1 T. CharpentierActinet Workshop, September 23th, 2005 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 / CNRS Service de Chimie Moléculaire CEA Saclay, France. N. Ollier, B. Boizot Laboratoire des Solides Irradiés CEA-CNRS-Ecole Polytechnique, France.

2 T. CharpentierActinet Workshop, September 23th, 2005 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.%) SiO B2O3 – 4.04 Al2O3 – 2.35 ZrO2 – A2O A2O = 1) x Na2O - (1-x) Li2O 2) x Na2O - (1-x) K2O Vitrified waste (CSD-V)

3 T. CharpentierActinet Workshop, September 23th, 2005 (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 , (2000) 500 N. 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

4 T. CharpentierActinet Workshop, September 23th, 2005 The Mixed Alkali Effect Electrical conductivity (300°C) Tg MAE : significant decrease of the ionic conductivity Can the MAE cause a reduction of alkali migration under irradiation ?

5 T. CharpentierActinet Workshop, September 23th, 2005 MAS NMR of Quadrupolar Nuclei +3/2 +1/2 -1/2 -3/2 Central transition

6 T. CharpentierActinet Workshop, September 23th, B (I=3/2) MAS NMR

7 T. CharpentierActinet Workshop, September 23th, B MAS / MQMAS NMR MAS (1d) MQMAS (2d)

8 T. CharpentierActinet Workshop, September 23th, B MQMAS NMR BO3 2 sites BO4 2 sites

9 T. CharpentierActinet Workshop, September 23th, B MAS NMR

10 T. CharpentierActinet Workshop, September 23th, B MAS NMR : Mixed Alkali Effect

11 T. CharpentierActinet Workshop, September 23th, B MAS NMR : Mixed Alkali Effect Non-linear variation of the BO 3 /BO 4 ratio Na/Li : BO 3 /BO 4 minimum Na/K : BO 3 /BO 4 maximum

12 T. CharpentierActinet Workshop, September 23th, B MAS NMR :  irradiation effects Na/Li BO 4 to BO 3 conversion

13 T. CharpentierActinet Workshop, September 23th, B MAS NMR :  irradiation effects Na/K BO 4 to BO 4 /BO 3 conversionNo conversion

14 T. CharpentierActinet Workshop, September 23th, Al MAS NMR

15 T. CharpentierActinet Workshop, September 23th, Al MAS NMR : Mixed Alkali Effect AlO 4 - : Na + preferential charge compensator ?

16 T. CharpentierActinet Workshop, September 23th, Al MAS NMR :  irradiation effects Na/K,Na/Li Cq increases (site distortion increase). MAE : minimized effect K,NaNa,Li

17 T. CharpentierActinet Workshop, September 23th, Al MAS NMR : Mixed Alkali Effect Na/K,Na/Li Analytical model for f(Cq,nq) : Gaussian Isotropic Model (Cjzjek)

18 T. CharpentierActinet Workshop, September 23th, Al MAS NMR : Mixed Alkali Effect Na/K,Na/Li

19 T. CharpentierActinet Workshop, September 23th, Si MAS NMR Na,K Li,Na

20 T. CharpentierActinet Workshop, September 23th, Si RAMAN :  irradiation effects Na/K,Na/Li Na/Li Na/K 50/50 Q2Q2 Q3Q3 Irradiated Pristine MAE: modifier migration blocked Q2Q2 Q3Q3

21 T. CharpentierActinet Workshop, September 23th, Si MAS NMR / RAMAN Q2Q2 Q3Q3 Na/Li : Stable polymerizationLi : Polymerization increase

22 T. CharpentierActinet Workshop, September 23th, Na NMR Localisation of the alkali after the migration processes 1)migration to the surface XPS : No 2) bulk segregation Can NMR provides measurements to detect it ? Static (Non-rotating ) sample approach : Relaxation Time Measurment and SEDOR NMR

23 T. CharpentierActinet Workshop, September 23th, Na NMR : longitudinal relaxation inversion recovery experiment

24 T. CharpentierActinet Workshop, September 23th, Na NMR :  irradiation effects Na/Li

25 T. CharpentierActinet Workshop, September 23th, Na Spin Echo / SEDOR NMR 90 TT E(T) 23Na 7Li E(T) (Hahn Echo): Na-Na dipolar interactions 180 E(T) (SEDOR): Na-Na + Na-Li dipolar interactions 180

26 T. CharpentierActinet Workshop, September 23th, Na Spin Echo / SEDOR NMR

27 T. CharpentierActinet Workshop, September 23th, Na Spin Echo/SEDOR NMR :  irradiation effects Na/Li  : decrease of Na-Li dipolar interactions  Na clusterization ?

28 T. CharpentierActinet Workshop, September 23th, 2005 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 (Au n+ ) (underway) N.Ollier et al, Journal of Physics : Condensed Matter 16 (2004) N.Ollier et al, Journal of Non-Crystalline Solids 341, (2004) 26.

29 T. CharpentierActinet Workshop, September 23th, 2005 Perpectives NMR of active materials : Auto-irradiation effects Special containment (rotor) system See D. Sakellariou

30 T. CharpentierActinet Workshop, September 23th, 2005 Perpectives : Heteronuclear correlation spectrosocopy Static sample NMR can be useful