Structural investigation and properties of Sb2O3-PbO-B2O3 glasses

XRD patterns indicate that the glasses xSb2O3⋅(40 − x)PbO⋅60B2O3⋅0.5CuO and xSb2O3⋅40PbO⋅(60 − x)B2O3⋅0.5CuO have amorphous structure for 0 ≤ x ≤ 40 mol%. The fraction (N4) of four coordinated boron atoms of both series decreases with increasing Sb2O3 content. The density decreases in the first series, whereas it increases in the second one. The contribution to N4 from PbO and Sb2O3 in each series could be separated. Sb2O3 contributes negatively to N4 in the second series, which is attributed to association of Sb2O3 and PbO forming Pb2Sb2O7 phase. Calculated densities agree well with the experimental data of the first series. Calculated densities could be obtained from the concentration of various structural units in glasses, as predicted from N4 data. Glasses in the second series have strong tendency to crystallization when heat treated. This tendency is not observed in the first series. These effects are explained by considering the abundance of B2O3 in glass.