On the constitution of silicate groupings in binary lead silicate glasses

Direct chemical methods have been used to determine the type and the percentage of silicate groupings present in binary lead silicate glasses within the composition range 4PbO · SiO 2 PbO · SiO 2 . The results obtained indicate that the constitution and the relative amounts of various silicate groupings change with the changing total amount of SiO 2 in the glass. Glasses containing small amounts of SiO 2 are characterized by the presence of few low-molecular silicate units; increasing the percentage of SiO 2 promotes the formation of higher polymerized silicate groupings. The results are discussed with regard to stoichiometry, and are consistent with Hägg's concept of glassiness.