Lone-pair distribution and plumbite network formation in high lead silicate glass, 80PbO·20SiO2

Oliver L. G. Alderman; Alex C. Hannon; Diane Holland; Steve Feller; Gloria Lehr; Adam J. Vitale; Uwe Hoppe; Martin v. Zimmerman; Anke Watenphul

doi:10.1039/C3CP51348C

Lone-pair distribution and plumbite network formation in high lead silicate glass, 80PbO·20SiO₂†

Oliver L. G. Alderman,*^a Alex C. Hannon,*^b Diane Holland,^a Steve Feller,^c Gloria Lehr,^c Adam J. Vitale,^c Uwe Hoppe,^d Martin v. Zimmerman^e and Anke Watenphul^e

Author affiliations

* Corresponding authors

^a Department of Physics, University of Warwick, UK
E-mail: oalderman@gmail.com

^b ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 0QX, UK
E-mail: alex.hannon@stfc.ac.uk

^c Physics Department, Coe College, Cedar Rapids, IA 52402, USA

^d Institut für Physik, Universität Rostock, 18051 Rostock, Germany

^e Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, D-22603 Hamburg, Germany

Abstract

For the first time a detailed structural model has been determined which shows how the lone-pairs of electrons are arranged relative to each other in a glass network containing lone-pair cations. High energy X-ray and neutron diffraction patterns of a very high lead content silicate glass (80PbO·20SiO₂) have been used to build three-dimensional models using empirical potential structure refinement. Coordination number and bond angle distributions reveal structural similarity to crystalline Pb₁₁Si₃O₁₇ and α- and β-PbO, and therefore strong evidence for a plumbite glass network built from pyramidal [PbO_m] polyhedra (m ∼ 3–4), with stereochemically active lone-pairs, although with greater disorder in the first coordination shell of lead compared to the first coordination shell of silicon. The oxygen atoms are coordinated predominantly to four cations. Explicit introduction of lone-pair entities into some models leads to modification of the local Pb environment, whilst still allowing for reproduction of the measured diffraction patterns, thus demonstrating the non-uniqueness of the solutions. Nonetheless, the models share many features with crystalline Pb₁₁Si₃O₁₇, including the O–Pb–O bond angle distribution, which is more highly structured than reported for lower Pb content glasses using reverse Monte Carlo techniques. The lone-pair separation of 2.85 Å in the model glasses compares favourably with that estimated in α-PbO as 2.88 Å, and these lone-pairs organise to create voids in the glass, just as they create channels in Pb₁₁Si₃O₁₇ and interlayer spaces in the PbO polymorphs.

This article is part of the themed collection: Hard X-rays and the Frontiers of Materials Chemistry

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Article information

DOI: https://doi.org/10.1039/C3CP51348C
Article type: Paper
Submitted: 29 Mar 2013
Accepted: 29 Apr 2013
First published: 29 Apr 2013

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Phys. Chem. Chem. Phys., 2013,15, 8506-8519

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Lone-pair distribution and plumbite network formation in high lead silicate glass, 80PbO·20SiO₂

O. L. G. Alderman, A. C. Hannon, D. Holland, S. Feller, G. Lehr, A. J. Vitale, U. Hoppe, M. v. Zimmerman and A. Watenphul, Phys. Chem. Chem. Phys., 2013, 15, 8506 DOI: 10.1039/C3CP51348C

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