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.
Geophysical Laboratory, Carnegie Institution of Washington, Washington, DC 20015, USA. alazicki@ciw.edu
A
A
Lazicki
A F
AF
Goncharov
V V
VV
Struzhkin
R E
RE
Cohen
Z
Z
Liu
E
E
Gregoryanz
C
C
Guillaume
H-K
HK
Mao
Russell J
RJ
Hemley