Properties and Structure of Lead Halosilicate Glasses

The glass transformation temperature, thermal expansion coefficient, dc electrical conductivity, and IR transmission have been measured for four series of lead halosilicate glasses of the general composition (65– x )PbO· x PbX₂·35 SiO₂ (X=F, Cl, Br, I). Although results of these and other measurements suggest that the halide ions play similar structural roles in the glass, there appear to be significant differences in physical property behavior between glasses containing F⁻ anions and those containing the other three halide anions. These results are explained by a proposed model incorporating both bridging and nonbridging halide species.