SKM 2023 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 3: Development of Computational Methods: Evaporation, Growth and Oxidation – Density Functional, Tight Binding

MM 3.5: Vortrag

Montag, 27. März 2023, 11:15–11:30, SCH A 251

Dynamic restructuring of oxidation states in magnetite — •emre gürsoy¹, gregor b. vonbun-feldbauer², and robert h. meißner^1,3 — ¹Institute of Polymer and Composites, Hamburg University of Technology, Hamburg, Germany — ²Institute of Advanced Ceramics, Hamburg University of Technology, Hamburg, Germany — ³Institute of Surface Science, Helmholtz-Zentrum Hereon, Geesthacht, Germany

Magnetite is a mineral that undergoes a metal-insulator transition called the Verwey transition at 125 K (T_V). Its conducting behaviour above T_V is linked to electron hops between Fe²⁺ and Fe³⁺ on octahedral sites and complex oxidation state patterns emerge as a direct consequence. Oxidation states are frequently assessed using quantum mechanical methods, but these computationally expensive methods are not scalable to relevant systems with several thousand atoms. Therefore, a computationally inexpensive method that provides a detailed atomistic description of magnetite would be beneficial. We present a hybrid Monte Carlo/Molecular Dynamics (MC/MD) approach for atomistic modeling of magnetite, magnetite surfaces, and nanoparticles that can capture many aspects of this oxidation state patterning. It is based on swapping the oxidation states of Fe ions using MC either in simulated annealing, or in a hybrid combination with MD. We confirmed the accuracy of our model by comparison with oxidation states determined from density functional theory. This simple yet efficient approach paves the way to elucidate aspects of oxidation state ordering and electron hopping in inverse spinel structures in general.