Ab Initio Molecular Dynamics Insights Into the Atomic‐Scale Structure in PbO–B ₂ O ₃ –ZnO Glasses Containing PbBiO ₂ I

ABSTRACT We present an ab initio molecular dynamics (AIMD) study of PbO–B 2 O 3 –ZnO glasses relevant to iodine immobilization in nuclear waste management. Three compositions were investigated: binary 2PbO–B 2 O 3 (PB), ternary 65PbO–5ZnO–30 (PZB), and an iodine‐bearing glass based on 65PbO–5ZnO–30 with added 3 (PZBI). The AIMD‐derived structures reproduce the experimental X‐ray and neutron structure factors, demonstrating that the simulated glasses accurately capture the local atomic environments. Analysis of coordination statistics and pair distribution functions clarifies the respective roles of PbO, , and ZnO in shaping the glass network and the influence of Bi and I. Lead forms highly asymmetric polyhedra with average coordination numbers of approximately 6.6–6.9, which remain largely unchanged upon the addition of ZnO and , although the second coordination sphere around Pb is perturbed. Zinc predominantly adopts tetrahedral coordination in PZB, whereas the introduction of in PZBI generates a significant fraction of three‐coordinated Zn, indicating that iodine‐bearing species modify the local coordination of Znq Iodine shows weak correlations with O, B, and Pb, but distinct first‐neighbor interactions with Bi and Zn, evidencing its stabilization through Bi–I and Pb–I structural motifs within the glass network. These atomistic insights into the local and intermediate‐range structures of PbO‐rich borate glasses provide a fundamental understanding of iodine incorporation and retention mechanisms, and offer guidance for the rational design of advanced glass waste forms for volatile radionuclides.