Atomic motion in glasses studied with coherent X-raysustverre.fr/site/images/BDX/ruta.pdf · Bordeaux, 18/11/2016 Atomic motion in glasses studied with coherent X-rays Beatrice Ruta

Bordeaux, 18/11/2016

Atomic motion in glasses studied

with coherent X-rays

Beatrice Ruta

ESRF – Grenoble, France

Glassy systems

X-ray Photon Correlation Spectroscopy

Aging in metallic glasses

Measurements in operando conditions

Atomic dynamics in network & oxide glasses

Conclusions and future perspectives

OUTLINE

Page 2

Glassy systems






OUTLINE

Page 3

Page 4

HARD & SOFT GLASSES

Amorphous materials …

Page 5

HARD & SOFT GLASSES

log

[rel

axat

ion

tim

e ;

vis

cosi

ty]

1/T; packing fraction

glass

• glasses by rapidly cooling the liquid

• colloidal suspensions by increasing

the packing fraction

• granular materials by applying a shear

• chemical gels spontaneously with time

• physical gels by changing external

parameters (i.e. temperature, pressure..)

slow down of the dynamics

… which can be driven in an arrested state …

Page 6

HARD & SOFT GLASSES

… where they display physical aging

every physical observables spontaneously evolve with time

Page 7

HARD & SOFT GLASSES



Temporal evolution

0 5000 10000 15000 20000 250001E10

1E11

1E12

1E13

1E14

403 K

413 K

vis

cosi

ty (

po

ise)

waiting time (s)

423 K Mg65

Cu25

Y10

Busch et al. J. App. Phys. (1998)

Page 8

HARD & SOFT GLASSES



Temporal evolution Thermal history dependence

0 5000 10000 15000 20000 250001E10

1E11

1E12

1E13

1E14

403 K

413 K

vis

cosi

ty (

po

ise)

waiting time (s)

423 K Mg65

Cu25

Y10

polystyrene aged @ 363 K


Cangialosi et al. Phys. Rev. Lett. (2012)

Page 9

HARD & SOFT GLASSES



Temporal evolution Thermal history dependence

0 5000 10000 15000 20000 250001E10

1E11

1E12

1E13

1E14

403 K

413 K

vis

cosi

ty (

po

ise)

waiting time (s)

423 K Mg65

Cu25

Y10


Cangialosi et al. Phys. Rev. Lett. (2012)

polystyrene aged @ 363 K

Understanding and controlling the physical properties requires

information on the ongoing relaxation processes at the microscopic scale

RELAXATION DYNAMICS

Page 10

Information on the relaxation dynamics can be obtained from the decay of the

intermediate scattering function on a scale 2π/Q

0.1 1 10 100 1,0000.0

0.2

0.4

0.6

f(q

,t)

time (s)

2π/Q

τ

tatqf exp),(

(0) ( )( , )(Q,t)

( ) (0) (0)

Q Q

Q Q

tS Q tF

S Q

RELAXATION DYNAMICS

Page 11

Information on the relaxation dynamics can be obtained from the decay of the

intermediate scattering function on a scale 2π/Q

(0) ( )( , )(Q,t)

( ) (0) (0)

Q Q

Q Q

tS Q tF

S Q

0.1 1 10 100 1,0000.0

0.2

0.4

0.6

f(q

,t)

time (s)

2π/Q

τ

tatqf exp),(

τ = time for structural

rearrangements (on ~2/3 Å in

the case of glasses)

Page 12

How can we measure the

relaxation dynamics in a glass?

Glassy systems






OUTLINE

Page 13

X-RAY PHOTON CORRELATION SPECTROSCOPY

Page 14

X-ray Photon Correlation Spectroscopy is the only technique offering the potential to

unravel the dynamics of glass formers around and below Tg (τ~1-104 s, Q ~0.3-4 Å-1)

glasses


Page 15

XPCS uses the partial coherent properties of X-rays at 3rd generation synchrotrons

F. van der Veen & F. Pfeiffer, J. Phys. Cond. Mat. (1998)


Page 16

Information on the dynamics can be obtained by measuring a series of speckles

patterns and quantifying temporal correlations of intensity fluctuations at a

given wave-vector q

The intensity of the speckles is

related to the exact spatial

arrangement of the scatters

inside the system

l/d

d 2

)()(),(

n

triQ

nneQftQI

Information on the microscopic dynamics

t

Glassy systems






OUTLINE

Page 17

METALLIC GLASSES

Page 18

Their widespread use is however blocked by the difficulty of avoiding aging

and crystallization during processing (particularly strong for MGs)

MGs have outstanding properties and carry the promise of many applications.

