11B-MQMAS and 29Si–{11B} Double-Resonance NMR Studies on the Structure of Binary B2O3–SiO2 Glasses

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

“…[6 -9] Indeed binary borosilicate glasses contains only four-coordinated silicon [4] Si (SiO 4 ) and threecoordinated boron [3] B (BO 3 ) as framework unit. In contradiction with earlier models for such glasses predicting high phase separation, 11 B MQMAS NMR [9] and particularly 17 O MQMAS NMR [6] data showed that the mixing between SiO 2 and B 2 O 3 is prominent. Even for glasses with Si/B ratios very different from unity, a large amount of [4] Si-O- [3] B linkages is observed by 17 O NMR elucidating the extent of the chemical disorder.…”

“…For B 6 S 4 statistics of the obtained NMR parameters (it is reminded that a distribution of NMR parameters is obtained from the fit) are reported in Table 7. They compare very well with literature results [8,9] (Table 6) but for which much less constrained analysis were performed essentially fitting 1 D data only. It is worth noticing that the [3] B(ring) peak appears with much lower intensity than expected from the MAS spectrum (Fig.…”

“…This value and these small variations are in excellent agreement with 29 Si MAS NMR measurements. [9] Indeed it was observed that the mean 29 Si isotropic chemical shift remains almost constant at approximately −110 ppm for glass compositions ranging from x = 0.28 to 0.73 in xB 2 O 3 -(1 − x)SiO 2 glass series, a value close to that of vitreous silica (about −112 ppm). Change in the number of coordinated boron (CN B ) i.e.…”

“…[20 -23] Such structural units are also present in binary borosilicate glass as confirmed by 11 B MQMAS NMR. [6,9] In this respect MD simulations can be seen as a way of generating a wide range of local geometries (here characterised by Si-O-Si, Si-O-B and B-O-B bond angles S160 A. Soleilhavoup et al…”

Considerations on the structure and physical properties of B2O3–SiO2 and GeO2–SiO2 glasses

“…Recently van Wüllen and Schwering [7] used various NMR techniques to investigate the structure of B 2 O 3 -SiO 2 glasses. They deduced that these glasses contain two main phases; a SiO 2 -free B 2 O 3 phase and a mixed borosilicate one.…”