A MULTIBODY POTENTIAL TO STUDY THE STRUCTURE OF UNDOPED AND ER3-DOPEDLEAD SILICATE-GLASSES()

Structural features of lead silicate (PbO . SiO2) and Er3+-doped lead silicate glasses were studied using molecular dynamics. Owing to the p artial covalent nature of the Si-O and Pb-O bond, a three-body potenti al was employed throughout the calculation in order to account for bon d directionality. The overall structures of both glasses are in good a greement with experiment. Evidence of a secondary lead network and lea d-lead clustering is also reported: correlating well with previous exp erimental results. In order to obtain a better understanding of the lo cal environment around the dopant Er3+ a compositional study of varyin g dopant concentrations, 0.1, 1.0, 2.5, 5.0 and 10 mol.% was also perf ormed. Results of the simulations indicate that the Er3+ ions tend to be distributed primarily within the lead network and clustering is obs erved at higher dopant concentrations. The average coordination number of the Er3+ ion was found to be 6.3, deviating only slightly with var iations in concentration.