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 $V=10.5\mathrm{}\pm 0.2$ ${\mathrm{cm}}^3$/mol ($\frac{V}{V_{01}}=0.30\mathrm{}$), there is no evidence for band-gap closure.

• Received 29 December 1986

DOI:https://doi.org/10.1103/PhysRevLett.59.2670