Determining the Structural Behaviour of Potassium at Unprecedented Compressions

Even at a modest pressure of 100 GPa we have seen 6-fold compression in potassium (K) and rubidium (Rb), and above 300 GPa we expect 10-fold compression to be achieved. Such extreme compression ratios result in significant atomic core-valence overlap causing fundamental distortions in the electron band structure and exotic phases. We propose to investigate these structures in K to 500 GPa using both conventional and toroidal diamond anvil cells. The unprecedented brightness of the new ID27 beamline makes this experiment possible for the first time.