Synchrotron high-pressure high/low temperature techniques

Synchrotron high-pressure high/low temperature techniques

ID27 team: J.P. Perrillat, G. Garbarino, W. Crichton, P. Bouvier, S. Bauchau

Outline

Introduction – XRD Beamlines -

Research examples AND Limitations

Conclusion

Near RP,RT 3.5 MbarT<6000 K

Biology Geophysics

HP synchrotron beamlines are multidisciplinary instruments

ID27: Fully dedicated to HP XRD experimentsIn operation since 2006 in replacement of ID30

DetectorsSample environment

Mirrors MonochromatorX-raySource

ESRF6 GeV

Beamline ID27-ESRF

Diamond anvil cell• Pressures up to 3 Mbar • High temperatures Resistive heating up to 1000 K Laser heating T>4000 K • Low temperature down to 5 K (Helium cryostat)Main X-ray techniques• X-Ray single X-tal and powder diffraction in monochromatic mode

The Paris-Edinburgh large volume cell:

The only monochromatic LVC

• Pressure up to 17 GPa on 5 mm3 sample

volume

• Resistive heating up to 2300 K

Main X-ray technique: X-ray diffraction on powders/liquids/amorphous materials

Structure determination at very HP (P>1.2 Mbar) requires a very intense and very small X-ray beam.

ID30

One remark:

2 m

--

12 m

--

ID30ID27

Very intense micro-focused beam (2 microns) using two KB multi-layer mirrors at short wavelengths: 0.15<<0.4 Å

Kirkpatrick-Baez focusing mirrors

35 µ

m

P gauge (ruby ball)

Micro-grains of iron and tungsten in helium pressure Medium

High precision at ultra-high pressures: case of iron

Interest:

Geophysics: Main constituent of Earth’s core Physics: Magnetism

High precision at ultra-high pressures: case of iron

Fe

WFe

W

2

Ref: A. Dewaele, P. Loubeyre, F. Occelli, M. Mezouar, Phys. Rev. Lett. 97, 215504 (2006)

Fe + W in He at 199 GPa

11

10

9

8

7

V(Å

3/a

t)

200150100500P (GPa)

Fe -

Fe -

Our data (4 experiments)

Mao et al., 1990

Diamondbreakage

Max. P at ID30

Limitation: The diamond anvil cell not the X-ray beam!

5 micron singlecrystal of oxygen ina 20 micron gaskethole (helium pressuremedium)

Structure of metallic oxygen?

(insulator) (metal) transition at P~100 GPa

ID30

O2

G. Weck,S. Desgreniers,P. Loubeyre, M. MezouarID30, 139 GPa

Poor data quality,high background from the DAC

G. Weck,S. Desgreniers,P. Loubeyre, M. MezouarID27, 139 GPa

ID27

Data of much higher quality/ID30

BUT not enough to solve the structure…

transition degrades the singleX-tal quality (large rocking curves >1)

Structure of metallic oxygen?

+ Raman

C2/c allows only 6 active Raman modes phase has the C2/m symmetry

More single X-tal data of the phase(different orientations)

Two possible monoclinic space groups: C2/c and C2/m

G. Weck,S. Desgreniers,P. Loubeyre, M. Mezouar, PRL, in press

Limitation:

Single crystal quality! (not the X-ray beam)

Solution:

(In situ) HP/HT single X-tal growth

P-T Phase diagram of sodium

It is possible to grow a single x-tal of Na at ~120 GPa near RTand perform a full structural determination.

Ref: Gregoryanz E, Degtyareva O, Somayazulu M, Hemley RJ, Mao HK, PRL, 94,185502 (2005)

Ref: E. Gregoryanz, L. Lundegaard, M.I. McMahon,C. Guillaume, R.J. Nelmes, M.Mezouar, Science, 320,1054 (2008)

Examples of high quality single x-tal diffraction patterns of Na collected at ID27

Beamsize~ 3m; =0.3738 ÅSample volume~ 10x10x5 m3

Phase diagram around the melting curve minimum at P=117 GPaMany new and unpredicted structures of very high complexity

At atmospheric conditions

Hydrogen is a fundamental element for biology, chemistry and physics

At high pressure

Hydrogen is of high interest for physics and geophysics -Principal constituent of giant planets such as Jupiter (90%)

-Prediction of the existence of a metallic form of hydrogen by Eugene Wigner in 1935

Hydrogen at high very high pressure

Ref. : R. Hemley, M. Hanfland, et al. (Geophysical Lab., Washington)

100 120 140 160 180 2000

50

100

150

200

250

H2

Phase III

Phase II

Phase I

Te

mp

éra

ture

(K

)

Pression (GPa)50 100 150 200

0

50

100

150

200

250

300

D2

Phase III

Phase II

Phase I

Te

mp

érat

ure

(K

)

Pression (GPa)

Phase diagrams of H2 and D2 from spectroscopic measurements up to 200 GPa (1994)

3 phases identified but no structural determination of phase II and III.Phase I hcp lattice of freely-rotating molecules Phase II and III ??

Equation of state of hydrogen I up to 120 GPa at ESRF ID09 (1996)BUT using the EDX technique no structural determination

Single crystal of H2 in helium pressure medium

Ref.: P. Loubeyre et al., Nature, 383, 702 (1996)

For almost 10 years , all attempts to solve the structure of phase II failedToo many experimental difficultiesHigh pressure - Low Z material - Extremely reactive –Hydrogen is certainly the most difficult sample to study with X-rays at very HP.

