High Pressure study of Bromine

Shimizu LabM2　 Hayashi Yuma

Contents• Introduction Iodine• Motivation• Experiments• Summary• Next plan

Introduction

http://www.cqst.osaka-u.ac.jp

room –temperature superconductor?

High-Pressure Effectintroduction

Moleculepressurization pressurization

Monoatomic

molecular dissociation

Applying pressure means…

Electronic states change.

The atomic distance becomes closer.

・ Structural transition・ Insulator-Metal transition

　　 Structural phase transition of iodineintroduction

B. Albert, K. Schmit, Z. Anorg. Allg. Chem. 627, 809 (2001).

Y. Fujii, K. Hase, N. Hamaya, Y. Ohishi, A. Onodera, O. Shimomura, and K. Takemura, Phys. Rev. Lett. 58, 796 (1987).

K. Takemura et al., Nature 423, 971 (2003).

Molecular dissociation@21GPa_non-hydrostatic pressure

Molecular phase ( )Ⅰ

Monoatomic phaseR.T.

Ⅱ Ⅲ Ⅳ

Pressure(GPa)240 25 43 55

Ⅴ

hydrostatic pressure

Ⅴ phase between and phase Ⅰ Ⅱat 24-25 GPa

K. Takemura et al., Nature 423, 971 (2003).

・ incommensurate structure

・ metal

introduction

Crystal structure Molecular phase ( )Ⅰ

Monoatomic phaseR.T.

Ⅱ Ⅲ ⅣⅤ

Iodine

Electrical property of Iodine in high pressure

N. Sakai, K. Takemura and K. Tsuji, J. Phys.Soc. Jpn. 51, 1811 (1982).

0 10 20 30 40 500.0

0.5

1.0

1.5

2.0

R/R

50K

T (K)

12 GPa

13 GPa

14 GPa

16 GPa

18 GPa

iodine

The temperature dependence of electrical resistance of iodine becomes positive at 14-16 GPa, indicating insulator to metal transition

introduction

Superconductivity of iodine

K. Shimizu et al., J. Phys. Soc. Jpn., 61, 3853 (1992).

Iodine becomes superconductor in phase at about 1.2 K.Ⅱ

introduction

Phase diagram of iodine

Crystal structure Molecular phase ( )Ⅰ

Monatomic phase

0

Pressure [GPa]

21

Insulator metal

Superconductor

16

R.T.

Electrical

characteristic

43 55

Ⅱ Ⅲ Ⅳ

Molecular　 dissociation

introduction

・ Iodine becomes superconductor in phase at about 1.2 K.Ⅱ

Ⅴ

Introduction

http://www.cqst.osaka-u.ac.jp

room –temperature superconductor?

High-Pressure Effectintroduction

Moleculepressurization pressurization

Monoatomic

molecular dissociation

Applying pressure means…

Electronic states change.

The atomic distance becomes closer.

・ Structural transition・ Insulator-Metal transition

　　 Structural phase transition of iodineintroduction

B. Albert, K. Schmit, Z. Anorg. Allg. Chem. 627, 809 (2001).

Y. Fujii, K. Hase, N. Hamaya, Y. Ohishi, A. Onodera, O. Shimomura, and K. Takemura, Phys. Rev. Lett. 58, 796 (1987).

K. Takemura et al., Nature 423, 971 (2003).

Molecular dissociation@21GPa_non-hydrostatic pressure

Molecular phase ( )Ⅰ

Monoatomic phaseR.T.

Ⅱ Ⅲ Ⅳ

Pressure(GPa)240 25 43 55

Ⅴ

hydrostatic pressure

Ⅴ phase between and phase Ⅰ Ⅱat 24-25 GPa

K. Takemura et al., Nature 423, 971 (2003).

・ incommensurate structure

・ metal

introduction

Crystal structure Molecular phase ( )Ⅰ

Monoatomic phaseR.T.

