Observation of the solid-solid and liquid-solid phase transitions in Gallium (Ga) at the µs-timescale

The proposal aims to measure the metastability of fluid Ga and examine its crystallization mechanism by varying the compression rate over four orders of magnitude. At high compression rates, significant overcompression of the metastable fluid is expected, similar to the behavior of liquid Ga at ambient pressure, where it can be undercooled to very low temperatures due to a high nucleation barrier. The data will test a recently proposed scaling law for solidification onset under extreme undercooling. The resulting crystal structure from the metastable fluid will be compared with those in the equilibrium phase diagram. Additionally, the experiment will explore how the tendency to form large single crystals under slow compression changes with increased compression rates. This study will use a new platform at ID09, which includes a piezo-driven dynamic diamond anvil cell and microsecond time-resolved XRD measurements with a Jungfrau detector.