Applications of MGs

Electronics and computers

Hard disks, sensors, CD,

DVD

Medicine and biology

Prosthesis, cell culture surfaces,

surgery tools

Tools and machine tools

Gears, micro-servo motors

Environmental applications

Fuel cells, H2 membranes

FIRST INVESTIGATION OF ATOMIC DYNAMICS IN MGs

Page 19

10 100 1,000 10,0000.0

0.2

0.4

0.6

0.8

1.0

1.2 T=418 K

T=417 K

T=415 K

T=413 K

T=410 K

T=408 K

F(Q

,t)2

t (s)

decreasing TMg65Cu25Y10

liquid

1012

1013

1014

1015

1016

2.4 2.5 2.6 2.7

102

103

104

105

106

visco

sity (p

oise)

Tg

LIQUID

rela

xat

ion

tim

e (s

)

1000/T(1/K)

(Q,t) exp ( / )F t

Fit model: KWW

B. Ruta et al. Phys. Rev. Lett. 2012

Q=max of S(Q)


Page 20

10 100 1,000 10,0000.0

0.2

0.4

0.6

0.8

1.0

1.2 T=418 K

T=417 K

T=415 K

T=413 K

T=410 K

T=408 K

T=393 K

T=388 K

T=383 K

T=373 K

F(Q

,t)2

t (s)

decreasing T

Tg

Mg65Cu25Y10

liquid

glass

1012

1013

1014

1015

1016

2.4 2.5 2.6 2.7

102

103

104

105

106

visco

sity (p

oise)

GLASSTg

LIQUID

rela

xat

ion

tim

e (s

)

1000/T(1/K)

Departure from the liquid curve

(Q,t) exp ( / )F t

Fit model: KWW


Q=max of S(Q)


Page 21

10 100 1,000 10,0000.0

0.2

0.4

0.6

0.8

1.0

1.2 T=418 K

T=417 K

T=415 K

T=413 K

T=410 K

T=408 K

T=393 K

T=388 K

T=383 K

T=373 K

F(Q

,t)2

t (s)

decreasing T

Tg

Mg65Cu25Y10

liquid

glass

1012

1013

1014

1015

1016

2.4 2.5 2.6 2.7

102

103

104

105

106

visco

sity (p

oise)

GLASSTg

LIQUID

rela

xat

ion

tim

e (s

)

1000/T(1/K)

β>1

β<1

DYNAMICAL CROSSOVER AT TG

T>Tg: stationary dynamics, β<1, diffusive motion T<Tg: aging, β>1 , Anomalous stress-dominated dynamics

(Q,t) exp ( / )F t

Fit model: KWW


aging

Departure from the liquid curve Q=max of S(Q)

MICROSCOPIC AGING IN MGs

Page 22

Surprising hierarchy of “anomalous”

dynamical regimes

1 6 7 8 91

10

Mg65

Cu25

Y10

(T/Tg=0.99)

Pd77

Si16.5

Cu6.5

(T/Tg=0.73)

Zr67

Ni33

(T/Tg=0.58)

rescaled annealing time

resc

ale

d r

ela

xati

on

tim

e

stationary

well below Tg, …

fast initial

aging


Page 23

1 6 7 8 91

10

Mg65

Cu25

Y10

(T/Tg=0.99)

Pd77

Si16.5

Cu6.5

(T/Tg=0.73)

Zr67

Ni33

(T/Tg=0.58)


resc

ale

d r

ela

xati

on

tim

e

stationary

well below Tg, …

fast initial

aging


dynamical regimes

Contradiction with the continuous evolution

of macroscopic measurements

Ruta et al. Phys. Rev. Lett. (2012)

