quasicrystals structureanddynamics...nature materials 6 (2007) 977-984....
TRANSCRIPT
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Quasicrystals Structure and dynamics
M. de Boissieu
SIMaP, Grenoble-‐INP, CNRS, UJF St Mar=n d’Hères France.
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Quasicrystals
Long range order with ‘Forbidden’ 5-‐fold symmetry No periodicity QUASICRYSTAL: A NEW KIND OF LONG RANGE ORDER The noDon of crystal is redefined
From A.P. Tsai and H Takakura
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Stable Quasicrystals are observed in many different systems and can be grown as large single grains
Intermetallic alloys: AlLiCu, AlCuFe, AlPdMn, ZnMgY, CdYb (A.P. Tsai) … But also soM condensed maNer.
SoM condensed maNer K. Hayashida, 2007.
i-‐AlLiCu (Dubost, Sainfort, Audier) ZnMgY, I.R Fisher et al.
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Symmetry of quasicrystals
Courtesy A.P. Tsai
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Quasicristal diffracDon paNern
i-‐AlCuFe 10-‐fold symmetry Bragg peaks No periodicity τ=(1+√5)/2=1.618
1 τ τ2 τ3
(from A.P. Tsai)
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DiffracDon paNern of quasicrystals • X-‐ray diffrac=on along 5-‐fold axis. i-‐AlPdMn. ESRF. (Log I scale) • Only few very strong Bragg. τ scaling of posi=on (Fm35).
100
1000
104
105
106
107
108
109
1010
0 0.5 1 1.5 2 2.5 3 3.5
Inte
nsity
Qxpar
(2π/a6D
Unit)
3/4
7/11 18/292/1 47/766 integer
indices N/M short hand notation (Gratias et al.)
1 τ τ2 τ3 τ4
Self-‐similarity : τ=(1+√5)/2=1.618
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• High resolu=on, coherent setup (ID20, ESRF): one speckle
dQ=10-‐4 Å-‐1 ξ ~ 10μm
• Rocking curve: 0.005° FWHM
• Dynamical diffrac=on is also observed
i-‐Al69.8Pd21Mn9.2 Single grain
A. Létoublon et al.
Quasicrystal: Highly perfect Order
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Stable quasicrystals
i-‐AlPdMn, growth of cen=meter size single grains by Bridgman and Czokralski methods.
M. Boudard et al. W. Steurer, i-‐AlPdMn Laue
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Quasicrystals
• Where are the atoms?
• Specific physical proper=es? Phason, modeling and stabilizing
mechanisms.
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Quasicrystals
• Where are the atoms?
• Specific physical proper=es? Phason, modeling QC and stabilizing
mechanisms.
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Where are the atoms?
Two main routes: • Decorated Penrose Dling Trial and error method • High dimensional crystallography (introduced by de Wolf,
Janner and Janssen 1972-‐1979) Only method to use the data Modeling is necessary • Both method are using -‐ Periodic ‘approximant’ -‐ Cluster descrip=on.
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The Penrose Dling (1974)
Diffrac=on: Alan Mackay (82) Mosseri and Sadoc 3D: Amman =ling
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Approximants, clusters and local icosahedral order • Bergman-‐Pauling-‐Samson cluster descrip=on Acta Cryst. 10, 254 (1957). Example of the ZnAl-‐Mg alloy • First QC models: Quasicrystal and approximant. Decora=on
with atomic clusters (V. Elser and Henley PRL 1985 -‐ M. Audier and P. Guyot Phil Mag 1985)
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Amman decorated Dling
• DecoraDon of the Penrose Dling using clusters (Levine and Steinhardt PRL 84; Elser-‐Henley, PRL 1985; Guyot-‐audier Phil Mag 1985)
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superspace crystallography same structural tool
for all aperiodic crystals
Invented by P.M. de Wolff, A. Janner and T. Janssen for incommensurate phases (2014 Ewald Prize)
For quasicrystals: ‘re-‐invented ‘ by -‐ Kalugin, Levitov, Kitaev (jetp, 85)
-‐ Bak (PRL 85) -‐ Duneau and Katz (PRL 85)
-‐ Elser (PRL 85)
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Superspace crystallography
In this 2D reciprocal plane All Bragg peaks posi=ons are expressed as a linear combinaDon of 4 vectors Q=n1a*+n2b*+n3c*+n4d*
4 integers: 4 dimensional space Icosahedral phase:6 indices
(from A.P. Tsai)
b*
a* c*
d*
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Bergman cluster (Frank-‐Kasper type)
Mackay cluster
Tsai cluster (Yb-‐Cd type)
The three Icosahedral QC families
(Courtesy C. Pay Gomez)
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Clusters, Dlings, connecDvity and superspace
• T
2-fold and 3-fold cluster connexion
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Not a Dling. Cluster center posiDon
The 12-fold Penrose vertices distribution
H. Takakura, C. Gomez, A. Yamamoto et al., Nature Materials, , 2007,6,58
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Where are the atoms: CdYb quasicrystal and approximant
• Binary stable quasicrystal : i-‐Cd5.7Yb (Tsai A P, Guo J Q, et al. 2000 Nature 408 537.)
