TITLE:
11B NMR Spectroscopy of Lead Borate Glasses: Additive Effect of Cerium Oxide
AUTHORS:
Gomaa El-Damrawi, Fawzia Gharghar, Rawia Ramadan, Mohamed Aboelez
KEYWORDS:
New Approach, Cerium Oxide, Boron Fraction
JOURNAL NAME:
New Journal of Glass and Ceramics,
Vol.6 No.4,
October
11,
2016
ABSTRACT: Glasses
and glass ceramics in the system xCeO2·(50-x)PbO·50B2O3 (0 ≤ x ≤ 50) have been
studied, for the first time, by NMR and FTIR techniques. Effect of CeO2 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 (N4) has been simply determined from 11B
NMR spectroscopy. On the other hand, the fraction of total tetrahedral
structural units B4 (BO4 + PbO4 + CeO4) 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 CeO4 fraction by using the different
criteria of both 11B NMR and FTIR spectroscopy. The fraction of B4 species is equal to N4, within the experimental error, of the same
glasses in the composition region of up to 10 mol% CeO2. On the
other hand, there is a clear difference between both N4 and B4 values in glasses of higher CeO2 content (>10 mol%). The related difference showed a linear increasing trend with
increasing the content of CeO2 in the glass. This was discussed on
the bases of structural role of CeO2 which acts as a glass former in
the region >10 mol%, while,
at lower concentration, it consumed as a glass modifier.