Sodium X-Ray Diffraction in the High-Pressure Regime

X. GongUniversity of RochesterLaboratory for Laser Energetics

59th Annual Meeting of the American Physical SocietyDivision of Plasma Physics

Milwaukee, WI 23–27 October 2017

1

200

400

600

8001000

2000

Tem

per

atu

re (

K)

20 40 60 80 100 200Pressure (GPa)

Liquid

Solid

bcc

Solid

fcc

Solid

cI16

tI19

mP512

oC120tI50

Isentrope

Melting curve

LiquidSolid

aP90

oP8oP8cI16

aP90

hP4

TC13838

A solid hP4 phase of sodium has been observed at ~320 GPa

• Na has been previously observed to transform into an optically transparent phase at 200 GPa*

• The phase is predicted by simulation to be a structurally complex “electride” hP4 structure*

• Na was ramp compressed to ~320 GPa on the OMEGA EP Laser System and studied using in-situ x-ray diffraction

• The existence of the hP4 phase at ~320 GPa indicates that the rise of the melting temperature starting at 120 GPa continues even at higher pressures

2

Summary

* M. Marqués et al., Phys. Rev. B 83, 184106 (2011).

Collaborators

D. N. Polsin, J. R. Rygg, T. R. Boehly, L. Crandall, B. J. Henderson, S. X. Hu, M. Huff, R. Saha, and G. W. Collins

University of Rochester Laboratory for Laser Energetics

R. Smith, J. H. Eggert, and A. E. Lazicki

Lawrence Livermore National Laboratory

M. McMahon

Department of Physics, University of Edinburgh

3

TC13839

At high pressures, Na has a unique melting curve* that possessesa minimum at 120 GPa, then rises steeply

4

200

400

600

8001000

2000

Tem

per

atu

re (

K)

20 40 60 80 100 200Pressure (GPa)

Liquid

Solid

bcc

Solid

fcc

Solid

cI16

tI19

mP512

oC120tI50

Melting curve

aP90

oP8oP8cI16

aP90

*M. Marqués et al., Phys. Rev. B 83, 184106 (2011), and references therein.

TC13840

Diamond-anvil-cell (DAC) experiments* show that Na transformsinto an optically transparent phase at 200 GPa

5

* Y. Ma et al., Nature 458, 182 (2009).

200

400

600

8001000

2000

Tem

per

atu

re (

K)

20 40 60 80 100 200Pressure (GPa)

Liquid

Solid

bcc

Solid

fcc

Solid

cI16

tI19

mP512

oC120tI50

Melting curve

aP90

oP8oP8cI16

aP90

Reflecting

TC13841

Diamond-anvil-cell (DAC) experiments* show that Na transformsinto an optically transparent phase at 200 GPa

6

200

400

600

8001000

2000

Tem

per

atu

re (

K)

20 40 60 80 100 200Pressure (GPa)

Liquid

Solid

bcc

Solid

fcc

Solid

cI16

tI19

mP512

oC120tI50

Melting curve

aP90

oP8oP8cI16

aP90

AbsorbingReflecting

* Y. Ma et al., Nature 458, 182 (2009).

TC13842

Diamond-anvil-cell (DAC) experiments* show that Na transformsinto an optically transparent phase at 200 GPa

7

200

400

600

8001000

2000

Tem

per

atu

re (

K)

20 40 60 80 100 200Pressure (GPa)

Liquid

Solid

bcc

Solid

fcc

Solid

cI16

tI19

mP512

oC120tI50

Melting curve

aP90

oP8oP8cI16

aP90

AbsorbingReflecting Transparent

* Y. Ma et al., Nature 458, 182 (2009).

TC13843

This phase is predicted* to be an “electride” hP4 structure, where conduction electrons are “trapped” in interstitial wells, producing an insulator

8

* Y. Ma et al., Nature 458, 182 (2009).

hP4: a double-hexagonal close-packed (dhcp)structure squeezed along the c axis.

Electron localization function

Na1 Na2

Interstitial

IonElectron

Na2

Na1120°

a a

c c

a b

C

A

C

B

C

TC13844

The powder x-ray diffraction image-plate (PXRDIP)* diagnostic is usedto obtain diffraction data of a compressed powder Na sample

9

Laserdrive

Cu Hea, 1.48 Å

X-raysource

C Na C Tungsten pinholecollimator/reference

VISAR**

Image plates

* J. R. Rygg et al., Rev. Sci. Instrum. 83, 113904 (2012).**VISAR: velocity interferometer system for any reflector

TC13845

The powder x-ray diffraction image-plate (PXRDIP)* diagnostic is usedto obtain diffraction data of a compressed powder Na sample

10

Laserdrive

Cu Hea, 1.48 Å

C Na C

VISAR

Image plates

C Na C

W

W

Target structure

X ray

VISARLaserdrive

Tungsten pinholecollimator/reference

X-raysource

* J. R. Rygg et al., Rev. Sci. Instrum. 83, 113904 (2012).

