Molecular Dynamics Simulations of the Oxidation of Aluminum Nanoparticles using the ReaxFF Reactive Force Field

S Hong and ACT van Duin, JOURNAL OF PHYSICAL CHEMISTRY C, 119, 17876-17886 (2015).

DOI: 10.1021/acs.jpcc.5b04650

We performed ReaxFF-molecular dynathics (MD) sin-nilations of the,oxidation of alnininum-, nanopartides (ANPs) at three different temperatures (300,- SOO, and 900 K) and two 'different iifial oXygen denSitids (0.13 and 0.26 g/cm(3)) to elucidate the mechanism of oxidation-kinetics of the ANPs and to study the oxidation states- in the -Oxide layer. Our result shows- that the' mechanism of the oxidation, of the- ANPs is as follows; hot-spots and highAemperature areas are -Created by adsorption and dissociation of oxygen molecules on the surface of the ANPs; void spates ate generated because of hot-,spots and high-temperature areas; the void spaces significantly IoWer a -reaction barrier 'for okygen difftiSion (by lip to '92%) and make this process exothermic. Subsequently; an oxide layer is developed by this accelerated oxygen diffusion. Our results also indicate that the oxidation of the ANPs depends on cOmbined effects Of the temperature and the oxygen gas pressure because such conditions have effects on not only the oxide layer thickness but- also the density of the oxide layer. These ReaxFF results are in good agreeinent with available experimental literature on aluminum oxidation kinetics.

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