X-ray imaging of melt, crystallization, and solid-solid phase transitions in the diamond anvil cell

Through collaboration between LLNL and the Extreme Condition Beamline at PETRA-III, new technical advancements have enabled time-resolved, simultaneous x-ray imaging and diffraction in the diamond anvil cell. Combined with in-situ diffraction, we present experimental results achieving ultra-fast propagation-based phase-contrast imaging of materials under variable pressure–temperature environments, including materials opaque to visible light, on millisecond to minute time-scales using both laser and resistive heating techniques. We utilize a combination of both static and dynamic diamond anvil cells to characterize the kinetics of high-pressure phase transitions, through direct visualization of solid-solid, solid-liquid, and liquid-solid transformations. This imaging technique allows us to visualize melting and crystallite growth, evolution of crystallite morphology, and observe nucleation sites during varying pressure and/or temperature conditions. Quantifying the pressure and temperature effects on crystallization mechanisms, nucleation and growth processes, and rates of transformations, will provide valuable kinetic parameters for our understanding phase transformations within materials under extreme conditions.