Ruta et al. J. Chem. Phys. (2013)

Evenson, Ruta et al. Phys. Rev. Lett. (2015)


Page 24

1 6 7 8 91

10

Mg65

Cu25

Y10

(T/Tg=0.99)

Pd77

Si16.5

Cu6.5

(T/Tg=0.73)

Zr67

Ni33

(T/Tg=0.58)


resc

ale

d r

ela

xati

on

tim

e

stationary

well below Tg, …

fast initial

aging


dynamical regimes

Contradiction with the continuous evolution

of macroscopic measurements

Ruta et al. Phys. Rev. Lett. (2012)

Ruta et al. J. Chem. Phys. (2013)

Evenson, Ruta et al. Phys. Rev. Lett. (2015)

Cipelletti et al. Phys. Rev. Lett. (2000)

Similar to what observed in soft materials

(colloidal gels, emulsions, polymeric gels, …)

waiting time (s)

fast initial

aging

slow

aging re

laxa

tio

n tim

e (

s)

Universal stress-dominated dynamics?

Page 25

What is the origin of

the microscopic aging?

STRUCTURE & DYNAMICS DURING AGING

Page 26

Combining XRD and XPCS same thermal and temporal protocol

0 500 1000 1500 1800300

350

400

450

500

550

t-t0 (min)

T (

K)

393

433

453 473

493 513

Pd77Si16.5Cu6.5 (Tg=625 K, Q=2.8 Å-1)

Heating rate 3K/min

2 XRD experiments:

i) high resolution around the FSDP

ii) large q range (up to 25Å-1 to extract the pair distribution function G(r))


Page 27

Complementary dynamical (ID10) & structural (ID15) study

0 500 1000 1500100

1000

10000

(

s)

t-t0 (min)

393 433 453 473 493 513

T (K)

Dynamics at Qmax of S(Q)

XPCS (ID10)

fast initial aging

stationary

w 0 w(T, t ) (T)exp(t / )

τ*(393493 K) ~6000 s

• Fast aging along isotherms, strong τ reduction at temperature jumps

• Frozen dynamics at the highest T (513 K)


Page 28

Complementary dynamical (ID10) & structural (ID15) study

rel.

FW

HM

Γ

/Γ0

400 450 500

1.004

1.005

1.006

1.007

1.008

T (K)

V/V

0

0 500 1000 1400

1.004

1.005

1.006

1.007

1.008

t-t0 (min)

V/V

0

0 70 150

433K

Rel

. volu

me

V/V

0=

(Q0/Q

)3

513 K, stable

Evolution of the FSDP

XRD (ID15)

Continuous FSDP sharpening Isothermal volume relaxation

Two main processes controlling the aging:

1) volume shrinking (density changes)

2) medium range ordering (constant density)

fast aging

stationary

regime


Page 29

1.8 2 2.2 2.4 2.67.5

8

8.5

9

9.5

1000/T (K-1

)

log

(

s)

dV

G

Aging time from V/V0τV

Aging time from Γ/ Γ0τΓ

Aging time from τατ*

Three characteristic aging times:

Giordano & Ruta, Nature Commun. 2016

Two main processes controlling the aging:

1) volume shrinking (density changes)

2) medium range ordering (constant density)

fast aging

stationary

regime


Page 30

1.8 2 2.2 2.4 2.67.5

8

8.5

9

9.5

1000/T (K-1

)

log

(

s)

dV

G

Three characteristic aging times:

Giordano & Ruta, Nature Commun. 2016

the evolution between the two could be related to a ductile to

brittle transition

Aging time from V/V0τV

Aging time from Γ/ Γ0τΓ

Aging time from τατ*

Glassy systems






OUTLINE

Page 31

better H2 permeability than crystalline materials (high H2 diffusivity due to the

free volume)

high H2 solubilities and diffusivities

non-precious metals/alloys

Pd: ~20000 euro/Kg

Group IV and V metals ~10-200 euro/Kg

MG MEMBRANES FOR H2 SEPARATION FROM CO2

Page 32

Ni and Zr-based MGs:

Collab. with Prof. D. Chandra

(DOE - NNSA Grant, US)

