Berlin 2008 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 60: Symposium: Bimetallic Nanosystems: Tuning Physical and Chemical Properties I (Invited Speakers: Harald Brune, Michael Hilgendorff, Konstantin Neyman)

O 60.5: Vortrag

Donnerstag, 28. Februar 2008, 11:15–11:30, MA 005

Non-Intensive Phase Diagrams of Pt-Rd Nanoalloys — Johann Pohl, •Karsten Albe, and Mathias Nalepa — Institut f. Materialwissenschaft, TU Darmstadt, Petersenstr. 23, D-64287 Darmstadt

We present computer simulation studies on size dependent phase diagrams of Pt-Rh nanoparticles, which exhibit ordered low temperature phases. We will first give a short review of a refined BOS mixing model, which is used in lattice Monte-Carlo simulations. These simulations serve as input for the thermodynamic integration of free energies as function of size and composition. The resulting phase diagrams will be discussed for different particle sizes. We specifically address the question of how to interpet a two-phase regions in the phase diagram and explore the role of surface segregation. Finally, the kinetics of alloying processes is studied for free and supported particles by dynamic Monte-Carlo simulations.