Anomalous optical and electronic properties of dense sodium.
Synchrotron infrared spectroscopy on sodium shows a transition from a high reflectivity, nearly free-electron metal to a low-reflectivity, poor metal in an orthorhombic phase at 118 GPa. Optical spectra calculated within density functional theory (DFT) agree with the experimental measurements and predict a gap opening in the orthorhombic phase at compression beyond its stability field, a state that would be experimentally attainable by appropriate choice of pressure-temperature path. We show that a transition to an incommensurate phase at 125 GPa results in a partial recovery of good metallic character up to 180 GPa, demonstrating the strong relationship between structure and electronic properties in sodium.
Lazicki
A
A
Geophysical Laboratory, Carnegie Institution of Washington, Washington, DC 20015, USA. alazicki@ciw.edu
Goncharov
A F
AF
Struzhkin
V V
VV
Cohen
R E
RE
Liu
Z
Z
Gregoryanz
E
E
Guillaume
C
C
Mao
H-K
HK
Hemley
Russell J
RJ