Numerical Studies of the Diffusion Processes and First Step Oxidation in Nickel-Oxygen Systems by Variable Charge Molecular Dynamics
Variable charge molecular dynamic simulations have been performed to study the diffusion mechanisms of oxygen atoms (O) in nickel (Ni) in the temperature range 950-1600 K and the very first steps of oxidation of monocrystalline nickel surfaces at 300 K and 950 K. The oxygen diffusivity can be well described by an Arrhenius law over the temperature range considered. The oxygen diffusion coefficient has been analysed and values of Ea = 1.99 eV for the activation energy and D0 = 39 cm2.s-1 for the pre-exponential factor were obtained. The first steps growth of the oxide layer show that after the dissociative chemisorption of the oxygen molecules on nickel surface, the oxidation leads to an island growth mode as observed experimentally.
Andreas Öchsner, Graeme E. Murch, Ali Shokuhfar and João M.P.Q. Delgado
S. Garruchet et al., "Numerical Studies of the Diffusion Processes and First Step Oxidation in Nickel-Oxygen Systems by Variable Charge Molecular Dynamics", Defect and Diffusion Forum, Vols. 297-301, pp. 513-518, 2010