EFFECT OF H2 ON THE DYNAMICS

Page 33

Ni60Nb40, T=373 K , Qp=2.7 Å-1

H @ 0.6 bar

1

10 100 10000.0

0.2

0.4

0.6

0.8

1.0

annealing times:

0.4h 6.3h

1.3h 7.2h

3.5h 9.1h

4.6h 11 h

5.4h

F(Q

,t)2

t (s)

1


Page 34

Ni60Nb40, T=373 K , Qp=2.7 Å-1

H @ 0.6 bar

Dramatic acceleration of the dynamics due to the hydrogen atmosphere

2

H

V

10 100 10000.0

0.2

0.4

0.6

0.8

1.0

annealing times:

0.4h 6.3h

1.3h 7.2h

3.5h 9.1h

4.6h 11 h

5.4h

F(Q

,t)2

t (s)

2


Page 35

Ni60Nb40, T=373 K , Qp=2.7 Å-1

H @ 0.6 bar

Dramatic acceleration of the dynamics due to the hydrogen atmosphere

Reversible transition: after removing the hydrogen, the dynamics slows

down again but with a faster aging

B. Ruta et al. in progress

H

V

V

10 100 10000.0

0.2

0.4

0.6

0.8

1.0

annealing times:

0.4h 6.3h

1.3h 7.2h

3.5h 9.1h

4.6h 11 h

5.4h

F(Q

,t)2

t (s)

3

3

Glassy systems






OUTLINE

Page 36

1 10 100 1,000 10,0000.0

0.2

0.4

0.6

0.8

1.0

T=723 K

T=693 K

T=668 K

T=648 K

t (s)

F(Q

,t)2

Decreasing T

SILICATE GLASSES: 0.8SIO2-0.2NA2O (NS4, Tg=783 K)

Page 37

Stretched exponential decay of the

correlation function as in the liquid phase

(β=0.67) diffusive motion

Qmax=1.53 Å-1; measurements in the glass

transition region

1 10 100 1,000 10,0000.0

0.2

0.4

0.6

0.8

1.0

T=723 K

T=693 K

T=668 K

T=648 K

t (s)

F(Q

,t)2

Decreasing T

SILICATE GLASSES: 0.8SIO2-0.2NA2O (NS4, Tg=783 K)

Page 38

Qmax=1.53 Å-1; measurements in the glass

transition region

Stretched exponential decay of the

correlation function as in the liquid phase

(β=0.67) diffusive motion

10 100 10000.0

0.2

0.4

0.6

0.8

1.0

10 100 10000.0

0.2

0.4

0.6

0.8

1.0

(g2(Q

max

,t)-

1)/

A

t(s)

ta=1.8 h

ta=3.5 h

ta=5.2 h

isothermal @ T/Tg=0.93

F(Q

,t)2 increasing t

a

t (s)

a

T=723 K

T=693 K

T=668 K

T=648 K

decreasing T

isostructure

Absence of physical aging on the

experimental time scale

COMPARISON WITH DIFFUSION DATA

Page 39

0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.010

-24

10-22

10-20

10-18

10-16

10-14

10-12

10-10

10-8

Na tracer

Na tracer

Na tracer

QNS

QNS

from

NS4-G2

Si-O

dif

fusi

on

(m

2s-1

)

1000/T (K-1)

Na Tg

)(/

)/(1D 2

XPCS

QS

Q

XPCSincoh

incoh

Hempelmann et al, Z. Phys. B (1994)

Kargl et al. Phys. Rev. B. (2006)

XPCS data :

~10 orders of magnitude

slower than the Na diffusion

Closer to the low T

extrapolation of the Si-O matrix

B. Ruta et al., Nat. Commun. (2014)

WAVE VECTOR DEPENDENCE

Page 40

0.0

0.2

0.4

0.6

0.8

1.0

0.0 0.5 1.0 1.5 2.0 2.50

50

100

150

200

(Q) (s)S

(Q)

Q (Å-1)


Page 41

Mezei et al, Physica Scripta (1987)

QNS data of supercooled CKN

0.0

0.2

0.4

0.6

0.8

1.0

0.0 0.5 1.0 1.5 2.0 2.50

50

100

150

200

(Q) (s)S

(Q)

Q (Å-1)


Page 42

Mezei et al, Physica Scripta (1987)

QNS data of supercooled CKN

Horbach et al, Phys. Rev. Lett. (2002)

Meyer et al, Phys. Rev. Lett. (2004)

0.0

0.2

0.4

0.6

0.8

1.0

0.0 0.5 1.0 1.5 2.0 2.50

50

100

150

200

(Q) (s)S

(Q)

Q (Å-1)

Page 43

What happens in oxide glasses?

