T. CharpentierActinet Workshop, September 23th, 2005 1

A Solid State NMR Study of

a Mixed Alkali Aluminoborosilicate Glass Structure

and its Evolution Under Irradiation

T. Charpentier, M. Gaillard, D. Sakellariou, J. Virlet

Laboratoire de Structure et Dynamique par Résonance Magnétique

Laboratoire Claude Fréjacques, URA 331 CEA / CNRSService de Chimie Moléculaire

CEA Saclay, France.

N. Ollier, B. BoizotLaboratoire des Solides Irradiés

CEA-CNRS-Ecole Polytechnique, France.

T. CharpentierActinet Workshop, September 23th, 2005 2

Overview of the study

• Understanding the effects of ionizing radiations (here e-) on structural changes of nuclear waste glasses, in order to predict the modification of the glass during storage.

• Simulation of the dose (auto) irradiation accumulated during storage by external electron irradiations: Van de Graaff accelarator,1.8 MeV, 20 A beam, ~ 1GGy dose.

• Use of simplified borosilicate glasses (mol.%)

63.47 SiO2- 16.8 B2O3 – 4.04 Al2O3 – 2.35 ZrO2 – 13.34 A2O

A2O =

1) x Na2O - (1-x) Li2O

2) x Na2O - (1-x) K2O

Vitrified waste (CSD-V)

T. CharpentierActinet Workshop, September 23th, 2005 3

(Microscopic) Structural changes induced by irradiations

• Increase of glass polymerization : Si(Q2)Si(Q3)

• Increase of boron in trigonal environments : BO4 BO3

• Formation of molecular oxygen

• Production of paramagnetic defects

B. Boizot et al., NIM B 166-167, (2000) 500N. Ollier et al., JNCS 323, (2003) 200.

Most of the structural changes are assigned to the migration of alkali Segregation of alkali under irradiation ?

These changes are less important in complex glass composition (close to the French Nuclear glass SON68) than simple ones : this could be

explained by the decrease of the alkaline ions mobility

The Mixed Alkali Effect(decreases considerably the alkali motion ) / irradiations

0.1 à 3.5MeV

~1 mm

~ cm

~ 100 %

<< 1 dépl .

{

~ 100 %

< 1 dépl .

{

0.1 à 3.5

MeV

~1 mm

0.1 à 3.5

MeV

~1 mm

0.1 à 3.5MeV

~1 mm

0.1 à 3.5MeV

0.1 à 3.5MeV

~1 mm

~ cm

~ cm

~ 100 %

<< 1 dépl .

{

~ 100 %

< 1 dépl .

{

~ 100 %

<< 1 dépl .

{

~ 100 %

<< 1 dépl .

{

~ 100 %

< 1 dépl .

{

~ 100 %

< 1 dépl .

{

T. CharpentierActinet Workshop, September 23th, 2005 4

The Mixed Alkali Effect

550

560

570

580

590

600

610

620

0 0,2 0,4 0,6 0,8 1

mol.% (Na2O/Na2O+K2O)

Tg

(°C

)

Electrical conductivity (300°C)

-12

-11

-10

-9

-8

0 0.2 0.4 0.6 0.8 1

Na/LiNa/K

Log

m)-1

mol % (Na2O)/(Na

2O+Z)

Tg

MAE : significant decrease of the ionic conductivityCan the MAE cause a reduction of alkali migration under irradiation ?

T. CharpentierActinet Workshop, September 23th, 2005 5

MAS NMR of Quadrupolar Nuclei

TB 05.70

TB 75.110

0B

+3/2

+1/2

-1/2

-3/2

Central transition

2/3I

parameterasymmetry r quadrupola :

constant couplingr quadrupola : 31 ,

shift chemical isotropic :

: shift chemical

2

00

20

2

Q

QQ

iso

Qiso

C

CPB

P

220

2/11

: fields) (two glassesFor Qiso P

T. CharpentierActinet Workshop, September 23th, 2005 6

11B (I=3/2) MAS NMR

TB 05.70 TB 75.110

T. CharpentierActinet Workshop, September 23th, 2005 7

11B MAS / MQMAS NMR

MAS (1d)

MQMAS (2d)

T. CharpentierActinet Workshop, September 23th, 2005 8

11B MQMAS NMR

BO32 sites

BO42 sites

T. CharpentierActinet Workshop, September 23th, 2005 9

11B MAS NMR

B

OB

O O

O

O

B

OB

O O

O

O

B

OB

O

B

O

O

O

O

B

OB

O

B

O

O

O

O

T. CharpentierActinet Workshop, September 23th, 2005 10

11B MAS NMR : Mixed Alkali Effect

T. CharpentierActinet Workshop, September 23th, 2005 11

11B MAS NMR : Mixed Alkali Effect

Non-linear variation of the BO3/BO4 ratio

Na/Li : BO3/BO4 minimum

Na/K : BO3/BO4 maximum

T. CharpentierActinet Workshop, September 23th, 2005 12

11B MAS NMR : irradiation effects Na/Li

BO4 to BO3 conversion

T. CharpentierActinet Workshop, September 23th, 2005 13

11B MAS NMR : irradiation effects Na/K

BO4 to BO4/BO3 conversion No conversion

T. CharpentierActinet Workshop, September 23th, 2005 14

27Al MAS NMR

KCNaCLiC QQQ

T. CharpentierActinet Workshop, September 23th, 2005 15

27Al MAS NMR : Mixed Alkali Effect

AlO4- : Na+ preferential charge compensator ?

