The crystal structure of the high-pressure metallic state of iodine has been determined by x-ray diffraction technique ultilizing a diamond-anvil high-pressure cell combined with a position-sensitive proportional counter. Diffraction intensities measured at 206 kbar were very well interpreted by assuming the space group $D_{2h}^{18}$ which is the same as that at atmospheric pressure. With further increase in applied pressure, the structure will approach to a face-centered orthorhombic lattice formed by monoatomic iodine.

• Received 23 March 1978

DOI:https://doi.org/10.1103/PhysRevB.18.715