IRRADIATION-DRIVEN DYNAMICS IN SIO2 AT LOW TEMPERATURE

Page 44

101

102

103

104

0.0

0.2

0.4

0.6

0.8

1.0

1011

1012

1013

1014

0.0

0.2

0.4

0.6

0.8

1.0 b)

(g2(t

)-1

)/c

t [s]

a)

increasing

flux

F0~110

11 ph/s

F1~310

10 ph/s

F2~1.210

10 ph/s

F3~3.610

9 ph/s

(g2(t

)-1

)/c

tF [ph]

SiO2


Page 45

101

102

103

104

0.0

0.2

0.4

0.6

0.8

1.0

1011

1012

1013

1014

0.0

0.2

0.4

0.6

0.8

1.0 b)

(g2(t

)-1

)/c

t [s]

a)

increasing

flux

F0~110

11 ph/s

F1~310

10 ph/s

F2~1.210

10 ph/s

F3~3.610

9 ph/s

(g2(t

)-1

)/c

tF [ph]

SiO2

The atomic motion at room temperature in

SiO2 is completely induced by the

incoming X-rays

10-11

10-10

10-9

102

103

104

(s

)

1/F [ph/s]-1

SiO2, F

0

SiO2, F

1

SiO2, F

2

SiO2, F

3

SiO2 bis, F

0

SiO2 bis, F

1

GeO2, F

0

GeO2, F

2


Page 46

The atomic motion at room temperature in

SiO2 is completely induced by the

incoming X-rays

By varying appropriately the average

incoming flux (flux, exposure time, delay time)

is possible to tune “at will” the dynamics

101

102

103

104

0.0

0.2

0.4

0.6

0.8

1.0

1011

1012

1013

1014

0.0

0.2

0.4

0.6

0.8

1.0 b)

(g2(t

)-1

)/c

t [s]

a)

increasing

flux

F0~110

11 ph/s

F1~310

10 ph/s

F2~1.210

10 ph/s

F3~3.610

9 ph/s

(g2(t

)-1

)/c

tF [ph]

SiO2

NO STANDARD RADIATION DAMAGE

Page 47

The effect of the X-rays is almost instantaneous and leads to a reversible and

stationary atomic motion, thus independent on the global accumulated dose

within the experimental time

X-RAYS & HARD MATTER

Page 48

Three main processes:

Knock-on events require high energy to break bonds

Electronic rearrangements require pre-existing defects

Radiolysis require lifetime of the excitation ~ vibrations ~1ps possible

B. Ruta et al. arXiv (2016)

Hobbs et al. J. Nuclear Mat. (1994)


Page 49





This effect is absent in metallic systems where electronic excitations

are delocalized much faster on ~fs time scale




Page 50





This effect is absent in metallic systems where electronic excitations

are delocalized much faster on ~fs time scale

Hard X-rays as pump and probe of the dynamics


Similar to what observed with

electron transmission microscopy

on bi-dimensional SiO2


Huang et al. Science (2013)

POSSIBILITY TO GET INTRINSIC PROPERTIES OF THE SYSTEM

Page 51

0.0 0.5 1.0 1.5 2.0

100

150

200

250

300

Q (Å-1)

(s

)

SiO2

The wavevector dependence of the

dynamics is independent on the flux

Typical increase as in supercooled

liquids


Page 52

0.0 0.5 1.0 1.5 2.0

100

150

200

250

300

Q (Å-1)

(s

)

SiO2

The wavevector dependence of the

dynamics is independent on the flux

Typical increase as in supercooled

liquids

10 100 1,0001.00

1.01

1.02

1.03

1.04

1.05

ta=1400 s

ta=2600 s

ta=3800 s

ta=16000 s

t [s]

g2(t

)

GeO2

~1.5

The shape of the curve is also

independent on the flux

Compressed in SiO2 and GeO2,

stretched in NS4 and lead-silicates.

