Incommensurately Modulated Phase of Iodine Under High Pressure.

High-pressure powder x-ray diffraction experiments have been carried out on iodine at room temperature with a helium-pressure medium. A new high-pressure phase has been found in the pressure range 24–28 GPa, in the close vicinity of the molecular dissociation. The structure is incommensurately modulated, which we interpret as a transient state between molecular and monatomic ones. [ABSTRACT FROM AUTHOR]