Glass - Back to the Future!

Presenting Author:
Elise Régnier

article posted 04 April 2016

Elise Régnier is a research engineer at the French alternative energies and atomic energy commission (CEA) where she works on glass for nuclear waste conditioning and more specifically on crystallization phenomena in glasses. Before joining the CEA, Elise worked within Alcatel Optical Fiber / Draka on telecommunication optical fibers, on the relation between silica material properties and fiber attenuation. In 2004, she received her PhD in materials science, studying the residual absorption losses around 1550 nm in silica optical fibers.

Ag-solubility in borosilicate nuclear glass

E. Régnier*, D. Perret, N. Massoni, A. Laplace, S. Schuller, A. Issoire, V. Lemaitre, C. Vallat, V. Ansault, I. Bardez-Giboire
CEA, DEN, DTCD/SECM - Marcoule, F-30207 Bagnols-sur-Cèze, France

Solubility of silver in nuclear borosilicate glass has already been studied, as high-silver content waste streams resulting from the conversion of plutonium to MOX (mixed oxide) nuclear fuel may be vitrified [1]. Ag-solubility in glass melts strongly varies from a glass to another. Indeed, as reported by [1] [2], Ag-solubility is highly dependent on several parameters such as glass composition, temperature and redox state. The present study concerns two types of sodium-borosilicate glass containing 0.75 wt% of Ag2O. The first one is a simulated high-level nuclear glass, the other one is a 12 oxides glass. In both cases, based on thermodynamic considerations [3], silver is expected in Ag0 form. However, depending on the studied case, it appears that silver is either totally or only partially dissolved in the glass network. In the first case, SEM pictures reveal an homogeneous glass material whereas, in the second case, Ag-particles of a few 100 nm of diameter are clearly visible (figure 1). In order to better understand the incorporation of silver ions within borosilicate glass matrices, sensitivity to specific parameters as melting temperature and glass composition have been tested, and SEM, XRD, TEM, microprobe, XANES and Mössbauer investigations have been conducted. The determining role of Fe2O3, already reported by [2], has been observed, as well as the interaction of Ag with other noble metals entering in the nuclear glass composition.

Figure 1: SEM pictures of 2 borosilicate glasses containing 0.75 wt% of Ag2O fully dissolved (left) and partially dissolved (right) in the glass network.

[1] : D. A. McKeown, H. Gan, I. L. Pegg “Silver valence and local environments in borosilicate and calcium aluminoborate waste glasses as determined from X-ray absorption spectroscopy” Journal of Non-Crystalline Solids 351, pp. 3826–3833 (2005).
[2] : X.C. Yang, M. Dubiel, S. Brunsch, H. Hofmeister , “X-ray absorption spectroscopy analysis of formation and structure of Ag nanoparticles in soda-lime silicate glass” Journal of Non-Crystalline Solids 328, pp. 123–136 (2003).
[3] : H.D. Schreiber, T.R. Harville, G.N. Damron “Redox-controlled solubility of Palladium in a borosilicate glass melt”, J. Am. Ceram. Soc., 73(5), pp. 1435-1437 (1990).