Nepheline structural and chemical dependence on melt composition
- Washington State Univ., Pullman, WA (United States)
- Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Nepheline crystallizes upon slow-cooling in some melts concentrated in Na2O and Al2O3, which can result in a residual glass phase of low chemical durability. Nepheline can incorporate many components often found in high-level waste radioactive borosilicate glass, including glass network ions (e.g., Si, Al, Fe), alkali metals (e.g., Cs, K, Na, and possibly Li), alkaline-earth metals (e.g., Ba, Sr, Ca, Mg), and transition metals (e.g., Mn, and possibly Cr, Zn, Ni). When crystallized from melts of different compositions, nepheline chemistry varies as a function of starting glass composition. Five simulated high level nuclear waste borosilicate glasses shown to crystallize large fractions of nepheline on slow cooling, were selected for study. These melts constituted a range of Al2O3, B2O3, CaO, Na2O, K2O, Fe2O3, and SiO2 compositions. Compositional analyses of nepheline crystals in glass by electron probe micro-analysis (EPMA) indicate that boron is unlikely to be present in any significant concentration, if at all, in nepheline. Here, several models are also presented for calculating the fraction of vacancies in the nepheline structure.
- Research Organization:
- Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
- Sponsoring Organization:
- USDOE
- Grant/Contract Number:
- AC05-76RL01830
- OSTI ID:
- 1255389
- Report Number(s):
- PNNL-SA-109528; 830403000
- Journal Information:
- American Mineralogist, Journal Name: American Mineralogist Journal Issue: 2 Vol. 101; ISSN 0003-004X
- Publisher:
- Mineralogical Society of AmericaCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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