Dresden 2009 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 53: Nanostructures at surfaces: Dots, particles, clusters III

O 53.11: Vortrag

Donnerstag, 26. März 2009, 17:30–17:45, SCH A215

Thermodynamics and sintering kinetics of Pt-Rh nanoalloys from lattice Monte Carlo simulations — •Johan Pohl, Mathias Nalepa, and Karsten Albe — Institut f. Materialwissenschaft, TU Darmstadt, Petersenstr. 23, 64287 Darmstadt, Germany

Pt-Rh nanoparticles play an important role as catalytically active material in many devices, but an in depth understanding of the thermodynamics and kinetics of this nanoalloy is, however, still lacking.

We have therefore studied the thermodynamics and kinetics of Pt-Rh nanoparticles in the framework of a bond-order simulation mixing model. First, the bulk phase-diagram is calculated that includes ordered low-temperature phases as predicted from first-principles calculations. Next, the role of finite-size effects for the phase stability in nanoparticles is investigated by semi-grand canonical Monte-Carlo simulations and thermodynamic integration, while order parameters of the finite and bulk phases are discussed. Finally, the model is extended to account for the kinetics of vacancy and surface diffusion.

Simulations of the sintering process of free particles of different sizes as well as sintering on a substrate with varying metal-substrate interaction are presented and compared with results from sintering theory.