Influence of zirconium on the structure of pristine and leached soda-lime borosilicate glasses: Towards a quantitative approach by 17O MQMAS NMR

Abstract

a b s t r a c t 17 O MQMAS NMR was used to characterize the influence of zirconium on the structural organization of soda-lime borosilicate glasses. A new method of quantitative analysis of the 17 O MQMAS spectra is presented, by a direct fit of the two-dimensional MQMAS spectrum which provides the resolution of all the structural groups in glasses containing up to five oxides. Additional data were also obtained from the quantitative deconvolution of the 11 B MAS NMR spectra, with the help of the direct fit of MQMAS data as well. Excess of non-bridging oxygen is clearly identified in these glasses. Sixfolded zirconium is preferentially compensated rather than the tetrahedral boron and calcium only partially compensate the tetrahedral boron. Alteration gels arising from glass leaching were probed by oxygen-17 supplied by the alteration solution. Most of the zirconium is inserted in the silicate network forming Si-O-Zr bonds with the same configuration in the glass and in the gel. During leaching, calcium clearly remains in the alteration gel, either near non-bridging oxygen or as a zirconium charge compensator. This quantitative approach applied to 17 O MQMAS spectra demonstrates its potential for investigating the structure of increasingly complex glass and gel compositions.

Elemental and isotopic (29Si and 18O) tracing of glass alteration mechanisms

“…Galoisy et al (1999) and Angeli et al (2008) showed that Zr is 6-fold coordinated and conserves a similar local structural role in the gel. Angeli et al (2008) also observed that Ca remains in the gel as a Zr charge compensator. Ca, Sr, Si, Al, and Ba are also precipitated in the secondary phases, mainly in phyllosilicates and in phosphates for calcium .…”

“…Zr is mainly present in the gel layer due to its very low solubility (Arab et al, 2008). Galoisy et al (1999) and Angeli et al (2008) showed that Zr is 6-fold coordinated and conserves a similar local structural role in the gel. Angeli et al (2008) also observed that Ca remains in the gel as a Zr charge compensator.…”

“…The texture of the gel is porous (Ledieu et al, 2004;Rebiscoul et al, 2004;Cailleteau et al, 2008) and its structure has been investigated by high-resolution solid-state Nuclear Magnetic Resonance (NMR) for probing the glass evolution during alteration (transformation into gel) (e.g. Bunker et al, 1986Bunker et al, , 1988Angeli et al, 2001Angeli et al, , 2006Angeli et al, , 2008Tsomaia et al, 2003;Ledieu et al, 2004). The glass composition influences the gel structure and its retention properties.…”

Contribution of first-principles calculations to multinuclear NMR analysis of borosilicate glasses

“…For 1 D spectra typically 128 FIDs were accumulated for 29 Si and 11 B with a recycle delay of 16 and 2 s respectively. 11 B MQMAS experiments were performed using the RIACT-shifted echo pulse sequence [51 -53] with parameters given in Refs [54,55]. This pulse sequence was found to provide a much better sensitivity for observing boron-11 NMR signal in BO 3 units than the Z-filter pulse sequence.…”

Aqueous alteration of five-oxide silicate glasses: Experimental approach and Monte Carlo modeling

“…Recent results suggest that the [ZrO 6 ] 2À groups are mainly compensated by calcium in the alteration layer [17]. We therefore decided to compensate the zirconium atoms preferentially by calcium atoms.…”