Physics and Chemistry of Planetary Materials under Extreme Pressure and Temperature Conditions

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The objective of my research is to improve our abilities to understand the deep interior dynamics and evolution of Earth and other planets. The dynamics and evolution of Earth's and planetary interiors will influence the outermost features of the Earth and other planets. However, their interiors are inaccessible and cannot be directly investigated. Alternative approaches are to study Earth and planetary materials at simulated environments that are similar to Earth and planetary interiors. Importantly, behavior of materials at ambient conditions (1 atm and 25 C) is different from what they exhibit at greater depths. Therefore, only those data collected at pressure (P) and temperature (T) conditions corresponding to the certain depths are valid for modeling the structure and dynamics of the Earth's and planetary interiors. Therefore, study of Earth and planetary materials at P-T conditions corresponding to their deep interiors provide a promising approach to understand the dynamics and evolution of Earth's and planetary interiors. ******My research program uses a diamond-anvil cell (DAC, able to generate P to 3,000,000 atm) together with resistive and laser heating methods (able to heat the sample to 300-4000 K), to study planetary materials under extreme P-T conditions. The extensive P-T ranges (1-3,000,000 atm and 300-4000 K) allow us to replicate the conditions found within the Earth and planetary interiors. Moreover, using a custom-built micro-Raman system and synchrotron X-ray spectroscopy, the spectroscopic properties of relevant materials are also examined. ******In this proposal, we synthesize the important deep mantle phases (e.g. N-bearing silicates and iron nitrides, spinels, Zr-bearing silicates and oxide) and characterize them using synchrotron x-ray diffraction, x-ray spectroscopy, Raman and Brillouin scattering to understand their structures and physical properties (e.g. density, volume, elasticity, strength, sound velocity). The synthesized samples when quenched to ambient conditions will be examined by electron probe microanalysis and scanning electron microscopy for understanding the partitioning of the elements and element distributions within the samples, the melting criteria of the iron nitrides, and the crystal structures of the nano-scale phases. Our goals are (1) to evaluate the budgets of the N inside the Earth and other planetary interiors which is important for future planet explorations, (2) to understand the causes and mechanism of seismic anomalies (e.g. ultralow velocity) in deep Earth, (3) to evaluate the chromite spinel polymorphs at high P-T conditions and its connection to the shocked meteorites, and (4) to study strength of popular planetary ice (CO2, N2, CH4, NH3) that can be applied to modeling the dynamics of the planetary interiors.******HQP will receive extensive training in high P-T mineral physics that will provide transferable skills to prepare them for employment in academic, government and private sectors.**