Seminar: Understanding thermodynamics of critical metal materials under extreme conditions

ABSTRACT

Critical metals, including rare earth elements (REE), U and Th, are in high demand due to their pervasive use in emerging technology and renewable energy applications. Understanding their thermodynamic parameters is crucial for predicting their transport, deposit, and alteration behaviors in relevant geological conditions (e.g., extreme conditions). In our group, we use a set of structural-thermodynamic techniques to in situ probe chemical and physical changes of critical metal materials under elevated pressure and/or temperature conditions. Specifically, high temperature calorimetry and in situ high temperature X-ray diffraction (XRD) were implemented to investigate phase transition and corresponding enthalpies of reaction and mixing. The high pressure structures and equation of states were studied by coupled diamond anvil cell with synchrotron for in situ high pressure XRD, along with density functional theory (DFT). The elastic constants can also be obtained by resonant ultrasonic spectroscopy. By combining these methods, we can obtain more comprehensive thermodynamic parameters for relevant REE mineral phases. In this talk, I will discuss our recent finding on the high pressure structures of zircon, xenotime-type minerals (commonly accommondating REE and actinides), high temperature transitions of REE phosphates, and thermodynamic of mixing of REE phosphate and carbonate mineral phases.

BIOGRAPHY

Xiaofeng Guo is an associate professor of the Department of Chemistry at Washington State University. His research has focused primarily on thermodynamics and structures of nuclear materials, fuel materials for next generation reactor concepts, nuclear waste forms, and lanthanide- and actinide-containing minerals, under combined extreme conditions (high pressure and temperature). He has expertise in neutron and synchrotron X-ray based scattering and absorption spectroscopies, and their applications in in situ high-pressure and high-temperature studies. He also has expertise in synchrotron X-ray based scattering and absorption spectroscopies, and their applications in in situ high-pressure and high-temperature studies. Guo received his Ph.D. in Chemistry from the University of California, Davis in 2014. He was a G. T. Seaborg postdoctoral fellow at Los Alamos National Laboratory from 2015 to 2017. He is a recipient of the NSF CAREER Award in 2022.