TC13846

The powder x-ray diffraction image-plate (PXRDIP)* diagnostic is usedto obtain diffraction data of a compressed powder Na sample

11

Laserdrive

Cu Hea, 1.48 Å

X-raysource

C Na C Tungsten pinholecollimator/reference

VISAR

Image platesDelivered target drive and x-raysource drive the pulse shape

Time (ns)0 5 10 15 20 25

Po

wer

(T

W)

100

10–1

10–2

Target driveramp pulse

X-ray spectrometerdrive 1-ns pulse

* J. R. Rygg et al., Rev. Sci. Instrum. 83, 113904 (2012).

TC13847

The powder x-ray diffraction image-plate (PXRDIP)* diagnostic is usedto obtain diffraction data of a compressed powder Na sample

12

* J. R. Rygg et al., Rev. Sci. Instrum. 83, 113904 (2012).

Laserdrive

Cu Hea, 1.48 Å

X-raysource

C Na C Tungsten pinholecollimator/reference

VISAR

Image plates

Debye–Scherrer powder diffraction

Line x-ray sourceCompressed randomly

oriented crystalsd1

2θ2

2θ1

Debye–Scherrer

rings

2θ1

2θ2

Debye–Scherrer

ringsd1

Line x-ray sourceCompressed randomly

oriented crystals

TC13848

VISAR data are used to determine the velocity of the diamond free surface,which is back-propagated to determine the pressure in the Na sample

13

10 15 20 25 30 35

Time (ns)

12

10

8

6

4

2

0

–2

Vel

oci

ty (

km/s

)

VISAR raw dataFree surface

Diamond window free-surface velocity

VISAR

So

diu

m58

nm

Dia

mo

nd

win

do

w77

nm

Dia

mo

nd

ab

lato

r40

nm

340

320

300

280

260

240

220

Pre

ssu

re (

GP

a)

18 20 22 24 26

Time (ns)

TC13849

Raw diffraction data are scanned from image plates on five sides of the box and projected onto a {–2i plane

14

X-raysource

Image plates

VISAR

40 50 60 70 80 90

150

100

50

0

–50

–100

–150

( )°2i

()°

{

The four brightest lines are tungsten bcc* diffraction signals,which are used for calibration

TC13850

15

* bcc: body centered cubic

40 50 60 70 80 90

150

100

50

0

–50

–100

–150

Calibration lines

( )°2i

()°

{

40 45 50 55 60 65 70

W W W0.20

0.15

0.10

0.05

0.00

Inte

nsi

ty

2i (°)

TC13851

The three weaker lines are sodium diffraction lines,consistent with hP4 structure

16

40 50 60 70 80 90

150

100

50

0

–50

–100

–15043.3°

60.9°Sodium diffraction

lines

65.7°

( )°2i

()°

{

40 45 50 55 60 65 70

Na(011)

Na(012)

Na(110)

0.20

0.15

0.10

0.05

0.00

Inte

nsi

ty

2i (°)

TC13852

The three weaker lines are sodium diffraction lines,consistent with hP4 structure

17

40 50 60 70 80 90

150

100

50

0

–50

–100

–15043.3°

60.9°Sodium diffraction

lines

65.7°

( )°2i

()°

{

Na2

Na1120°

a a

c c

a b

C

A

C

B

C

a = 2.73 Åc = 3.72 Åc/a = 1.36t = 6.36 g/cm3

t/t0 = 6.57

Sodium has a solid phase at ~320 GPa, which is consistent with hP4 structure

TC13853

18

Na2

Na1120°

a a

c c

a b

C

A

C

B

C

hP4

200

400

600

8001000

2000

Tem

per

atu

re (

K)

20 40 60 80 100 200Pressure (GPa)

Liquid

Solid

bcc

Solid

fcc

Solid

cI16

tI19

mP512

oC120tI50

Isentrope

Melting curve

aP90

oP8oP8cI16

aP90

TC13854

The melting temperature rises at >120 GPa

19

Na2

Na1120°

a a

c c

a b

C

A

C

B

C200

400

600

8001000

2000

Tem

per

atu

re (

K)

20 40 60 80 100 200Pressure (GPa)

Liquid

Solid

bcc

Solid

fcc

Solid

cI16

tI19

mP512

oC120tI50

Isentrope

Melting curve

LiquidSolid

aP90

oP8oP8cI16

aP90

hP4

TC13838

A solid hP4 phase of sodium has been observed at ~320 GPa

20

Summary/Conclusions

• Na has been previously observed to transform into an optically transparent phase at 200 GPa*

• The phase is predicted by simulation to be a structurally complex “electride” hP4 structure*

• Na was ramp compressed to ~320 GPa on the OMEGA EP Laser System and studied using in-situ x-ray diffraction

• The existence of the hP4 phase at ~320 GPa indicates that the rise of the melting temperature starting at 120 GPa continues even at higher pressures

* M. Marqués et al., Phys. Rev. B 83, 184106 (2011).