ELECTRONIC BAND-STRUCTURE AND OPTICAL-PROPERTIES OF OXIDE GLASSES .2. LEAD SILICATES

Results of a combined experimental and theoretical study of glasses formed from PbO and SiO2 are presented. It is found that, with increasing PbO content, the optical absorption shifts towards the visible and increases in intensity in the near- U.V. region. These new absorptions are responsible for the high refractive indices of the glasses in the visible region. Electronic-band-structure and density-of-states calculations predict the positions and intensities of absorption satisfactorily and show that the low-energy hands are derived from Pb 68→Pb 6p transitions together with some charge transfer from O 2p→Pb 6p states. The effective number of electrons involved in determining the absorption characteristics is shown to be close to the number of valence electrons available. © 1979 Taylor & Francis Ltd.