Ⅱ Ⅲ ⅣⅤ

Iodine

Electrical property of Iodine in high pressure

N. Sakai, K. Takemura and K. Tsuji, J. Phys.Soc. Jpn. 51, 1811 (1982).

0 10 20 30 40 500.0

0.5

1.0

1.5

2.0

R/R

50K

T (K)

12 GPa

13 GPa

14 GPa

16 GPa

18 GPa

iodine

The temperature dependence of electrical resistance of iodine becomes positive at 14-16 GPa, indicating insulator to metal transition

introduction

Superconductivity of iodine

K. Shimizu et al., J. Phys. Soc. Jpn., 61, 3853 (1992).

Iodine becomes superconductor in phase at about 1.2 K.Ⅱ

introduction

Phase diagram of iodine

Crystal structure Molecular phase ( )Ⅰ

Monatomic phase

0

Pressure [GPa]

21

Insulator metal

Superconductor

16

R.T.

Electrical

characteristic

43 55

Ⅱ Ⅲ Ⅳ

Molecular　 dissociation

introduction

・ Iodine becomes superconductor in phase at about 1.2 K.Ⅱ

Ⅴ

Motivation

Clarifying the mechanism of the pressure-induced metallization in halogen elements and molecular crystals.

Perform investigation of the crystal structure and electrical property of bromine under pressure.

Experiments

DiamondBr

Re

Setting Pressure-generating apparatus: DAC

Culet: 75 μm

Sample: Br (purity: 99.99%)

Gasket: ReThe processes of loading the sample in a DAC were performed in a nitrogen gas atmosphere and at liquid nitrogen temperature.

X-ray

Diffraction rayPerformed X-ray diffraction experiment @SPring-8

　　 Structure of Bromine under pressure

5 10 15 20 25

III + IV206 GPa

?

experiments

experiments

　　 Comparisons with calculations

-0.2

H (

mR

y/at

om)

0.2

0

0.6

50 60 70 80 90 100P (GPa)

Phase I(molecular)

Phase II(monatomic)

Enthalpy vs. Pressure

0.4

Phase V(modulated)

G = E + PV – TST → 0

H = E + PV

Phase V of bromine exists at 55-90 GPa in calculation.

Clarify the reasons of differences between experiments and calculations.

Experiments

Calculations

Electrical property of bromine 1

-2 20E (eV)

-2 20E (eV)

0E (eV)

10-10-20

0E (eV)

10-10-20

40 GPa

50 GPa

Electronic DOS

By calculation,we predict bromine has insulator-metal transition at 40-50 GPa in phase .Ⅰ

Electrical property of bromine 2

K Amaya et al 1998 J. Phys.: Condens. Matter 10 11179

Above 90GPa, small drops in electrical resistance are observed, which show the onset of superconductivity.

Summary

・ Under high pressure, bromine has the same structure changes as iodine　 without transition pressures.

・ It is predicted bromine has insulator-metal transition at 40-50 GPa by calculations, and at pressure higher than 90GPa, small drops in　electrical resistance are observed, which show the onset of superconductivity.

Next plan

Clarifying the mechanism of the pressure-induced metallization in bromine.

Careful investigation of the crystal structure and electrical property of Bromine in the phase I ,and comparisons of experiments with calculations.

How to estimate pressure

Ruby produces fluorescence when irradiated by laser. The wavelength of the peak changes with pressure.

For P < 100 GPa : Ruby Fluorescence（ルビー蛍光法）

For P > 100 GPa : Raman Spectroscopy ( ラマン分光法）

　　 P = 66.9 - 0.5281ν + 3.585×10-4 ν2

Irradiate diamond with laser. On applying pressure, the vibration of C-C bond in diamond changes, the

wavelength of scattered light becomes small.

Hall Effect of Iodine

・ The carrier of iodine is ‘hole’.

[top view]

I- I+

V- V+

V0

B

introduction

T. Yamauchi et al., J. Phys. Soc. Jpn., 63, 3207-3209 (1994).

RH ＝

（ n ： carrier density ）

Tc∝θDexp[-1/N(0)V ]

introduction

Structural phase transition of bromineMolecular dissociation near 80 GPa

Y. Fujii et al.,Phys. Rev. Lett. 63, 536(1989)

Electrical property of bromine

K Amaya et al 1998 J. Phys.: Condens. Matter 10 11179

Above 90GPa, small drops in electrical resistance are observed, which show the onset of superconductivity.

　　 Structure of Bromine under pressureexperiments

8040 50 60 70P (GPa)

2.5

3.0

Dis

tanc

e (Å

) New structural phase transition at about 65 GPa ?