Berlin 2008 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 23: Poster session

MM 23.35: Poster

Dienstag, 26. Februar 2008, 14:45–18:00, Poster B

Determination of lattice distortion in nanoparticles on strained substrates using molecular dynamics — Jian Zhou, •Srinivasa Saranu, and Ulrich Herr — Institut für Mikro- und Nanomaterialien, Universität Ulm, 89081 Ulm

Magnetoelastic anisotropies might provide a way to optimize the magnetic properties of nanoparticles. The experimental determination of strain in nanoparticles is often complicated by the low XRD intensities. We used the molecular dynamics simulation technique to determine the deformation of Co particles deposited on Ta or Cu substrates. Co particles of 4.5 nm diameter with fcc structure were built using a Wulff construction and subsequently deposited on the substrates with a kinetic energy of 0.1eV/atom. The structure and internal strain in the particles have been determined from simulated diffraction curves. In some cases we find a fcc-to-hcp phase transformation in the particles which turns out to be related to the impact energy and the interface structure between the particle and substrate. The analysis also shows that the landed particles are always tilted with respect to the substrate surface. The degree of tilt is associated with the shape of the Co Wulff polyhedron. We have also studied the deformation induced in the particles by a change of the lattice parameter of the substrate after the deposition. We find that only coherent or semicoherent interfaces can transfer strain from the substrate to the deposited Co particles effectively.