Atomic environments in binary lead silicate and ternary alkali lead silicate glasses

High resolution x-ray photoelectron spectroscopy, (HRXPS) has been used to obtain binding energy, information for the Pb 4f, 4d and 5d, Si 2p, Na Is, Li Is and O1s photoelectron peaks, along with the 0 KLL Auger transitions and valence band spectra, in glasses of general formula xPbO (1-x)SiO2 (0less than or equal toxless than or equal to0.67) and xPbO (0.3-x)R2O 0.7SiO(2) (0less than or equal toxless than or equal to0.3 R=Na, Li). The binding energy changes with composition are used to infer polarising powers for the Pb2+, Li+ and Na+ ions and, whilst these are consistent with simple cation potentials for Li+ and Na+, this is not true for Pb 21 which appears to be more highly electron donating. This suggests that the inert pair of electrons are involved in enhancing charge density in the Pb-O bonds and hence confer a degree of network intermediate behaviour 077 PbO in lead silicate glasses. The intensity distribution in the 0 Is photoelectron peaks from the lead silicate binary glasses can be explained by, disproportionation of some Pb-O-Si species to give Pb-O-Pb and Si-O-Si. The Pb-O-Pb links are sufficiently covalent to maintain the network which would not be possible with R+-O-R+ links. There is no evidence for 3-coordinated oxygens from the 0 Is data. Physical property data for the binary glasses are consistent with a reduced modifier behaviour of PbO and values for the ternaries generally follow, a linear interpolation between end members