Dresden 2026 – wissenschaftliches Programm
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FM: Fachverband Funktionsmaterialien
FM 2: Energy Materials
FM 2.3: Vortrag
Montag, 9. März 2026, 10:00–10:15, BEY/0138
The Role of Lone Pairs in Fast Oxide Ion Conduction in Bi0.8Pr0.2O1.5 — •Marcin Kryński — Warsaw University of Technology
Elucidating the microscopic processes that enable rapid oxide-ion transport is key to advancing solid electrolyte design. In this study, we integrate total neutron scattering with reverse Monte Carlo modelling and ab initio molecular dynamics to dissect the structural and electronic mechanisms underlying a pronounced conductivity increase observed across the order/disorder phase transition. Our results reveal that this transition is driven not by changes in the cation framework, but by a collective reorganization of oxide ions and local coordination environments. Specifically, oxide ions shift from the edges of fluorite-like blocks into the van der Waals gap, where they gain access to extended, predominantly two-dimensional diffusion pathways. Concurrently, BiO4 units undergo a subtle yet systematic reorientation linked to the stereochemical activity of Bi3+ lone pairs. Although the local coordination of Bi remains largely preserved, the orientation of these lone pairs evolves in tandem with the redistribution of oxide ions, suggesting a dynamic coupling reminiscent of a paddle-wheel-type mechanism. This interplay between lone-pair-driven asymmetry and anion mobility provides a unified mechanistic picture of how structural flexibility and electronic degrees of freedom cooperate to enhance high-temperature oxide-ion transport. The insights gained here establish general principles for designing fast-ion conductors in systems where active lone pairs play an essential role.
Keywords: ab initio; solid electrolytes; diffusion