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A Solid State NMR Study of a Mixed Alkali Aluminoborosilicate Glass Structure and

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 L aboratoire de S tructure et D ynamique par R ésonance M agnétique

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A Solid State NMR Study of a Mixed Alkali Aluminoborosilicate Glass Structure and

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

  2. Vitrified waste (CSD-V) 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 Actinet 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) 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 Actinet Workshop, September 23th, 2005

  4. -8 Na/Li Na/K -9 -1 m) s ( W. -10 Log -11 -12 0 0.2 0.4 0.6 0.8 1 mol % (Na O)/(Na O+Z) 2 2 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 ? Actinet Workshop, September 23th, 2005

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

  6. 11B (I=3/2) MAS NMR Actinet Workshop, September 23th, 2005

  7. 11B MAS / MQMAS NMR MAS (1d) MQMAS (2d) Actinet Workshop, September 23th, 2005

  8. 11B MQMAS NMR BO3 2 sites BO4 2 sites Actinet Workshop, September 23th, 2005

  9. 11B MAS NMR Actinet Workshop, September 23th, 2005

  10. 11B MAS NMR : Mixed Alkali Effect Actinet Workshop, September 23th, 2005

  11. 11B MAS NMR : Mixed Alkali Effect Na/K : BO3/BO4 maximum Na/Li : BO3/BO4 minimum Non-linear variation of the BO3/BO4 ratio Actinet Workshop, September 23th, 2005

  12. 11B MAS NMR :  irradiation effects Na/Li BO4 to BO3 conversion Actinet Workshop, September 23th, 2005

  13. 11B MAS NMR :  irradiation effects Na/K BO4 to BO4/BO3 conversion No conversion Actinet Workshop, September 23th, 2005

  14. 27Al MAS NMR Actinet Workshop, September 23th, 2005

  15. 27Al MAS NMR : Mixed Alkali Effect AlO4- : Na+ preferential charge compensator ? Actinet Workshop, September 23th, 2005

  16. 27Al MAS NMR :  irradiation effects Na/K,Na/Li K,Na Na,Li Cq increases (site distortion increase). MAE : minimized effect Actinet 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) Actinet Workshop, September 23th, 2005

  18. 27Al MAS NMR : Mixed Alkali Effect Na/K,Na/Li Actinet Workshop, September 23th, 2005

  19. 29Si MAS NMR Na,K Li,Na Actinet Workshop, September 23th, 2005

  20. Q2 Q3 29Si RAMAN :  irradiation effects Na/K,Na/Li Na/K Q3 Q2 Irradiated Pristine 50/50 Na/Li MAE: modifier migration blocked Actinet Workshop, September 23th, 2005

  21. 29Si MAS NMR / RAMAN Na/Li : Stable polymerization Li : Polymerization increase Q2 Q3 Actinet Workshop, September 23th, 2005

  22. 23Na NMR Localisation of the alkali after the migration processes • 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 Actinet Workshop, September 23th, 2005

  23. inversion recovery experiment 180 90 23Na NMR : longitudinal relaxation Actinet Workshop, September 23th, 2005

  24. 23Na NMR :  irradiation effects Na/Li Actinet Workshop, September 23th, 2005

  25. 180 E(T) (SEDOR): Na-Na + Na-Li dipolar interactions 23Na Spin Echo / SEDOR NMR T T E(T) 90 180 23Na 7Li E(T) (Hahn Echo): Na-Na dipolar interactions Actinet Workshop, September 23th, 2005

  26. 23Na Spin Echo / SEDOR NMR Actinet Workshop, September 23th, 2005

  27. 23Na Spin Echo/SEDOR NMR :  irradiation effects Na/Li  : decrease ofNa-Li dipolar interactions Na clusterization ? Actinet 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. Actinet Workshop, September 23th, 2005

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

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

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