Interaction of lead silicate glasses with hydrogen under heating

The mechanisms of formation of the surface layer of lead silicate glasses during their interaction with hydrogen under heating were studied by X-ray photoelectron spectroscopy. The thermostimulated change in the composition of an outer surface layer (with a thickness in the order of 100 Å ) goes in the direction of the minima in the liquidus line of the diagram of states for PbO–SiO2. The reduction process follows the scheme[PbO3]δ−→Pbmod−O→[PbO]ion→Pb0,where [PbO3]δ− is the network-forming lead (glass former), Pbmod the modifier lead, [PbO]ion the intermediate lead–oxygen compound with a more ionic character of the Pb–O bond.