• Periodic Cubic Approximants 1/1-‐Cd6Yb and 2/1-‐Cd5.8Yb, with known structure. (Gomez C. P. and Lidin S.: Phys. Rev. B 68 (2003) 024203).
• Very good chemical order: large and small atoms. • Same atomic clusters • QC: Synchrotron data (5000 Bragg peaks, weak ones) • QC: Phasing and 6D modeling plus Finng tools • Structure of the quasicrystal is well understood (Takakura et al. Nat Mat, 2007)
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Cluster in approximant and QC
Disordered Cd tetrahedron
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Cluster in approximant and QC
Cd dodecahedron
R=4.6 Å
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Cluster in approximant and QC
Yb Icosahedron
R=5.6 Å
CHEMICAL ORDER
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Cluster in approximant and QC
Cd icosidodecahedron
Small distorsions
R=6.5 Å
CHEMICAL ORDER
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Cluster in approximant and QC
Cd Triacontahedron and midle edges
R=7.8 Å
Total 158 atoms
Gomez C P and Lidin S 2003 Phys. Rev. B 68 024203\1.
Closed packed structure, small (Cd) and large (Yb) atom.
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Same cluster in quasicrystal and approximant
15.6 Å
158 atoms. Chemical order Closed packed structure with a large and a small atom.
Same cluster connecBvity in the QC and approximant: 2-‐fold and 3-‐fold bonds
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Cluster connexion 1/1 approximant
• BCC Packing. 2-‐fold and 3-‐fold connected
2-fold connection b=15.7 Å
3-fold connection c=13.6 Å
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Cd6Yb 1/1 and Cd5.8Yb 2/1 approximant
2-fold connection b=15.7 Å
3-fold connection c=13.6 Å
1/1: 15.7 Å 2/1: 25.3 Å
Gomez C P and Lidin S 2003 Phys. Rev. B 68 024203\1.
3 building blocks
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i-CdYb Modeling 6D Modeling related to cluster description
Network of interpenatrating Triacontahedra 2- and 3-fold connected
H. Takakura, C. Gomez, A. Yamamoto et al.
Remaining space is filled with the prolate and oblate (same decoration as in the 2/1 approximant)
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i-CdYb Atomic clusters New environments
Bergman Cluster
H. Takakura, C. Gomez, A. Yamamoto et al., Nature Materials, , 2007,6,58
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PosiDon of the cluster centers
Quasicrystal:Hierachical packing of clusters
H. Takakura, C. Gomez, A. Yamamoto et al., Nature Materials, , 2007,6,58
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Clusters are distorted in the quasicrystal
• Inner tetrahedron plays a crucial role • It breaks the cluster shell icosahedral
symmetry. • Overall icosahedral symmetry with different
cluster orientation
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Quasicrystals
• Where are the atoms?
• Specific physical proper=es? Phason, QC modeling and stabilizing
mechanisms.
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Can quasiperiodic long range order propagates with local rules?
Matching rules are not local growing rules
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Oxford Math building Texas A M University
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Matching rules are not growing rules
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Can quasiperiodic long range order propagates with local rules?
• Matching rules are not growing rules, but possible to grow with a few defects.
• Which atomic surfaces for matching rules?? Icosahedral bounded by 2-fold planes (Katz and Gratias). Set of polyhedra to be used.
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Phason modes and random Dlings
• Phason modes are a specific excita=on for all aperiodic crystals:
-‐ incommensurately modulated phases -‐ Incommensurate composites (sliding mode) -‐ Quasicrystals
• Hydrodynamic theory of aperiodic crystal. (P. Bak, Kalugin et al., Lubenski et al.)
