Molecular dynamics simulations of P2O5-Fe2O3-FeO-Na2O glasses

In the paper classical molecular dynamics simulations were used to study the influence of the gradual addition of Na2O on the structure of 55P2O5-30Fe2O3-15FeO glass. Increasing sodium content in the glass causes depolymerization of the glass network and increasing number of non-bridging oxygens in [PO4] tetrahedra. The number of chemical durable P-O-Fe bridges decreases and they are replaced by P-O-Na. This leads to separation of iron cations from [PO4] units and formation of iron oxides clusters. The network of the glass with over 30 mol% of Na2O consists mainly of separated [PO4] tetrahedra and short pyrophosphate chains of [P2O7]4−. The glass structural properties due to sodium content increase are discussed.