Regensburg 2025 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 35: Transport in Materials: Diffusion, Charge or Heat Conduction
MM 35.4: Talk
Friday, March 21, 2025, 11:00–11:15, H22
Diffusion behavior of Li ions in crystalline and amorphous Li-Zr-O and Li-Nb-O phases — •Daniel Mutter1, Diego A. Pantano2, Christian Elsässer1, and Daniel F. Urban1 — 1Fraunhofer IWM, Wöhlerstraße 11, 79108 Freiburg, Germany — 2TotalEnergies OneTech, 2 place Jean Millier, 92400 Courbevoie, France
Li containing transition metal oxides are known as good ionic conductors. Performing classical molecular dynamics simulations with a Morse potential model based on the Bond Valence method, the diffusion behavior of Li ions is investigated in crystalline and amorphous phases with the stoichiometries Li2ZrO3 and LiNbO3. The diffusivities are obtained from a statistical Arrhenius analysis of mean square displacement curves at different temperatures. The crystalline phase of Li2ZrO3 exhibits two well-defined migration mechanisms: vacancy-mediated migration is dominant below and a collective site exchange of Li ions above a crossover region between about 1700 and 1800 K. The latter mechanism, which is related to the formation of Frenkel pair defects and subsequent rotation of Li-Li pairs, also prevails in the amorphous phases with a strongly reduced activation energy. This is explained by a smaller equilibrium separation of Li ions in the amorphous phase than in the crystal structure. The demonstrated methodology and the discussed results shed light on a hitherto rarely described diffusion mechanism in ionic metal-oxide materials relevant for ion-battery applications.
Keywords: amorphous phase; molecular dynamics; ionic migration