• Diffusive excita=ons
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Phason modes in QC
Invariance of the system free energy with respect to perp space translation: phason modes
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Phason modes in QC
Invariance of the system free energy with respect to perp space translation: phason modes
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Phason mode: Collective diffusive process (non propagative) S(Q+q, t) is decaying exponentially
Ico phase: K2 and K1 elastic constants
Phason modes in all aperiodic phases
Local atom ‘flip’
LS à SL
Phason mode and hydrodynamic theory
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Local atom ‘flip’
LS à SL
Phason mode and hydrodynamic theory
Phason mode: Collective diffusive process (non propagative) S(Q+q, t) is decaying exponentially
Ico phase: K2 and K1 elastic constants
Phason modes in all aperiodic phases
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Phason dynamics: hydrodynamic (Engel and Trebin PRL 2012)
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Quasicrystal Stabilizing mechanisms? • Quasicrystal versus
approximant 1/1-‐Cd6Yb : cubic 1.57 nm 2/1-‐Cd5.8Yb: cubic: 2.53 nm i-‐Cd5.7Yb : quasicrystal ico • ‘FrustraDon’ might be
resolved in 1/1 but not in the QC
• Cd-‐Yb hybridizaDon (Ishii)
• Phason modes? 1/1 local environment (Ishimasa) Two sites CN16-‐CN17
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What mechanisms stabilize quasicrystals? Free Energy = E -‐TS Energy term Close Packing of large (Sc) and small (Zn) atom Electronic stabiliza=on (Hume-‐Rothery, …) sp-‐d hybridiza=on in Zn-‐Sc
Entropy term Vibra=onal entropy Chemical Disorder Phason modes: only in the QC
Random Tiling (Henley and Elser)
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Mechanisms stabilizing quasicrystals
Random Dling and atomic scale modeling. • C. L. Henley: Random =ling models, in Quasicrystals: the state of the art (Eds. D. P. DiVicenzo and P. Steinhardt), p. 429-‐524. 1991
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Modeling quasicrystals
Tilings or 6D models and oscilla=ng pair poten=als Applied to the i-‐CdYb type quasicrystal
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The CdYb type QC and approximant
15.6 Å
~ 34
0 Å
15.6 Å 158 atoms. Chemical order
H. Takakura, C. Gomez, A. Yamamoto et al., Nature Materials, , 2007,6,58
Periodic Approximant
Quasicrystal 5-fold plane
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SimulaDons
• Two ingredients: atomic structure and Hamiltonian. • QC Structure: large periodic approximant: 3/2 (to 8/5) approximant with about 3000 atoms
• Adapted Hamiltonian: oscillaTng pair potenTal fived on ab-‐ini=o data (VASP). Fiwng of energies and forces.
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OscillaTng pair potenTal M. Mihalkovic, C. Henley PRB 85, 092102, 2012 FiVed on energy and forces from structures relaxed with VASP
-0.1
-0.08
-0.06
-0.04
-0.02
0
0.02
0.04
0.06
2 3 4 5 6 7 8
Sc-ScZn-ScZn-Zn
E (e
V)
R (Å)
Energy
Forces Nature Materials 6 (2007) 977-984.
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Comparison simulaDon-‐measurement Transverse modes
1/1 approximant Zn-Sc Quasicrystal
Good agreeement. Differences QC and 1/1 are well reproduced.
Nature Materials 6 (2007) 977-984.
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Intensity distribuDon: comparison simulaDon-‐experiment.
0100200300400500600700
2 4 6 8 10 12 14 16
Inte
nsity
/Mon
=200
0 q=0.18 Å-1
150200250300350400450
2 4 6 8 10 12 14 16
Inte
nsity
/Mon
=100
00
q=0.54 Å-1
150200250300350400450
2 4 6 8 10 12 14 16
Inte
nsity
/Mon
=100
00
q=0.63 Å-1
300400500600700800900
2 4 6 8 10 12 14 16
Inte
nsity
/Mon
=200
00
E (meV)
q=0.82 Å-1
100200300400500600700
2 4 6 8 10 12 14 16
Inte
nsity
/Mon
=100
00 q=0.18 Å-1
100
200
300
400
500
600
2 4 6 8 10 12 14 16
Inte
nsity
/Mon
=100
00 q=0.53 Å-1
100
200
300
400
500
2 4 6 8 10 12 14 16
Inte
nsity
/Mon
=100
00
q=0.62 Å-1
100150200250300350400450
2 4 6 8 10 12 14 16
Inte
nsity
/Mon
=100
00
E (meV)
q=0.79 Å-1
0
5 10-5
0.0001
0.00015
0.0002
0.00025
0.0003
0.00035
4 8 12 16 20 24 28
Inte
nsity
q=+0.165 Å-1
0
5 10-5
0.0001
0.00015
0.0002
0.00025
0.0003
4 8 12 16 20 24 28
Inte
nsity
q=+0.30 Å-1
0
5 10-5
0.0001
0.00015
0.0002
0.00025
0.0003
4 8 12 16 20 24 28
Inte
nsity
q=+0.43 Å-1
0
2 10-5
4 10-5
6 10-5
8 10-5
0.0001
4 8 12 16 20 24 28
Inte
nsity
E (meV)
q=-0.45 Å-1
TA- c-ZnSc TA i-ZnMgSc LA- c-ZnSc
0
0.0005
0.001
0.0015
4 8 12 16 20 24 28
Inte
nsity
q=0.17 Å-1
00.00010.0002
0.00030.00040.0005
0.00060.0007
4 8 12 16 20 24 28
Inte
nsity
q=0.30 Å-1
0
0.0001
0.0002
0.0003
0.0004
0.0005
0.0006
0.0007
4 8 12 16 20 24 28
Inte
nsity
q=0.43 Å-1
0
5 10-5
0.0001
0.00015
0.0002
0.00025
0.0003
4 8 12 16 20 24 28
Inte
nsity
E (meV)
q=-0.43 Å-1
LA- i-ZnMgSc
Blue curve: simulation
Excellent quantitative agreement
The atomistic simulation is validated
Nature Materials 6 (2007) 977-984.
