Structure of Cement Phases Structure of Cement Phases from ab initio - - PowerPoint PPT Presentation

SLIDE 1

Paul Scherrer Institut • 5232 Villigen PSI

14 October, 2008, Le 14 October, 2008, Le Croisic Croisic

Nuclear Energy and Safety Research Department Laboratory for Waste Management

Structure of Cement Phases Structure of Cement Phases from from ab ab initio initio Modeling Modeling

Sergey V. Churakov Sergey V. Churakov

Laboratory for Waste Management Laboratory for Waste Management Paul Scherrer Institute Paul Scherrer Institute Switzerland Switzerland sergey.churakov@psi.ch sergey.churakov@psi.ch

Crystalline C Crystalline C-

• S

S-

• H

H

SLIDE 2

Paul Scherrer Institut • 5232 Villigen PSI

14 October, 2008, Le 14 October, 2008, Le Croisic Croisic

Nuclear Energy and Safety Research Department Laboratory for Waste Management

C C-

• S

S-

• H

H C C-

• S

S-

• H

H C C-

• S

S-

• H Solid Solution Model

H Solid Solution Model

Lothenbach Lothenbach &Winnefelf(2006) after &Winnefelf(2006) after Kulik Kulik & & Kersten Kersten (2001) (2001)

Cement Phase Composition Cement Phase Composition

Lothenbach Lothenbach et al. (2008) et al. (2008)

SLIDE 3

Paul Scherrer Institut • 5232 Villigen PSI

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Nuclear Energy and Safety Research Department Laboratory for Waste Management

Possible end Possible end-

• Members

Members for Amorphous C for Amorphous C-

• S

S-

• H Solid Solutions

H Solid Solutions

CSH (I): CSH (I): Tobermorite Solid Solution Ca Tobermorite Solid Solution Ca5

5-

• x

xSi

Si6

6O

O17

17-

• 2x

2x(OH)

(OH)2x

2x ×

×5H 5H2

2O

O Ca/Si = 0.60 Ca/Si = 0.60 – – 0.75 0.75 Ca Ca4

4Si

Si6

6O

O15

15(OH)

(OH)2

2 ×

×5H 5H2

2O

O – – Ca Ca4.5

4.5Si

Si6

6O

O16

16(OH)

(OH) × ×5H 5H2

2O

O C C-

• S

S-

• H (II):

H (II): Normal Tobermorite Normal Tobermorite – – Jennite Jennite Solid Solution Solid Solution Ca/Si = 0.75 Ca/Si = 0.75 – – 1.50 1.50 Ca Ca4.5

4.5Si

Si6

6O

O16

16(OH)

(OH) × ×5H 5H2

2O

O – – Ca Ca9

9Si

Si6

6O

O18

18(OH)

(OH)6

6 ×

×8H 8H2

2O

O Xonotlite Xonotlite: : Ca Ca6

6Si

Si6

6O

O17

17(OH)

(OH)2

2

Further relevant C Further relevant C-

• S

S-

• H Phases

H Phases

C C-

• S

S-

• H (I):

H (I): Anomalous Anomalous – – Normal Tobermorite Normal Tobermorite Solid Solution Solid Solution Ca/Si = 0.60 Ca/Si = 0.60 – – 0.75 0.75 Ca Ca4

4Si

Si6

6O

O15

15(OH)

(OH)2

2 ×

×5H 5H2

2O

O – – Ca Ca4.5

4.5Si

Si6

6O

O16

16(OH)