T. CharpentierActinet Workshop, September 23th, 2005 16

27Al MAS NMR : irradiation effects Na/K,Na/Li

Cq increases (site distortion increase). MAE : minimized effect

K,Na Na,Li

T. CharpentierActinet Workshop, September 23th, 2005 17

27Al MAS NMR : Mixed Alkali Effect Na/K,Na/Li

Analytical model for f(Cq,nq) : Gaussian Isotropic Model (Cjzjek)

T. CharpentierActinet Workshop, September 23th, 2005 18

27Al MAS NMR : Mixed Alkali Effect Na/K,Na/Li

T. CharpentierActinet Workshop, September 23th, 2005 19

29Si MAS NMR

Na,KLi,Na

T. CharpentierActinet Workshop, September 23th, 2005 20

29Si RAMAN : irradiation effects Na/K,Na/Li

1000 1200

0

3000

6000

1000 1200

0

5000

1000 1200

0

4000

1000 1200

0

5000

1000 1200

0

3000

6000

1000 1200

0

5000

50 Na

25 Na

75 Na 60 Na

100 K

40 Na

1000 1200

0

2000

1000 12000

4000

1000 12000

2000

4000

1000 12000

3000

0 Na

Raman shift (cm-1)

75 Na

Raman shift (cm-1)

25 Na

Raman shift (cm-1)

50 Na

Raman shift (cm-1)

Na/Li

Na/K

50/50

Q2

Q3

Irradiated

Pristine

MAE: modifier migration blocked

Q2Q3

T. CharpentierActinet Workshop, September 23th, 2005 21

29Si MAS NMR / RAMAN

900 1000 1100 12000

3000

6000

Q3

Q2

50/50 Irradiated glassPristine glass

Inte

nsity

(a.

u)

Raman shift (cm-1)

Q2

Q3

Na/Li : Stable polymerization Li : Polymerization increase

1000 12000

2000

Li5a100 % Li

Décalage Raman (cm-1)

T. CharpentierActinet Workshop, September 23th, 2005 22

23Na NMR

Localisation of the alkali after the migration processes

1) migration to the surfaceXPS : No

2) bulk segregation

Can NMR provides measurements to detect it ?

Static (Non-rotating ) sample approach : Relaxation Time Measurment

and SEDOR NMR

T. CharpentierActinet Workshop, September 23th, 2005 23

23Na NMR : longitudinal relaxation

180 90

eqM

0M

rectM

rect

inversion recovery experiment

eqM

32

1

expT

tBA

T. CharpentierActinet Workshop, September 23th, 2005 24

23Na NMR : irradiation effects Na/Li

Na-Na1

111

intersite1

intersite1intrasite11

D

DQ

T

TTT

T. CharpentierActinet Workshop, September 23th, 2005 25

23Na Spin Echo / SEDOR NMR

90

T T

E(T)23Na

7Li

E(T) (Hahn Echo): Na-Na dipolar interactions

180

E(T) (SEDOR): Na-Na + Na-Li dipolar interactions

180

T. CharpentierActinet Workshop, September 23th, 2005 26

23Na Spin Echo / SEDOR NMR

ji ijr

M62

1

LiNaNaNa MM 22

NaNaM 2

T. CharpentierActinet Workshop, September 23th, 2005 27

23Na Spin Echo/SEDOR NMR : irradiation effects Na/Li

: decrease of Na-Li dipolar interactions Na clusterization ?

T. CharpentierActinet Workshop, September 23th, 2005 28

Conclusion

MAE on the glass network structure

Na/K : BO3/BO4 minimum - Na/Li : BO3/BO4 maximum

MAE / irradiation effects

Na/K blocks the migration of BO4 compensators

Na/Li blocks the migration of modifiers

AlO4 – stable : site distortion increase

Na preferential charge compensator ?

Na clusterization?

Ionic Irradiation (Aun+) (underway)N.Ollier et al, Journal of Physics : Condensed Matter 16 (2004) 7625.N.Ollier et al, Journal of Non-Crystalline Solids 341, (2004) 26.

T. CharpentierActinet Workshop, September 23th, 2005 29

Perpectives

0B

NMR of active materials :Auto-irradiation effects

Special containment (rotor) systemSee D. Sakellariou

T. CharpentierActinet Workshop, September 23th, 2005 30

Perpectives : Heteronuclear correlation spectrosocopy

Static sample NMR can be useful