Structural solution of the complex phases of dense sodium

We have discovered that sodium melting curve exhibits a pronounced minimum at ∼118 gigapascals and 300 kelvin. We also have found seven crystalline phases of Na at around this minimum. Currently, the full structural information of only three out of seven phases (oP8, cI16 and tI19) is available. The remaining phases are incredibly complex, arguably among the most complicated structural configurations observed in the elements - tI50, aP90, oC120 and mP512. The complexity of the phase behavior above 100 gigapascals suggests extraordinary liquid and solid states of sodium at extreme conditions and has implications for other seemingly simple metals.
In the past decade there were several technological advances which reshaped the modern high-pressure experimental single crystal spectroscopy. Using the current detectors, significantly improved diamond anvil cells and powerful software we will solve the structures of the remaining complex phases and look for the new ones.