¹¹B NMR Spectroscopy of Lead Borate Glasses: Additive Effect of Cerium Oxide

Abstract

Glasses and glass ceramics in the system xCeO 2 · (50 - x)PbO · 50B 2 O 3 (0 ≤ x ≤ 50) have been studied, for the first time, by NMR and FTIR techniques. Effect of CeO 2 substitution with PbO on NMR parameters has been discussed in terms of changing both boron and cerium coordination. The quantitative fraction of four coordinated boron (N 4 ) has been simply determined from 11 B NMR spectroscopy. On the other hand, the fraction of total tetrahedral structural units B 4 (BO 4 + PbO 4 + CeO 4 ) is obtained from FTIR spectral analysis. It is not possible to get the fraction of cerium oxide directly from the applied spectroscopic tools. Therefore, a simple approach is applied, for the first time, to determine CeO 4 fraction by using the different criteria of both 11 B NMR and FTIR spectroscopy. The fraction of B 4 species is equal to N 4 , within the experimental error, of the same glasses in the composition region of up to 10 mol% CeO 2 . On the other hand, there is a clear difference between both N 4 and B 4 values in glasses of higher CeO 2 content ( >10 mol%). The related difference showed a linear increasing trend with increasing the content of CeO 2 in the glass. This was discussed on the bases of structural role of CeO 2 which acts as a glass former in the region >10 mol%, while, at lower concentration, it consumed as a glass modifier.