Experimental characterizations and molecular dynamics simulations of the structures of lead aluminosilicate glasses

Exploring the atomic-level structure of lead aluminosilicate glass is extremely important for improving the performance of the related products such as optical devices and semiconductor packages. In this work, we developed a set of potential parameters for the lead aluminosilicate ternary system. Raman and X-ray photoelectron spectroscopy were used to obtain structural information of the glass, and the results were compared with those of MD simulations to elucidate the structural details of a series of lead aluminosilicate glasses. It is found that both silicon and aluminum assume four-fold coordination and form the backbone of the network structures. At a low PbO content, Pb2+ plays the role of both charge compensators and network modifiers. When the PbO content exceeds 30mol%, some Pb2+ ions will be incorporated into the network that leads to rearranging of the network structures. After entering the glass network, Pb2+ ions first break the Al-O-Si linkages to form the Si-O-Pb and Al-O-Pb bonds. Then the remaining Pb2+ ions preferentially form the Pb-O-Pb bonds. It is found in the Raman spectra and X-ray photoelectron spectra that the number of lead ions in ionic state is decreasing and that in covalent state is increasing with the increase of PbO content, confirming the results from MD simulations. In addition, the network formers first shift to a high degree of polymerization and then gradually depolymerize, which is consistent with the results in MD simulations.