Crystal structure of I2 at ambient temperature and
pressureorthorhombic crystal (space group Cmca)
InsulatorMolecules are layered to a-axis and form crystal. B.
Albert, K. Schmit, Z. Anorg. Allg. Chem. 627, 809 (2001).diatomic
molecule ()
Measure by X-ray diffraction.moleculemonatomicmolecular
dissociation ()Crystal structure of iodine under pressure
The distribution of atomic distanceAtomic distance is
continuously distributed in mesophase.K. Takemura, K. Sato, H.
Fujihisa and M. Onoda, Nature 423, 971 (2003).
Previous work (Temperature dependence of electrical
resistance)Under pressure, iodine becomes metal and
superconductor.
Experiment for high pressure[Top View]Sample300 m50 m100 m
Experiment for low temperatureWe can measure electrical
resistance and X-ray diffraction at the same time under low
temperature and high pressure. Little vibration Gas-pressure
cable
Metallization in phase Metal !6 K100 K200 K300 KIntensity
(arb.units)
Pressure boundary of phase and phase We can see the peaks of
only phase from 10 GPa to 20 GPa .We can see the peaks of both of
phaseand phase at 28~29 GPa.XRD at room temperature
15 GPa20 GPaAt 15 GPa and 20 GPa, I2 is metal.Temperature
dependence of electrical resistanceMetallization in phase XRD at
each temperature
SummaryMetallization in phase and phase .Molecular crystal I2
become metal not because the structure transition.mesophase (Phase
)0Pressure [GPa]2825K. Shimizu et al., J. Phys. Soc. Jpn., 61, 3853
(1992).Crystal structuremolecular (phase )monatomic (phase )
(bct)Electrical conduction property
