Abstract
The short, medium, and long range structures of lead silicate glasses are investigated by XRD and NRD analyses, XPS, Raman spectroscopy, and the Pb2+ leaching test over a wide composition region. The edge shared trigonal bipyramids, Pb2O4 unit, are considered to be the most plausible basic structural unit of lead ions in the glasses over the entire range of compositions. The diffusion coefficient of Pb2+ was drastically increased above the medium lead compositions (45~50mol% PbO), indicating changes in the medium or longer range structure. That is, it is suggested that the Pb2O4 units tend to connect with each other to form Pb2+ diffusion paths in the glasses over these compositions. Based on the results obtained, we proposed a comprehensive structural model of lead silicate glasses.
