Equation of State and Phase Boundary of Post-Perovskite

智力优势。在镁硅酸盐钙钛矿（Pv）的相变的发现，一个新的阶段（后钙钛矿，PPv）在地幔最低条件下影响了地震观测的解释和地球内部的这一地区的动态作用的理解。由于最近的实验和关于PPv跃迁的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进行了136 GPa的XRD测量，捕获了在原位高P-T下从Pv+PPv混合物到纯PPv的完全转变，这使得能够可靠地确定相边界。这项工作也使得有可能准确地确定状态方程（EOS）的PPv。对纯Mg-PPv和含铝Mg-PPv的制备进行了进一步的研究。结合对纯的、含铁的和含铝的Mg-Pv的研究，建议的测量将允许在PPv过渡期间对密度和压缩性进行自洽评估-从而定义下地幔的相位关系。长期目标是利用实验方法了解地幔的结构和动力学，并利用同步加速器XRD技术的快速发展来研究重要的地球物理问题。本提案最重要的教育活动是为麻省理工学院的本科生提供矿物物理学的研究机会，他们将在夏季参加拟议的项目。该项目还将支持博士学位。研究K.卡塔利拟议的研究成果也将纳入麻省理工学院的课程，“地球材料结构”，“矿物物理学介绍”和“核幔边界”，为本科生和研究生。

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.