(OH) × ×5H 5H2

2O

O

SLIDE 4

Paul Scherrer Institut • 5232 Villigen PSI

14 October, 2008, Le 14 October, 2008, Le Croisic Croisic

Nuclear Energy and Safety Research Department Laboratory for Waste Management

Basic Structural Elements of C Basic Structural Elements of C-

• S

S-

• H Phases

H Phases

Xonotlite

Ca6Si6O17(OH)2

11 Å 11 Å Tobermorite

Ca4+xSi6O15+2x(OH)2-2x×5H2O 7 Å 7 Å 11 Å 11 Å a a b b b b c c

Jennite Jennite

Ca9Si6O18(OH)6×8H2O b b c c

Ca Ca-

• Layer

Layer Silicate chain Silicate chain

SLIDE 5

Paul Scherrer Institut • 5232 Villigen PSI

14 October, 2008, Le 14 October, 2008, Le Croisic Croisic

Nuclear Energy and Safety Research Department Laboratory for Waste Management

Method Method

k k k

R R U dt R d M ∂ ∂ − = ) (

2 2

Molecular Dynamics (MD) Molecular Dynamics (MD)

Structure:

• Bond distances
• Crystallographic positions
• …

Dynamics:

• IR spectra
• Diffusion
• …

}) { }, ({

k k

R R & Γ

Average over Average over Ensemble Ensemble

Newton Equation Newton Equation Ensemble Ensemble of position and velocities

• f position and velocities

Thermodynamics:

• Energies
• Temperature
• …

Must be known Must be known

SLIDE 6

Paul Scherrer Institut • 5232 Villigen PSI

14 October, 2008, Le 14 October, 2008, Le Croisic Croisic

Nuclear Energy and Safety Research Department Laboratory for Waste Management

• Ab Initio methods

Solve Schrödinger equation to obtain energy and forces

• Empirical force field methods

intra-molecular: harmonic bond stretching, bending … inter-molecular: electrostatic and van der Waals interaction

Interaction Potentials Interaction Potentials

Ab Ab Initio Initio <=> <=> Empirical Empirical

Computationally expensive ☺ Valid for any P-T conditions and chemistry ☺ Correct description of bond breaking/forming up to ~ n×10 2 atoms up to ~ n×10 ps ☺ Fast computation Must be calibrated for the system of interest Fail to describe bond breaking/forming ☺ up to ~ n×10 6 atoms ☺ up to ~ n×10 2 ns

Ψ = Ψ + Ψ ∇ − E U m

2 2

2 h

SLIDE 7

Paul Scherrer Institut • 5232 Villigen PSI

14 October, 2008, Le 14 October, 2008, Le Croisic Croisic

Nuclear Energy and Safety Research Department Laboratory for Waste Management

Density functional theory Density functional theory

Hohenberg & Kohn, 1964; Kohn & Sham 1965;

) ( ) (

3 3 N N

R E R H Ψ = Ψ

Schrödinger Equation

• Exact Hamiltonian
• 3N dimensional problem

far too complex :-((

∑

=

i i el

r r

2

) ( ) ( ψ ρ

Kohn-Sham Equation

⎪ ⎩ ⎪ ⎨ ⎧ = = ) ( ) ( ......... ) ( ) (

3 3 3 1 1 3 1

r r H r r H

N KS N N KS KS KS

ψ ε ψ ψ ε ψ

4 3 4 2 1 4 8 4 7 6 4 4 4 4 4 4 4 3 4 4 4 4 4 4 4 2 1 4 8 4 7 6 4 8 4 7 6 8 7 6

ion Approximat effects Quantum el xc Exact Electrons n Interactio Coulomb el Hartree Electrons Nuclei n Interactio Coulomb nuc ext Electrons

• f

Energy Kinetic KS

V V R V H

2

] [ ˆ ] [ ˆ ) ( ˆ 2 1 ρ ρ + + + ∇ − =

−

• Approximate Hamiltonian
• 3 dimensional problem

but can be solved ! :-)) Major uncertainty

SLIDE 8

Paul Scherrer Institut • 5232 Villigen PSI

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Nuclear Energy and Safety Research Department Laboratory for Waste Management

Approximations for Exchange and Correlation functional Approximations for Exchange and Correlation functional

• local density approximation (LDA)
• generalized gradient approximation (BLYP, PBE, ....)

