Pressure-induced phase transitions in high entropy oxide and metal hydrides in DAC at over 100 GPa conditions

In this presentation, several selected crystalline systems were in situ studied under high pressure using synchrotron x-ray diffraction (XRD) technique in diamond anvil cell (DAC). Research topics involve phase transitions, isostructural transition, pressure tune charge transfer and mixed valance modifications behaviors, and negative linear compression at over 100 GPa conditions. One high entropy oxide system was used to investigate the compositions dependence of the phase transition sequence upon compression, and the fast compression rate effect was also studied. For many metal hydrides with the predicted superconducting properties, the responding superconducting phases determination are still quite challenging. Several selected cases such as Ca-H, Hf-H, would be presented based on the recent XRD results and discussed the possible general trend.