A molecular dynamics study of lead-bismuth-silicate glasses

We present the results of molecular dynamics (MD) simulations of the structure of ternary lead-bismuth-silicate glasses of compositions xPbO(0.3-x)Bi/sub 1.5/0.7SiO/sub 2/, x=0.06, 0.15, 0.24, and their totally reduced forms, i.e. xPb(0.3-x)Bi0.7SiO/sub 2/, x=0.06, 0.15, 0.24 systems. The simulations have been performed in the microcanonical (NVE) ensemble, using two-body interaction potentials. The results can be summarized as follows. With increasing PbO content in unreduced xPbO(0.3-x)Bi/sub 1.5/0.7SiO/sub 2/ glasses, the Pb-O and Bi-O first pair distribution function (PDF) peaks become sharper, and the fraction of strained 2 and 3 member Si-O-Si-O- rings decreases significantly. In the case of reduced xPb(0.3-x)Bi0.7SiO/sub 2/ glasses, similarly as in reduced binary lead-silicate and bismuth-silicate glasses, a strong tendency to agglomeration of neutral atoms occurs. The metallic phase is composed of Pb-Bi alloy. The agglomeration tendency increases with increasing Pb content.