xc

V ˆ

)] ( [ ˆ r V

el xc ρ

)] ( ), ( [ ˆ r r V

el el xc

ρ ρ ∇

∑

−

=

k kr k i i i

e c , ψ

Basis set Basis set

Plane Waves

∑

=

μ μ μϕ

ψ

, i i

c

n m l r

z y x Ne n m l

2

) , , , (

α μ α

ϕ

−

=

Gaussian basis set homogeneous electron gas

Pseudopotential approximation Pseudopotential approximation

Core Region Valence Region

1 2 3 4

3s pseudowavefunction 3s true wavefunction

R [bohr] 1 2 3 4 R [bohr]

3s 2s 1s

Radial Electron Wavefuctions in Si Atom Core Region Valence Region

an example for Si atom

all electro vs. pseudo wavefunctions

SLIDE 9

Paul Scherrer Institut • 5232 Villigen PSI

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Nuclear Energy and Safety Research Department Laboratory for Waste Management

• CPMD code

(used for oblique supercell)

• Plane Wave basis set
• 70 Ry cut-off
• BLYP functional, MT-pseudopotentials
• Car-Parrinello MD
• CP2K/Quickstep code (used for orthogonal supercell)
• Gaussian and Plane Wave basis set
• Triple-ζ basis for O and H, double-ζ for Si and Ca
• PBE functional, Goedeker - pseudopotentials
• Born Oppenheimer MD

DFT approach used in this work DFT approach used in this work

SLIDE 10

Paul Scherrer Institut • 5232 Villigen PSI

14 October, 2008, Le 14 October, 2008, Le Croisic Croisic

Nuclear Energy and Safety Research Department Laboratory for Waste Management

Xonotlite Xonotlite

Q

2

Q

3

Ideal structure from X Ideal structure from X-

• ray studies:

ray studies:

Possible defect formation mechanism Possible defect formation mechanism { {Si} Si}X

X Si Si + 2H

+ 2H2

2O ={4H}

O ={4H}X

X Si Si + SiO

+ SiO2

2

2000 2400 2800 3200 3600 3800

• arb. units

νΗ [cm ]

• 1

Calculated IR spectra Calculated IR spectra

Experimental Observations Experimental Observations

EDS: EDS:

• Ca:Si

Ca:Si > 1.0 in disordered samples > 1.0 in disordered samples

NMR: NMR:

• Presence of both Q

Presence of both Q2

2, Q

, Q3

3 and Q

and Q1

1 sites

sites

• Presence OH with different environment

Presence OH with different environment and molecular H and molecular H2

2O

O

IR and TG/DTA: IR and TG/DTA:

• Presence of molecular H

Presence of molecular H2

2O

O

4000 2000 3000

Experimental Experimental

Ca6Si6O17(OH)2

CPMD, BLYP, MT-PP, 80 Ry

SLIDE 11

Paul Scherrer Institut • 5232 Villigen PSI

14 October, 2008, Le 14 October, 2008, Le Croisic Croisic

Nuclear Energy and Safety Research Department Laboratory for Waste Management

Assumed Defect Formation Mechanism Assumed Defect Formation Mechanism

Δ Δ5 kJ/mol 5 kJ/mol Δ Δ57 kJ/mol 57 kJ/mol Δ Δ0 kJ/mol 0 kJ/mol Δ Δ40 kJ/mol 40 kJ/mol {8H} {8H}x

x {Q3,Q3} {Q3,Q3}

{4H} {4H}x

x Q3 Q3

{8H} {8H}x

x {Q2,Q3} {Q2,Q3}

{4H} {4H}x

x Q2 Q2

{ {Si} Si}X

X Si Si + 2H

+ 2H2

2O ={4H}

O ={4H}X

X Si Si + SiO

+ SiO2

2 CPMD, BLYP, MT-PP, 80 Ry

Churakov & Churakov & Mandaliev Mandaliev (2008) CCR (2008) CCR

SLIDE 12

Paul Scherrer Institut • 5232 Villigen PSI

14 October, 2008, Le 14 October, 2008, Le Croisic Croisic

Nuclear Energy and Safety Research Department Laboratory for Waste Management

0.2 0.4 0.6 0.8 1.0 0.2 0.4 0.6 0.8 1.0

300K 500K

mole fraction + 2

Thermodynamics of Defects in Xonotlite Thermodynamics of Defects in Xonotlite

× × × ×

+ =

3 3 3 3 3 3

, 8 , 2 4

} H { } Si { Si} { } H { 2

Q Q Q Q Q Q

[ ][ ]

