The influence of IVB elements (Zr, Ti, and Hf) on the glass structure and on the alteration kinetics of soda-lime borosilicate glasses has been studied at various stages of glass leaching corresponding to the initial dissolution rate, rate drop, and residual rate regimes. The effect of these elements on the limiting mechanisms of the glass durability as well as the chemistry of both solution and alteration layer are inter-related, depending on the reaction progress. The effect of IVB elements on the glass structure was investigated using B-11 MAS NMR. The IVB elements are compensated primarily by Na rather than Ca, at the expense of tetracoordinated boron. The addition of HfO2 or ZrO2 decreases the initial dissolution rate in a similar way. Moreover, adding ZrO2 limits the rate drop in saturated media. The initial dissolution rate decrease is less significant when Ti is added, and a quick drop of the dissolution rate is observed up to 4 mol% TiO2. At low IVB element concentration, glasses containing Ti and Zr show different residual rates arising from the precipitation of magadiite (Na2Si14O29 center dot 11H(2)O), at the surface of Ti-bearing glasses. The influence of IVB elements on glass alteration indicates that, unlike Ti, Zr and Hf plays a similar role in the structure of borosilicate glasses. (C) 2010 Elsevier B.V. All rights reserved.
Bergeron, Boris Galoisy, Laurence Jollivet, Patrick Angeli, Frederic Charpentier, Thibault Calas, Georges Gin, Stephane 12th International Conference on the Physics of Non-Crystalline Solids (PNCS12) SEP 06-09, 2009 Foz do Iguacu, BRAZIL Sp. Iss. SI