Nature of the transformation in liquid iodine at 4 GPa

作者：Wakabayashi Daisuke^*; Funamori Nobumasa; Kikegawa Takumi; Watanabe Kazuki; Kohara Shinji; Nitani Hiroaki; Niwa Yasuhiro; Takeichi Yasuo; Abe Hitoshi; Kimura Masao

来源：PHYSICAL REVIEW B, 2017, 96(2): 024105.

DOI：10.1103/PhysRevB.96.024105

To clarify the nature of the transformation in liquid iodine, which is reported to occur at around 4 GPa, we have conducted x-ray absorption fine structure (XAFS) and x-ray diffraction (XRD) measurements up to 9 GPa. In the XAFS spectra, the oscillation attributable to the molecular bond persisted to 9 GPa but showed a significant decay above 4-5 GPa. Similarly, in the pair-distribution function obtained from XRD profiles, the peak assigned to the molecular bond persisted to 9 GPa but showed a significant broadening above 4-5 GPa. While the volume contracts significantly (more than 30%), the molecular bond expands by about 5% with increasing pressure between 1 and 9 GPa. Detailed analyses, with the aid of Reverse Monte Carlo modeling techniques, clarify that the transformation may be characterized by the onset (or drastic increase in the probability) of rebonding among adjacent molecules and the change in electronic state (possibly metallization) without molecular dissociation.

• 出版日期2017-7-17