[ ]

⎥ ⎦ ⎤ ⎢ ⎣ ⎡ Δ − =

× × × ×

RT E

Q Q Q Q Q Q

exp Si} { } H { } H { } Si {

2 4 , 8 , 2

3 3 3 3 3 3

× ×

3 3 Si}

{ } H {

4 Q Q

×

3 3,

2}

Si {

Q Q ×

3 3,

8}

H {

Q Q

Churakov & Churakov & Mandaliev Mandaliev (2008) CCR (2008) CCR

SLIDE 13

Paul Scherrer Institut • 5232 Villigen PSI

14 October, 2008, Le 14 October, 2008, Le Croisic Croisic

Nuclear Energy and Safety Research Department Laboratory for Waste Management

Structure of Defects in Xonotlite Structure of Defects in Xonotlite

Idealized Structure Idealized Structure Structure with Defects Structure with Defects

Si Si-

• OH

OH {8H} {8H}x

x {Q3,Q3} {Q3,Q3}

Ca Ca-

• OH

OH H H2

2O

O {4H} {4H}x

x Q3 Q3

Churakov & Churakov & Mandaliev Mandaliev (2008) CCR (2008) CCR

SLIDE 14

Paul Scherrer Institut • 5232 Villigen PSI

14 October, 2008, Le 14 October, 2008, Le Croisic Croisic

Nuclear Energy and Safety Research Department Laboratory for Waste Management

IR spectra IR spectra

2000 2400 2800 3200 3600 3800

• arb. units

Q

3

νΗ [cm ]

• 1
• arb. units

O9 O6 O5 O10 O1

2000 2400 2800 3200 3600 3800

4000 2000 3000

νΗ [cm ]

• 1

Ideal Ideal Experimental Experimental Structure with defects Structure with defects Churakov & Churakov & Mandaliev Mandaliev (2008) CCR (2008) CCR

SLIDE 15

Paul Scherrer Institut • 5232 Villigen PSI

14 October, 2008, Le 14 October, 2008, Le Croisic Croisic

Nuclear Energy and Safety Research Department Laboratory for Waste Management

Structure of Structure of 11 Å 11 Å Tobermorite Tobermorite

Normal Tobermorite Ca4.5Si6O16(OH)×5H2O Anomalous Tobermorite Ca4Si6O15(OH)2×5H2O

SLIDE 16

Paul Scherrer Institut • 5232 Villigen PSI

14 October, 2008, Le 14 October, 2008, Le Croisic Croisic

Nuclear Energy and Safety Research Department Laboratory for Waste Management

Anomalous Anomalous 11 Å

11 Å Tobermorite

Tobermorite

Ca4Si6O15(OH)2×5H2O 20 ps NVE ab ab initio initio MD trajectory T~ 310 K

cp2k/QuickStep/GPW, PBE, DZP(Ca,Si), TZ2P(O,H)

SLIDE 17

Paul Scherrer Institut • 5232 Villigen PSI

14 October, 2008, Le 14 October, 2008, Le Croisic Croisic

Nuclear Energy and Safety Research Department Laboratory for Waste Management

O2 O1 O7 W2 W2

b c

W2 W6 O1,O7

a c

W1,3

O6 W6 W2 W6 O1,O7

a c

W1,3

O6 W6 W2

A C

W6

b c

O6 W6 W1 W2 W3 W1 W3 O7,W2 O1,W2

B D

Preserential Preserential orientation of water molecules

• rientation of water molecules

in anomalous in anomalous 11 Å

11 Å Tobermorite

Tobermorite

Churakov (2009) Amer. Miner. Churakov (2009) Amer. Miner.

