Structural features and optical-luminescent properties of the Pb-containing germanate and silicate oxyfluoride glasses

The XRD, IR transmission, EPR, optical absorption, luminescence spectra and decay kinetics in new un-doped 0.5PbO-0.3GeO2-0.2AlF3 and 0.53PbO-0.226SiO2-0.244AlF3 glasses were investigated. The XRD patterns were analysed in order to obtain the radial distribution functions and define the average interatomic distances and coordination numbers in the network of investigated glasses. The IR transmission, EPR, and UV-vis optical absorption spectra of the studied glasses were interpreted. Optical band gap and Urbach energy were obtained from analysis of the fundamental absorption edge. Under UV photoexcitation the 0.5PbO-0.3GeO2-0.2AlF3 and 0.53PbO-0.226SiO2-0.244AlF3 glasses demonstrate broad emission band at 493 nm and 499 nm, respectively. Fast (band-to-band recombination) and slow (recombination with a contribution of defects levels) mechanisms of intrinsic luminescence have been proposed from a detailed analysis of luminescence spectra and decay kinetics curves. The CIE chromaticity diagram shows a variation in emission colour of studied glasses with the change in their composition.