Brillouin Scattering With Simultaneous X-Ray Diffraction at GSECARS, Advanced Photon Source: Toward Determination of Absolute Pressure Scales

Jay Bass1

Stanislav Sinogeikin1,2

Dmitry Lakshtanov1

Carmen Sanchez-Valle1

Vitali Prakapenka2,

Guoyin Shen2,3

Jean-Philippe Perrillat1

Jingyun Wang1

Bin Chen1

1 University of Illinois at UC, Geology Dept. 2 GSECARS, The University of Chicago3 HPCAT, Advanced Photon Sourse, Argonne National Laboratory4 Carnegie Institution of Washington, Geophysical Laboratory

Fall AGU 2006

Isothermal bulk modulus (volume measurements)

Adiabatic elastic moduli(velocity measurements)

P K (V )

VVo

V dV

K VdP

dV

2

SV

K VP2 (4 /3)VP

2

Brillouin Scattering with synchrotron X-rays at the APS

Elasticity Grand ChallengeCOMPRES Infrastructure Development Project

Measure sound velocities and density simultaneously

“Absolute” or internally consistent Pressure ScalesZha et al., Brillouin on MgO (PNAS, 2000)

Phase Transitions: Stishovite - CaCl2

Stishovite - CaCl2 : Brillouin scattering velocities

Brillouin scattering Acoustic waves present in a solid due to thermal motion of atoms

Laser light interacts with phonons (or density / refractive index fluctuations) and is scattered with Doppler shifted frequency

Brillouin shift is proportional to acoustic velocity

Vi = / 2n*sin (/2)

Laser

O rig inalfrequency

Severa lfrequencies

Analyser

Frequency

O rig ina lB rillou insh ifted,Vp or Vs

Laserbeam IN

Scattered Light OUT

q

Vi = / 2sin (*/2)

Platelet (symmetric) geometry

Schematic diagram of the Brillouin system installed at sector 13-BMD (GSECARS) at APS

Sinogeikin et al.,Rev.Sci. Instr. 77, 2006

Schematic diagram of the Brillouin system installed at sector 13-BMD at APS (Lower Tier)

Motorized translation components (controllable from outside the hatch, blue boxes): HMTS - horizontal motorized translation stage; VMTS - vertical motorized translation stage; MLFA - motorized laser focusing assembly; MSCA - motorized signal collecting assembly; SPOA - sample positioning and orientation assembly; SL-LB - sample light / light block.

Observation / feedback elements (red boxes): VC - video camera; BT - beam target.X-ray components: MAR - MAR Imaging plate; XBS - X-ray beam stop; CS - cleanup slit.

Mobile focusing/collecting part of the Brillouin system at 13-BMD GSECARS

X-ray image and integrated spectrum of single-crystal NaCl at ambient conditions

Single crystal NaCl (B1) at ~30 GPa in DAC in Ne pressure medium

Au+Pt+NaCl

NaClSinglecrystal

Ruby

100 μm Au+Pt+NaCl

Schematic view of simultaneous Brillouin scattering and X-ray diffraction in DAC

X-ray image and spectrum of single-crystal NaCl in Ne at 30 GPa

NaCl (B1)(200)

Ne

Single crystal Brillouin spectrum of NaCl (B1) and velocity distribution in (100) plane at 30.5 GPa

-15 -10 -5 0 5 10 15Velocity, km /s

Inte

nsity

N aC l, 30.5 G Pa[110] d irection

D iam ondV S

D iam ondV S

NaClVP

NaClVP

NaClVS

NaClVS

N eBS

0 30 60 90 120 150 180

0.0

2.0

4.0

6.0

8.0

10.0

Vel

ocity

, km

/s[100]

C 11= 313.1 (2 .0) G PaC 44= 9.1 (1 .0) G paC 12= 64.5 (1 .5) G Pa

NaCl (B1), 30.5 GPa

[110]

2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.4

D ensity

0

50

100

150

200

250

300

350

Cij's

, GP

a

C 11

C 12

C 44

2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.4D ensity

0

50

100

150

Isot

ropi

c m

odul

i, G

Pa

K S

H SH S+

H S-

K S=(C 11+2C 12)/3H ashin-Shtrikm an bounds

Single crystal and aggregate elastic moduli of NaCl (B1) as a function of density

0 10 20 30Pressure, G Pa

-0.8

-0.6

-0.4

-0.2

0.0

0.2

0.4

Ani

sotr

opy

fact

or

M gO

N aC l (B1)

A=(2C44+C12)/C11-1

Anisotropy of NaCl (B1) to 30 GPa

0.0

2.0

4.0

6.0

8.0

10.0

Vel

ocity

, km

/sVs [100]

Vs [110]

Vp [110]

0 10 20 30Pressure

Vp [100]

2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.4D ensity

2

3

3

4

4

5

Vs,

km

/s

H ashin-Shtrikm anVoigt-R euss-H ill

V S

2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.4D ensity

4

5

6

7

8

Vp,

km

/s

H ashin-Shtrikm anVoigt-R euss-H ill

V P

Aggregate velocities of NaCl (B1) as a function of density

“Absolute” equations of state / pressure scale

Isothermal bulk modulus (volume measurements)

Adiabatic elastic moduli (velocity measurements)

dVV

VKP

V

Vo

T)(

TT dV

dPVK

3/)2( 1211 CCKS

2SV

22 )3/4( PPS VVK

)1( TKK TS

We measure Ks as a function of volume directly. The problem is to convert KS to

KT at high pressure, e.g. we need to know volume dependence of and .Possible models/assumptions:

constK T

V

V

00

?1;0

0

q

V

Vq

Conclusions

We simultaneously measured single crystal (and aggregate) elastic moduli of NaCl (B1) with Brillouin spectroscopy and density with angle dispersive X-ray diffraction to 30.5 GPa.

At high pressure NaCl exhibits extreme elastic anisotropy, which is >3 times higher than that at ambient conditions.

Above ~17 GPa on approaching B1-B2 phase transition NaCl exhibits acoustic mode softening.

Above ~17 GPa the density – velocity relations deviate from linearity and violate Birch’s law.

Acoustic softening indicates that B1-B2 phase transition in NaCl may be multi-step and of more complicated nature than it was previously thought.

Pressure calculated from measured bulk modulus and density is higher than that calculated from Decker EOS by ~ 3-5% at 30 GPa.

Acknowledgments• NSF: Elasticity Grand Challenge

• COMPRES: Infrastructure development project

• GSECARS: Sector 13, Advanced Photon Source