Synchrotron high-pressure high/low temperature techniques ID27 team: J.P. Perrillat, G. Garbarino, W. Crichton, P. Bouvier, S. Bauchau
Jan 05, 2016
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