Pb2+ environment in lead silicate glasses probed by Pb-L-III edge XAFS andPb-207 NMR

The local structural environment of lead (Pb) atoms in lead silicate glasse s has been studied by two complementary spectroscopic techniques: Pb-L-III edge X-ray absorption fine structure (XAFS) and Pb-207 solid State nuclear magnetic resonance (NMR). XAFS results have been obtained with two kinds of experimental devices: a synchrotron radiation source and a laboratory spec trometer. The weak photon flux is then compensated by a higher stability of the source and a longer acquisition time. The experiments were carried out on selected compositions of lead silicate glasses in which we observed PbO 3 and PbO4 pyramidal units with short Pb-O bond lengths typical of a covale nt bonding state. (C) 1999 Elsevier Science B.V. All rights reserved.