Structural complexity in ramp-compressed sodium to 480 GPa

Danae N. Polsin*, Amy Lazicki, Xuchen Gong, Stephen J. Burns, Federica Coppari, Linda E. Hansen, Brian J. Henderson, Margaret F. Huff, Malcolm, I McMahon, Marius Millot, Reetam Paul, Raymond F. Smith, Jon H. Eggert, Gilbert W. Collins, J. Ryan Rygg

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The properties of all materials at one atmosphere of pressure are controlled by the configurations of their valence electrons. At extreme pressures, neighboring atoms approach so close that core-electron orbitals overlap, and theory predicts the emergence of unusual quantum behavior. We ramp-compress monovalent elemental sodium, a prototypical metal at ambient conditions, to nearly 500 GPa (5 million atmospheres). The 7-fold increase of density brings the interatomic distance to 1.74 Å well within the initial 2.03 Å of the Na+ ionic diameter, and squeezes the valence electrons into the interstitial voids suggesting the formation of an electride phase. The laser-driven compression results in pressure-driven melting and recrystallization in a billionth of a second. In situ x-ray diffraction reveals a series of unexpected phase transitions upon recrystallization, and optical reflectivity measurements show a precipitous decrease throughout the liquid and solid phases, where the liquid is predicted to have electronic localization. These data reveal the presence of a rich, temperature-driven polymorphism where core electron overlap is thought to stabilize the formation of peculiar electride states.
Original languageEnglish
Article number2534
Pages (from-to)1-7
Number of pages7
JournalNature Communications
Issue number1
Publication statusPublished - 9 May 2022


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