Pressure-Induced Structural Phase Transitions in Solid Xenon

Pressure-induced structural phase transitions have been observed in solid xenon by high-pressure x-ray diffraction methods up to 137 GPa (1.37 Mbar). The face-centered cubic structure is unstable above 14 GPa and transforms to an intermediate, close-packed phase. Above 75 GPa a further transition takes place to the hexagonal close-packed structure which remains stable to at least 137 GPa. At this pressure, where $V=10.5\ifmmode\pm\else\textpm\fi{}0.2$ ${\mathrm{cm}}^{3}$/mol ($\frac{V}{{V}_{01}}=0.30$), there is no evidence for band-gap closure.