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

Abstract

The structure of PbO-B 2 O 3 glasses has been investigated in the composition range of 25-80 mol% PbO by using X-ray diffraction and 11 B 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-PbOcontent 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.

Solid‐state 207Pb NMR studies of lead‐group 16 and mixed transition‐metal/lead‐group 16 element‐containing materials

“…We were unable to find a crystal structure for the material, but it matches the X-ray powder diffraction pattern of this phase. 15 The spectrum was fitted assuming a single axially symmetric powder pattern. There was no statistically significant improvement in the fitting by assuming an asymmetric powder pattern.…”

Structural and acoustical studies of lead sodium borate glasses

“…Moreover, PbO can enter the glass network both as a network modifier and also as a network former with a formal oxidation state +2. This role depends on the type of bond between lead and oxide [1][2][3][4][5][6].…”

Review of Bi2O3 based glasses for electronics and related applications

“…7; the work of Terashima et al used by Dimitrov 327 seems somewhat at odds with that of Bajaj et al 318 (and previous work cited by the latter 247 ), although the same method (MAS-NMR) was used in both cases and sample fabrication appeared to be well controlled (moderate melting temperatures and noble metal crucibles). Residual impurities 318 could possibly account for some of the discrepancies, as well as thermal history (quenching rate and subsequent annealing), which significantly influences glass properties 376 and even structure (see discussion on 'polyamorphism' 280,318 , the coordination of Pb 2z is somewhat more ordered and much more dependent on x in binary borate glasses, according to XRD and MAS-NMR studies: 397 Coordination number is 6 up to about x525%, then decreases continuously, reaching 3 for x equal or greater than y55%, which is matched by a corresponding decrease of average bond length from y300 down to 233 pm. Pb 2z is therefore roughly present as [PbO 6 ] octahedra and behaves somewhat as a classical modifier at low x, and progressively switches at higher x, well within the vitrification range, to [PbO 3 ] network forming trigonal pyramids (3-PyM), with fewer, stronger Pb-O bonds.…”