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0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0 5 10 15 20 25
dospart
TetraDodeca-nbdodeca-nc
Part
ial V
DO
S
E (meV)
Mode analysis: Partial density of vibrational
sates • Tetrahedra shows low energy mode, espacially in 1/1 approximant: cluster modes??
• Strong distortion of the dodecahedron both in 1/1 and 3/2 approximant.
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ZnSc cubic approximant.QuasielasDc Neutron and simulaDon: Tetrahedron ‘jump’
A unique dynamical flexibility: displact 0.5 Å Jump Dme scale: 1 ps at RT, 0.3 ps at 170K
H. Euchner, T. Yamada et al . , JPCM 2012, 24, 415403 T. Yamada, H. Euchner et a l , JPCM 2013, 25 , 205405
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i-‐ZnMgSc and i-‐ZnAgSc quasicrystals
Jump of the tetrahedron also in the quasicrystal. Gradual freezing as in a glassy system: at RT only about 30% jumps Related to the large number of local environt At RT in QC an excepDonal dynamical flexibility
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i-‐ZnMgSc and i-‐ZnAgSc quasicrystals
At RT in QC an excepDonal dynamical flexibility
H. Euchner, T. Yamada, et al. J. Phys.: Condens. Maver, 25, 115405, (2013)
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Phason modes in quasicrystals
Hydrodynamic theory and elasDcity: Phenomenological theory
Long wavelength phason modes: diffuse scaNering
I(QBragg+q)= IBragg+ IDiffus(Phonons)+IDiffus(Phasons)
Phasons diffuse scavering :
-‐ Near Bragg peaks (similar to TDS)
-‐ Anisotropy of diffuse scavering: two parameters: phason elasDc constants K1 and K2
Phason modes are diffusive modes, unlike phonons
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i-‐AlPdMn : Phason mode and diffuse scaNering
• Diffuse scattering is reproduced by the hydrodynamic theory: 2 parameters!
• K1/kBT = 0.1 and K2/kBT = -0.03 atom-1
1
10
100
1000
104
105
106
107
108
2.6 2.8 3 3.2 3.4
I (e.
u./Å
3 )
Q (2 /ap unit)π
20/32
1/q2
M. de boissieu et al. PRL 1995 Létoublon et al. Phil Mag Lev 2001
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Phason Diffuse scaNering is observed in all icosahedral QC. Quenched in.
2 parameters for the diffuse scaOering simulaBon!
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i-AlPdMn quasicrystal. In situ T study T evolution of the diffuse Scattering
FROM 750C to 500C
In situ X-ray.
The diffuse scattering is due to pre-transitional fluctuations (3-fold) , with a phason softnening
Agreement with the random-tiling scenario
3fold Boudard, M., et al. (1996). Europhys. Lett. 33(3), 199-204.
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Conclusion
• Good understanding of the atomic structure in the Tsai type QC; excep=onal dynamical flexibility
• Phason modes are characteris=c of the QC state. • RealisDc atomic simulaDon are at work for QC. • Need for new theoreDcal tools for simulaDon analysis
• Stabilizing mechanism of aperiodic crystals remains one of the main challenging ques=on.
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A.P. Tsai, Tohoku University T. Ishimasa, Hokkaido University H. Euchner, ITAP, University of StuOgart, Germany and SIMaP, Grenoble
M. Mihalkovic Academy of Science, BraBslava, Slovakia
T. Yamada, SIMaP, Grenoble and Tokyo University of Science, Noda, Japan
R. Tamura, Tokyo University of Science, Noda, Japan
S. Francoual Petra, Hambourg R. Currat , ILL
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