Stress-driven vs diffusive dynamics?

Glassy systems






OUTLINE

Page 53

ESRF UPGRADE: EXTREMELY BRILLIANT SOURCE (EBS)

Page 54

XPCS AT EBS

Page 55

The EBS machine will lead to ~100X increase in coherent flux possibility to

measure faster time scales (from 0.1 ms to 0.01 μs) & to go at higher energies (up

to 30 keV)

O. Shpyrko J. Synch, Rad. 2014

XPCS AT EBS

Page 56

MANY NEW SCIENTIFIC OPPORTUNITIES

• protein dynamics in living cells

• dynamics under confinement

• dynamics of polymers,

macromolecules, membranes,

foams, …

• dynamics at buried interfaces

• polyamorphism (LL/GG phase

transitions)

• dynamics at extreme conditions

® Pierre Gilles De Gennes

EBS WORKSHOP

Page 57

Presentation of 8 Conceptual Design Report (CDR) for new possible beamlines

CDR1 - Beamline for coherence applications (XPCS)

CDR2 - Beamline for hard X-ray diffraction microscope

CDR3 - High throughput large field phase-contrast tomography beamline

CDR4 - Surface science beamline

CDR5 - Advanced high-flux nano-XRD beamline for science under extreme conditions

CDR6 - Facility for dynamic compression studies

CDR7 - High brilliance XAS beamline

CDR8 - Serial crystallography beamline

http://www.esrf.eu/home/events/conferences/2016/ebs-science-workshop.html

http://www.esrf.eu/home/events/conferences/2016/ebs-science-workshop/cdr1---coherence-applications.html






http://www.esrf.eu/home/events/conferences/2016/ebs-science-workshop/cdr2---beamline-for-hard-x-ray-diffraction-microscopy.html

http://www.esrf.eu/home/events/conferences/2016/ebs-science-workshop/cdr3---high-throughput-large-field-phase---contrast-tomography-beamline.html

http://www.esrf.eu/home/events/conferences/2016/ebs-science-workshop/cdr4---surface-science-beamline.html

http://www.esrf.eu/home/events/conferences/2016/ebs-science-workshop/cdr5---advanced-high-flux-nano-xrd-beamline-for-science-under-extreme-conditions.html

http://www.esrf.eu/home/events/conferences/2016/ebs-science-workshop/cdr6---facility-for-dynamic-compression-studies.html

http://www.esrf.eu/home/events/conferences/2016/ebs-science-workshop/cdr7---high-brilliance-xas-beamline.html

http://www.esrf.eu/home/events/conferences/2016/ebs-science-workshop/cdr8---serial-crystallography-beamline.html

TAKE HOME MESSAGE

Page 58

Possibility to investigate the slow dynamics in glasses at

the atomic length scale

Depending on the nature of the system and the

competition between intrinsic and induced dynamics is

possible to move from spontaneous density fluctuations

to intensity-driven atomic motion

Many new scientific opportunities with XPCS @ EBS

ACKNOWLEDGMENTS

Page 59

Thank you for your attention!!!

F. Zontone Y. Chushkin

M. Di Michiel

V.M. Giordano

G. Baldi G. Monaco

W. Kob L. Cipelletti

B. Rufflé

1.25 1.30 1.35 1.40 1.45 1.50 1.55

1

2

3

4

Glass

Rc=0.1 K/min

Rc=1 K/minT

g

log

[ (

s)]

1000/T (K-1

)

Liquid

B. Ruta et al., Nat. Commun. (2014)

Ea,glass=70 kJ/mol

Ea,liquid=470 kJ/mol

ACKNOWLEDGMENTS 0.8SIO2-0.2NA2O (NS4, TG=783 K)

STRUCTURAL EVOLUTION

Page 61

380

440

500

560

300

350

400

450

500

102

103

104

0.4

0.6

0.8

1.0

102

103

104

1.48

1.49

1.50

1.51d)c)

b)

F0 fixed spot

F1 fixed spot

F1 each point is measured after

taking data for the dynamics

Are

a [

a.u

.]

a)

I(Q

max)

[a.u

.]

