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Electrical conduction property of solid iodine in the molecular phase

Electrical conduction property of solid iodine in the molecular phase. Shimizu Group Yu TANAKA. Contents. ・ Introduction - pressure effect - structure of molecular crystal I 2 - previous work ・ Experiment ・ Results and Discussions ・ Summary. covalent bond. pressurization.

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Electrical conduction property of solid iodine in the molecular phase

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  1. Electrical conduction property of solid iodine in the molecular phase Shimizu Group Yu TANAKA

  2. Contents ・Introduction - pressure effect - structure of molecular crystal I2 - previous work ・Experiment ・Results and Discussions ・Summary

  3. covalent bond pressurization pressurization Pressure effect ― diatomic molecular crystal ― Molecule Insulator molecular dissociation (分子解離) monatomic metal

  4. Crystal structure of I2 at ambient temperature and pressure orthorhombic crystal (space group ：Cmca) Insulator diatomic molecule (二原子分子) Molecules are layered to a-axis and form crystal. B. Albert, K. Schmit, Z. Anorg. Allg. Chem. 627, 809 (2001).

  5. mesophase (Phase Ⅴ) Crystal structure Molecular (phase Ⅰ) monatomic (Phase Ⅱ) (bct) 0 25 28 Pressure [GPa] pressurization pressurization Crystal structure of iodine under pressure Measure by X-ray diffraction. molecular dissociation (分子解離) molecule monatomic

  6. molecular Phase Ⅰ coordination number mesophase Phase Ⅴ monatomic Phase Ⅱ atomic distance (Å) The distribution of atomic distance Atomic distance is continuously distributed in mesophase. K. Takemura, K. Sato, H. Fujihisa and M. Onoda, Nature 423, 971 (2003).

  7. K. Shimizu, N. Tamitani, N. Takeshita, M, Ishizuka, K. Amaya and S Endo, J. Phys.Soc. Jpn. 61, 3853 (1992). N. Sakai, K. Takemura and K. Tsuji, J. Phys.Soc. Jpn. 51, 1811 (1982). Previous work (Temperature dependence of electrical resistance) Under pressure, iodine becomes metal and superconductor.

  8. Pressure phase diagram mesophase (Phase Ⅴ) monatomic (Phase Ⅱ) (fcc) Molecular (phase Ⅰ) Crystal structure superconductor Electrical conduction property metal insulator K. Shimizu et al., J. Phys. Soc. Jpn., 61, 3853 (1992). 0 25 28 Pressure [GPa] Not clear !

  9. [Side View] Pressure cellDiamond Anvil Cell (DAC) Setting Electrical resistance measurement 4 probe method Deposited Electrode Ti + Pt Sample Pressure determination ruby-fluorescence ● ElectrodePt Insulator Almina Gasket SUS310S Diamond Anvil Experiment for high pressure [Top View] 50 μm 100 μm 300 μm Sample

  10. Pulse tube refrigerator Imaging plate DAC X-ray Experiment for low temperature • Little vibration • Gas-pressure cable We can measure electrical resistance and X-ray diffraction at the same time under low temperature and high pressure.

  11. Phase Ⅴ In phase Ⅴ Metallization in phase Ⅴ Metal ! Intensity (arb.units) 6 K 100 K 200 K 300 K

  12. Phase Ⅰ Phase Ⅴ Pressure boundary of phase Ⅰ and phase Ⅴ XRD at room temperature We can see the peaks of only phase Ⅰ from 10 GPa to 20 GPa . We can see the peaks of both of phaseⅠand phaseⅤ at 28~29 GPa.

  13. Metallization in phase Ⅰ XRD at each temperature 15 GPa Temperature dependence of electrical resistance • At 15 GPa and 20 GPa, I2 is metal. 20 GPa

  14. Summary mesophase (Phase Ⅴ) molecular (phase Ⅰ) monatomic (phase Ⅱ)(bct) Crystal structure superconductor Electrical conduction property insulator metal K. Shimizu et al., J. Phys. Soc. Jpn., 61, 3853 (1992). 0 Pressure [GPa] 15 25 28 Metallization in phaseⅠ and phase Ⅴ. Molecular crystal I2 become metal not because the structure transition.

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