The Relationship between Structural and Optical Properties of GeO2-PbO Glasses

The structural and optical characterization of bulk GeO2-PbO glasses was the goal of this study. In this regard, six different (100-x)GeO2‌-xPbO (15<x<45) glasses were prepared by conventional melt quenching technique between two steel sheets. The produced samples were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) and UV-Vis spectroscopy. The fundamental absorption edge of prepared glasses was analyzed in terms of the theory proposed by Davis and Mott. According to achieved results, fully amorphous phase can easily form in GeO2-PbO system up to 45 mole % of PbO. The optical characteristic of GeO2-PbO glasses showed an anomalous behavior at 25 mole % of PbO for the transmittance, absorption edge, optical energy gap and Urbach energy. This behavior is related to the conversion of GeO4 tetrahedra to GeO6 octahedra and increasing the number of non-bridging oxygens upon increasing the PbO content up to 25 mole %.