resumo
A series of sodium borosilicate glasses were synthesized with KReO4 or Re2O7, to 10,000ppm (1mass%) target Re, to assess effects of large concentrations of rhenium on glass structure and fto estimate solubility of 99Tc, a radioactive component in low active waste nuclear glasses. Rhenium was used as a surrogate for 99Tc for laboratory testing, due to similarities in chemistry, ionic size, and redox. Magic angle spinning nuclear magnetic resonance, Fourier transform infrared spectroscopy, and Raman spectroscopy were performed to characterize the glasses. Si was coordinated in Q2 and Q3 units, Al was four-coordinated, and B was mostly three-coordinated. The rhenium additions did not have significant effects on the glass structure up to approximately 3000ppm Re by mass, the maximum concentration that remained dissolved in glass. Rhenium likely exists in isolated ReO4 anions in the interstices of the glass network, as evidenced by polarized Raman spectrum of the Re glass in the absence of sulfate. Analogous to SO4 2 in similar glasses, ReO4 is a network modifier and above solubility forms alkali salt phases on the surface and in the bulk. Comparisons of phase separation and crystallization in MoO4 2 containing borosilicate glasses can also be made to ReO4 containing glasses.
palavras-chave
NUCLEAR-MAGNETIC-RESONANCE; WASTE GLASSES; MAS-NMR; ALUMINOSILICATE GLASSES; SILICATE-GLASSES; RAMAN; SPECTROSCOPY; SOLUBILITY; TECHNETIUM; SPECTRA
categoria
Materials Science
autores
Goel, A; McCloy, JS; Windisch, CF; Riley, BJ; Schweiger, MJ; Rodriguez, CP; Ferreira, JMF
nossos autores
José Maria da Fonte Ferreira
Professor(a) Jubilado(a)agradecimentos
This work was supported by the Department of Energy's Waste Treatment & Immobilization Plant Federal Project Engineering Division under the direction of Dr. Albert A. Kruger. The authors thank Dr. Dong-Sang Kim and two anonymous reviewers for their valuable comments on the paper. Thanks to Dr. John Vienna for providing the background context for the Hanford site. Pacific Northwest National Laboratory is operated by Battelle Memorial Institute for the U.S. Department of Energy under contract DE-AC05-76RL01830.