Structural and optical properties of WO3–ZnO–PbO–B2O3 glasses

Glass samples of compositions 20PbO–80B2O3 and xWO3—(20−x) ZnO–20PbO–60B2O3 with x varying from 0% to 10% mole fraction are prepared by the melt quench technique. Decrease in the band gap from 2.86 to 2.16 eV for ZnO–PbO–B2O3 glasses with an increase in the WO3 content has been observed and discussed. The FTIR spectral studies have pointed out the conversion of structural units of BO3 to BO4 and WO4 to WO6 with the presence of W–O–W vibration of tungsten and incorporation of ZnO4 structural units of zinc in these glasses. The increase in density from 2.75 to 4.03 gcm−3 for ZnO–PbO–B2O3 glasses is observed with an increase in WO3 content. Due to the formation of WO6, WO4 and BO4 units, changes in the atomic structure with WO3 composition are observed and discussed.