SLIDE 18

Paul Scherrer Institut • 5232 Villigen PSI

14 October, 2008, Le 14 October, 2008, Le Croisic Croisic

Nuclear Energy and Safety Research Department Laboratory for Waste Management

W6

b c

O6 W6 W1

Preferential orientation of water molecules Preferential orientation of water molecules in anomalous in anomalous 11 Å

11 Å Tobermorite

Tobermorite

2

• 2

1

• 1

1

• 1

5 20 10 15

ΔRHB, [Å] h(t)

t, [ps]

2

• 2

1

• 1

1

• 1

ΔRHB, [Å] h(t)

5 20 10 15

t, [ps]

W6

b c

O6 W6 W1 W2 W3 W1 W3 O7,W2 O1,W2

• 3
• 2
• 1

1 2 3

W1 W3

c, [Å] a r b . u n i t s

Churakov (2009) Amer. Miner. Churakov (2009) Amer. Miner.

• 3
• 2
• 1

1 2 3

W1 W3

• arb. units

506K 321K 506K 321K

c, [Å]

SLIDE 19

Paul Scherrer Institut • 5232 Villigen PSI

14 October, 2008, Le 14 October, 2008, Le Croisic Croisic

Nuclear Energy and Safety Research Department Laboratory for Waste Management

Normal Normal 11 Å

11 Å Tobermorite

Tobermorite

Merlino et al. (2001) X-ray diffraction

Ca4.5Si6O16(OH)×5H2O

SLIDE 20

Paul Scherrer Institut • 5232 Villigen PSI

14 October, 2008, Le 14 October, 2008, Le Croisic Croisic

Nuclear Energy and Safety Research Department Laboratory for Waste Management

Normal Normal 11 Å

11 Å Tobermorite

Tobermorite

Merlino et al. (2001) X-ray diffraction

Ca4.5Si6O16(OH)×5H2O

Set I Set II Set III Set IV Set V a b Set 0

Ca2*

Supercell setup Supercell setup

SLIDE 21

Paul Scherrer Institut • 5232 Villigen PSI

14 October, 2008, Le 14 October, 2008, Le Croisic Croisic

Nuclear Energy and Safety Research Department Laboratory for Waste Management

Normal Normal 11 Å 11 Å Tobermorite Tobermorite

Ca4.5Si6O16(OH)×5H2O

AI MD, PBE, cp2k/QuickStep/GPW, 310 K

Snapshot form ab initio MD

Churakov (2009) EJM Churakov (2009) EJM

SLIDE 22

Paul Scherrer Institut • 5232 Villigen PSI

14 October, 2008, Le 14 October, 2008, Le Croisic Croisic

Nuclear Energy and Safety Research Department Laboratory for Waste Management

Normal Tobermorite Normal Tobermorite

X-ray diffraction Snapshot form ab initio MD

Merlino et al. (2001) cp2k/QuickStep/GPW, PBE, 310 K

SLIDE 23

Paul Scherrer Institut • 5232 Villigen PSI

14 October, 2008, Le 14 October, 2008, Le Croisic Croisic

Nuclear Energy and Safety Research Department Laboratory for Waste Management

W6 W1,3 W2 W6 W2 W6 W6 O6 O6 O1,7 O6 O6 W3 W1 O7 O1 O1,7 O2

c a c a c b

Structure of interlayer Ca ion Structure of interlayer Ca ion in Normal Tobermorite in Normal Tobermorite

Churakov (2009) EJM Churakov (2009) EJM

SLIDE 24

Paul Scherrer Institut • 5232 Villigen PSI

14 October, 2008, Le 14 October, 2008, Le Croisic Croisic

Nuclear Energy and Safety Research Department Laboratory for Waste Management

Calculated vibrational density of state Calculated vibrational density of state Normal Normal 11

11 Å Å Tobermorite

Tobermorite

2600 2800 3000 3200 3400 3600 3800 4000

OH6 W1, W3 W2

CaW2

W6

CaW1, W3 Ca

• arb. units

ν, cm

• 1

Measured IR spectra Measured IR spectra

Yu et al. (1999)

