密度和可压缩性进行自洽的评估-从而定义下地幔的相关系。一个长期目标是用实验方法了解地幔的结构和动力学，并利用同步加速器X射线衍射技术的快速发展来研究重要的地球物理问题。这项提案最重要的教育活动是为麻省理工学院本科生提供矿物物理方面的研究机会，这些本科生将在夏季参与提案的项目。该项目还将支持K.Catalli的博士研究。这项拟议的研究成果还将被纳入麻省理工学院本科生和研究生的课程--“地球材料的结构”、“矿物物理学概论”和“核心-地幔边界”。