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MM: Fachverband Metall- und Materialphysik
MM 24: Nano structured materials II
MM 24.4: Talk
Wednesday, March 28, 2007, 17:30–17:45, H4
Molecular dynamics simulation of the formation of iron-platinum clusters — •Norbert Lümmen1 and Thomas Kraska2 — 1Institute for Physics and Technology, University in Bergen, Norway — 2Institute for Physical Chemistry, University Cologne, Germany
The formation of iron-platinum clusters from the vapour phase is investigated by molecular dynamics simulation. The metal interaction is modelled by an embedded atom potential method. Argon is added as carrier gas for removing the condensation heat from the system.
The first step of the particle formation is homogeneous nucleation. We found that in the iron-platinum system pure platinum nucleation takes place to a certain extent. We attribute this effect to the difference in cohesive energies of the two substances leading to heat transfer from platinum clusters to iron atoms which makes it less likely for them to condense at the same time due to their high temperature. This observation is in agreement with experimental results on the palladium-platinum system in the literature.
The proceeding growth process comprises surface growth, coalescence and agglomeration. The analysis of the atomic order shows that the disordered tetragonal face centred structure dominates. In order to obtain the ordered L10 structure we have run sinter simulations with different temperature programs applied to the carrier gas argon. Furthermore different cluster sizes ranging from 3 nm to 3.5 nm are analysed with respect to the structure formation. At the current state the onset of L10 formation can be observed.