Raman scattering spectra and optical properties of tellurite glasses and crystalline phases containing PbO and CdO

The glass forming region in the system of PbO-CdO-TeO 2 was determined and the structure of glasses and crystalline phases were examined by Raman scattering spectra. The wide glass formation was obtained in the range (mol%) of 10-40 PbO, 0-30 CdO and 40-90 TeO 2 . The melt quenched sample of 50 PbO.50TeO 2 is not amorphous but the transparency of the crystalline sample is excellent. The formation of the crystalline phases of CdTe 2 O 5 and CdTeO 3 were confirmed in the melt quenched samples without or with low PbO content and the features of their Raman spectra were clarified. It was demonstrated from the Raman spectra that the number of Te-O-Te linkages in the glasses and thus the network connectivity decreases with increasing Pb O and CdO contents. The glasses heat treated at 320°C (below the crystallisation temperature 364°C) in nitrogen or (93%Ar+7%H 2 ) atmosphere became shiny black slightly with keeping a good transparency and it was found that an unknown crystalline phase (not CdTe or Cd 2 PbO 4 semiconductor) was formed at the surface.