4000 3600 3200 2800

3600 3300

ν, cm

• 1

O2 O1 O7 W2 W2

b c

W2 W6 O1,O7

a c

W1,3 O6 W6 W2 W6 W2 W6 O6 O6 W3 W1 O7 O1

c b

Churakov (2009) EJM Churakov (2009) EJM

SLIDE 25

Paul Scherrer Institut • 5232 Villigen PSI

14 October, 2008, Le 14 October, 2008, Le Croisic Croisic

Nuclear Energy and Safety Research Department Laboratory for Waste Management

Jennite Jennite Experimental Observations Experimental Observations

NMR: NMR:

• Presence of both Q

Presence of both Q2

2, and Q

, and Q1

1 sites

sites

• Presence both >Si

Presence both >Si-

• OH and >Ca

OH and >Ca-

• OH linkage

OH linkage

XRD: XRD:

• Presence of both Q

Presence of both Q2

2 sites only

sites only

• Presence >Ca

Presence >Ca-

• OH linkage only

OH linkage only

Ca9Si6O18(OH)6×8H2O Bonaccorsi et al. (2004)

SLIDE 26

Paul Scherrer Institut • 5232 Villigen PSI

14 October, 2008, Le 14 October, 2008, Le Croisic Croisic

Nuclear Energy and Safety Research Department Laboratory for Waste Management

Jennite Jennite

Ca9Si6O18(OH)6×8H2O

W1 W2 O2 O12 O11 O2 O11 O13 O14 O13 O12

b c

W1 W2 O2 O12 O11 O2 O11 O13 O14 O13 O12

b c

310 K MD CPMD, BLYP, MT-PP, 70 Ry

Dynamic Proton Distribution Dynamic Proton Distribution

R[W1H] - R[O8H]

R[O8-W1]

2.0 2.5 3.0

O8..H..W1 O8..H..W2 O8..H..O13

R[W1H] - R[O8H]

R[O8-W1]

2.0 2.5 3.0 R[W1H] - R[O8H]

R[O8-W1]

2.0 2.5 3.0

• 1.0
• 0.5

0.0 0.5 1.0

O8..H..O13 O8..H..W2 O8..H..W1

ΔE = 10-15 kJ mol-1

log(ρH(Γ)) ~ -ΔE/kT

Churakov (2008) CNR Churakov (2008) CNR

SLIDE 27

Paul Scherrer Institut • 5232 Villigen PSI

14 October, 2008, Le 14 October, 2008, Le Croisic Croisic

Nuclear Energy and Safety Research Department Laboratory for Waste Management

Summary Summary structure of C structure of C-

• S

S-

• H phase

H phase

Xonotlite, Tobermorite and Jennite Xonotlite, Tobermorite and Jennite

• Distribution of water and cations in the interlayer of tobermor

Distribution of water and cations in the interlayer of tobermorite and jennite ite and jennite

• IR and NMR spectra are interpreted on the basis of calculation

IR and NMR spectra are interpreted on the basis of calculation

• Preferential formations of defects in Q

Preferential formations of defects in Q3

3 sites in xonotlite

sites in xonotlite

• Preferential stability of defects in bridging tetrahedra of CSH

Preferential stability of defects in bridging tetrahedra of CSH phases phases

• Dangling O

Dangling O-

• sites on the bridging Si tetrahedra of jennite are de

sites on the bridging Si tetrahedra of jennite are de-

• protonated

protonated

• The dangling de

The dangling de-

• protonated sites are likely sorption sites

protonated sites are likely sorption sites

SLIDE 28

Paul Scherrer Institut • 5232 Villigen PSI

14 October, 2008, Le 14 October, 2008, Le Croisic Croisic

Nuclear Energy and Safety Research Department Laboratory for Waste Management

Acknowledgments Acknowledgments

Peter Peter Mandaliev Mandaliev Jan Tits Jan Tits Erich Wieland Erich Wieland Dmitri Dmitri Kulik Kulik Marcella Marcella Iannuzzi Iannuzzi-

• Mauri

Mauri Matthias Matthias Krack Krack