First investigation of the effect of strontium oxide on the structure of phosphate glasses using molecular dynamics simulations

Phosphate glasses have features that separate them from other materials such as borates, silicates, and tellurides, and they can be employed in a variety of applications including optics, electronics, medicine, and environmental protection. However, these pure phosphate glasses have low chemical durability, which limits their application. The addition of strontium to the glass considerably improves its durability. The effect of SrO addition in a glass phosphate structure with a formal chemical composition of (100 -x) P2O5 - x SrO (where x = 0, 5, 10, 15... 45 mol. %) was studied using classical molecular dynamics simulations. According to the progressive increase in the SrO content, the density of the simulated glass increased from 2.400 g/cm3 to 2.937 g/cm3, while its molar volume values reduced from 59.143 to 42.449 cm3/mol. The short-range structure of the simulated glasses is described and agrees well with prior experimental and theoretical research. The increased SrO level in the glass resulted in the depolymerization of the phosphate network, according to simulations. Furthermore, we evaluated the aggregation parameter of the Sr-Sr pair, and it was most intense because of the low SrO content, which can lead to the inhomogeneity of the phosphate glass network.