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

Massachusetts Institute Of Technology, Cambridge MA

Investigators

Abstract

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.