Revealing the Structure-Property Relationships of Nd2O3-Containing Alkali Iron Phosphate Glasses from Molecular Dynamics Simulations

J Kalahe and XA Lu and K Miller and M Peterson and BJ Riley and JD Vienna and JE Saal and JC Du, CHEMISTRY OF MATERIALS, 37, 8595-8613 (2025).

DOI: 10.1021/acs.chemmater.5c01505

The atomic structure and structure-property relationships of Nd2O3-containing potassium iron phosphate glasses were investigated by using molecular dynamics (MD) simulations based on nulcear waste glass compositions designed with artificial intellegence (AI) and machine learning (ML) approaches. The results show that Nd3+ ions act as modifiers, with an average Nd3+-O bond distance of 2.35 & Aring; and a coordination number of approximately 6. Nd3+ ions were found to be preferentially associated with phosphate anionic units such as PO43- and P2O74-, leading to the formation of nonbridging oxygens, while K+ ions primarily compensate for the negatively charged FeO4 - units. Clustering of Nd3+ ions was observed in the simulated glasses, with a decrease in homogeneous dispersion as the Nd2O3 concentration increased from 5 to 10 mol %. Additionally, increasing the P2O5 content increases the fraction of isolated Nd3+ ions. The addition of Nd2O3 notably affected the glass structures and led to significant changes in the mechanical properties and glass transition temperature values. The results demonstrate that physics based modeling method such as MD simulations with reliable interatomic potentials can be a valuable tool for composition optimization based on AI/ML design and for elucidating the complex structures and structure-property relationships of rare- earth-ion-containing phosphate glasses, a materials class with applications in critical fields such as photonics and nuclear waste disposal.

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