100 120 140 160 180 2000

50

100

150

200

250

H2

Phase III

Phase II

Phase I

Tem

péra

ture

(K

)

Pression (GPa)

Structure solved in 2005 by a combination of mononochromatic XRDfrom ID30/ID09 and neutron data from LLB (Igor Goncharenko)

Phase II has an hcp incommensurate structure with a local orientational order (Pa3 local symmetry).

More details in:

100 120 140 160 180 2000

50

100

150

200

250

H2

Phase III

Phase II

Phase I

Te

mp

éra

ture

(K

)

Pression (GPa)

ID30

Phase III of hydrogen not reachable at ID30 because of the too large beam size

ID27

10 µm single crystal of H2 in helium pressure mediumP>150 GPa

Very weak diffraction peak of H2 at P=150 GPa

100

Limitations:Control of crystal orientations

Compton scattering from diamonds

20 40 60 80 100 120 140 160 180 2001,50

1,55

1,60

1,65

1,70

1,75

1,80

1,85

1,90

Phase I Phase III

a

10

0 (

A)

P(GPa)

Phase II

Solid H2 at 40 K

Only result so far:Evolution of the 100 d-spacing of hydrogen up to phase III

Structure of phase III is still an open question…

Experimental method - Double-sided laser heating system at ID27

Dedicated experimental hutch – The system is mounted on a highstability 5 tons marble

Double-sided laser heating system at ID27

Accessible PT domain for in situ powder XRD: P>2 Mbar; T>4000 K

Laser beamX-ray beamSample Imaging and T measurement

 The accurate determination of melting curves is of fundamental interest in different research areas such as physics and geophysics.

• 2 classical experimental methods

-Optical measurements in the laser heated diamond anvil cell

-Melting induced by shock compression

• Ab-initio calculations

Large temperature discrepancies between these 3 methods T>1500 K at 2 megabar for iron.

Melting at HP

Lead is a good candidate for melting studies using XRD : good YAG laser absorber high Z material melting curve determined by optical DAC technique, shock compression and calculated using ab-initio methods in a wide pressure domain

4000

3500

3000

2500

2000

1500

1000

T(K

)

806040200P(GPa)

This study (DAC) Godwal et al., 1990 (DAC) Partouche et al. 2005 (shock) Cricchio et al. (MD)

Pb

Theory (Cricchio et al. MD)

----

Large discrepancy in melting temperaturesT>1000 K at P=80 GPa

Melting curve of lead

New approach developed at beamline ID27 :Fast in situ X-ray diffraction in the double-sided laser heated diamond anvil cell.

Advantages:

It is sensitive to the bulk of the sample (#surface) The XRD measurements are performed at thermodynamic equilibrium (#shock) It uses well established pyrometric methods

Also important:

X-ray diffraction in the laser heated DAC provides an unambiguous signature of the melt at thermodynamic equilibrium and identifies chemical reactions if any.

Laser beam

X-ray beam

Double sided laser heating of iron in argon at 1.2 Mbar in a 60 m gasket holeCollaboration: R. Boehler, MPI MainzD. Errandonea, Univ. of Valencia

The sample is heated on both sides by 2 focused YAG laser providing a maximum power of 80 Watts.

The 2 lasers are slightly defocused in order to create a large and homogenous heated area of about 30 microns. The temperature is measured at the center of the hot spot by analyzing the pyrometric signal emitted by a 2x2 µm2 area

The X-ray beam is highly focused on a 3x3 µm2 area which is 10 times smaller than the heated area

The X-ray beam is perfectly aligned at the center of the laser hot spot (within 1 µm precision) by a direct visualization of the fluorescence signal created by the X-ray beam on a CCD camera

Experimental method

The temperature is gradually increased by tuning the laser power

For each increment of the laser power, the temperature is measured by pyrometry and a diffraction pattern is automatically collected

-The temperature increment is ~30 K-The typical cycle time is ~2 seconds

The pressure is measured in situ using NaCl as pressure marker

More than 5000 XRD patterns have been collected!

Experimental method

P=61 GPa

Experimental method

Melting at P=61 GPaNaCl pressure medium

E=33 keVFocused X-ray beam of 3x3 m2

Mar CCD detector1 frame/2 sec.

Melting curve in good agreement with theorybut in contradiction with previous experimental data (Shock, or opticallyin DAC)

Ref: A. Dewaele, M. Mezouar, N. Guignot, P. Loubeyre, Phys. Rev. B 76, 144106 (2007)

Limitations:

Detector: commercial CCD detectors are too slow for sub-second time resolved experiments.the photon flux is not the problem

Sample containers: major problems in laser heated DACs liquid confinement and chemical reactions

Possible solution: optimized containers:

Ref.: R. Benedetti et al., Appl. Phys. Lett., 92, 141903 (2008)

Al2O3O2

Au

Conclusion:

HP Beamlines with outstanding performance in terms of photon flux and focusing capabilities are in operation

Limitations are mostly coming from “external” factors:

Max. P: Limited by the DACBackground from the DAC for light elements studiesSample preparation: single X-tal growth at megabar pressures,

Solutions:

Use of complementary techniques: Neutrons (for low P), Raman, Brillouin,IXS,…micro-assemblies for laser heated DAC

Improved sample environment laboratories on site: HPSynch at APS,PECS (partnership for science at extreme conditions) at the ESRF