First investigation of the local environment of europium in a strontium phosphate glass using molecular dynamics simulations

Phosphate glasses are characterized by properties distinguished by comparison with those of others such as borates, silicates, and tellurides that can be used in many fields such as optics, electronics, medicine, environmental protection, etc. This study aims to discover the effect of the europium dopant on the structural properties of glasses with 65% P₂O₅ – (35-x) % SrO – x% Eu₃O₂ (where x = 0.5, 1, 1.5, 2 mol at. %) using molecular dynamics simulations. The density of simulated glasses was found to increase from 2.784 to 2.860 g/cm³ according to the gradual increase in the europium content. The Eu-O distances and coordination numbers are found to be in the ranges of 2.18–2.21 Å and 6.59–6.79, respectively. The Sr-O coordination numbers were found to decrease from 7.30 to 6.55 with an increase in the europium content in the phosphate glasses. The coordination of the Eu-Eu pair increases from 0.07 to 0.23 with increasing europium concentration in phosphate glasses, but it remains weak, which is a sign of good solubility of europium in the glass matrix, as expected by experiments and the literature. Studies of the cluster statistics in the simulated glasses demonstrate that most europium atoms are found isolated or in a doublet.