FW

HM

[Å

-1]

global irradiated time [s]

Q

max [

Å-1

]global irradiated time [s]

Occurrence of a real damage for longer

exposure time

Threshold for structural damage

at ~104 s of global irradiation at

maximum flux

NO STANDARD RADIATION DAMAGE

Page 62

The dynamics is independent on the global

accumulated dose

10 100 1,0001.00

1.01

1.02

1.03

1.04

1.05

1400 s

2600 s

3800 s

16000 s

time [s]

g2(t

)

GeO2

T=295 K


Page 63

0.0 0.5 1.0 1.5 2.0

100

150

200

250

300

Q (Å-1)

(s

)

SiO2

0.0 0.5 1.0 1.5 2.0

100

150

200

250

300

(

s)

Q (Å-1)

~0.67NS4

Stretched vs compressed mettere

una figura del confronto curve

Different Q dependence

MICROSCOPIC AGING IN METALLIC GLASSES

Page 64

the evolution between the two could be

related to a ductile to brittle transition

Microscopic aging:

Fast aging: thermal activation of a

cascade of jumps from a high-energy

minimum with irreversible atomic

rearrangements changing density

Stationary: more relaxed (low energy)

minimum. Localized dynamics. no density

change, MRO increase

Fan et al. Phys. Rev. Lett. 2015

RELAXATION DYNAMICS

Page 65

F packing fraction

0.0

0.2

0.4

0.6

0.8

1.0 microscopic relaxation

f (q

,t)

log(t)

structural relaxation

(rattling in the cage)

(cage changes)

1/T temperature

tw waiting time

The slow down of the dynamics toward an arrested state corresponds to a continuous

shift of the decay of the density fluctuations toward longer time scales

RELAXATION DYNAMICS

Page 66

F packing fraction

0.0

0.2

0.4

0.6

0.8

1.0 microscopic relaxation

f (q

,t)

log(t)

structural relaxation

(rattling in the cage)

(cage changes)

1/T temperature

tw waiting time

τ2 structural relaxation time related to a

structural rearrangement of the particles.

fast relaxation

slow relaxation

τ1 microscopic relaxation time related to the

interactions between a particle and the

cage of its nearest neighbors.

The slow down of the dynamics toward an arrested state corresponds to a continuous

shift of the decay of the density fluctuations toward longer time scales

EFFECT OF H2 ON THE STRUCTURE

Page 67

2.0 2.2 2.4 2.6 2.8 3.0 3.2 0 10000 20000 30000400

450

500

550

600

0 10000 20000 300002.910

2.915

2.920

2.925

2.930

0 10000 20000 300000.32

0.34

0.36

0.38

0.40

T=295 K (VI)

T=373 K (VI)

T=373 K (H)

T=373 K (VII)

I(

Q)

(a.u

.)

Q (Å-1

)

Ni0.6

Nb0.4

A

annealing time (s)

Qp (

Å-1

)

annealing time (s)

FW

HM

annealing time (s)

Reversible decreasing of

the intensity of the FSDP

EFFECT OF H2 ON THE STRUCTURE

Page 68

2.0 2.2 2.4 2.6 2.8 3.0 3.2 0 10000 20000 30000400

450

500

550

600

0 10000 20000 300002.910

2.915

2.920

2.925

2.930

0 10000 20000 300000.32

0.34

0.36

0.38

0.40

T=295 K (VI)

T=373 K (VI)

T=373 K (H)

T=373 K (VII)

I(

Q)

(a.u

.)

Q (Å-1

)

Ni0.6

Nb0.4

A

annealing time (s)

Qp (

Å-1

)

annealing time (s)

FW

HM

annealing time (s)

Reversible decreasing of

the intensity of the FSDP

XRD

ID10 Next step: high energy XRD & EFAFS

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Atomic motion in glasses studied with coherent X-raysustverre.fr/site/images/BDX/ruta.pdf · Bordeaux, 18/11/2016 Atomic motion in glasses studied with coherent X-rays Beatrice Ruta