Refractive Index of Lithium Fluoride Ramp Compressed to 800 GPa

LLE Review, Volume 126 59 Introduction The transition of an insulator to a metal (metallization) at high compression is generally the result of pressure-induced closure of the band gap.1–4 Lithium fluoride’s (LiF’s) largeband-gap and ionic crystalline structure produces its uniquely high ultraviolet transmissivity. Two rare-gas solids, He and Ne, have anomalously high metallization pressures because of the predicted intershell band overlap, which is unique among monatomic materials.5 LiF holds a rare position among binary compounds in that Li+ and F– are isoelectronic with He and Ne, respectively. Therefore, LiF is expected to have a uniquely high metallization pressure among large-band-gap solid insulators.