Glass structure and crystallization in boro-alumino-silicate glasses containing rare earth and transition metal cations:
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MRS Advances © 2019 Materials Research Society DOI: 10.1557/adv.2019.99
Glass structure and crystallization in boro-aluminosilicate glasses containing rare earth and transition metal cations: a US-UK collaborative program John S. McCloy,1,2 José Marcial,1 Deepak Patil,1 Muad Saleh,1 Mostafa Ahmadzadeh,1 Hua Chen,1,6 Jarrod V. Crum,2 Brian J. Riley,1,2 Hrishikesh Kamat,3 Antoine Bréhault,3 Ashutosh Goel,3 Kristian E. Barnsley,4 John V. Hanna4 Prashant Rajbhandari,5 Claire L. Corkhill,5 Russell J. Hand,5 Neil C. Hyatt5
1
Washington State University, Pullman, WA, USA
2
Pacific Northwest National Laboratory, Richland, WA, USA
3
Rutgers University, New Jersey, USA
4
University of Warwick, Coventry, UK
5
University of Sheffield, Sheffield, UK
6
Inner Mongolia University of Science and Technology, China
1029
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ABSTRACT
Nuclear wastes generated from reprocessing of used nuclear fuel tend to contain a large fraction of rare earth (RE, e.g., Nd3+), transition (TM, e.g., Mo6+, Zr4+), alkali (A, e.g., Cs+), and alkaline earth cations (AE, e.g., Ba2+, Sr2+). Various strategies have been considered for immobilizing such waste streams, varying from nominally crystal-free glass to glass-ceramic to multi-phase ceramic waste forms. For glass and glass-ceramic waste forms, the added glass-forming system is generally alkali-alkaline earth-aluminoborosilicate (i.e., Na-Ca-Al-BSi oxide). In a US-UK collaborative project, summarized here, we investigated the glass structure and crystallization dependence on compositional changes in simulated nuclear waste glasses and glass-ceramics. Compositions ranged in complexity from five – to – eight oxides. Specifically, the roles of Mo and rare earths are investigated, since a proposed glassceramic waste form contains crystalline phases such as powellite [(AE,A,RE)MoO 4] and oxyapatite [(RE,AE,A)10Si6O26], and the precipitation of molybdenum phases is known to be affected by the rare earth concentration in the glass. Additionally, the effects of other chemical additions have been systematically investigated, including Zr, Ru, P, and Ti. A series of studies were also undertaken to ascertain the effect of the RE size on glass structure and on partitioning to crystal phases, investigating similarities and differences in glasses containing single RE oxides of Sc, Y, La, Ce, Nd, Sm, Er, Yb, or Lu. Finally, the effect of charge compensation was investigated by considering not only the commonly assessed peralkaline glass but also metaluminous and peraluminous compositions. Glass structure and crystallization studies were conducted by spectroscopic methods (i.e., Raman, X-ray absorption, nuclear magnetic resonance (NMR), optical absorption, photoluminescence, photoluminescence excitation, X-ray photoelectron spectroscopy), microscopy (i.e., scanning electr
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