Structural Study of PbO–B2O3 Glasses by X-ray Diffraction and 11B MAS NMR Techniques

The structure of PbO–B₂O₃ glasses has been investigated in the composition range of 25–80 mol% PbO by using X-ray diffraction and ¹¹B NMR techniques. The well-separated peaks due to Pb–O and Pb–Pb pairs were first observed in the radial distribution function, and peak deconvolution was performed by using a pair function method. The average coordination number of lead atoms was determined to be about 6 in the low-PbO-content region and about 3 in the high-PbO-content region. With an increase of PbO content, the peaks at 0.24 and 0.40 nm shifted to shorter distances, and especially the latter peak drastically increased in intensity in the composition range >50 mol% PbO. It was suggested that PbO is a main glass former in the high-PbO-content region. Based on the results obtained, we propose structural models of lead borate glasses.