Eur. Phys. J. D 52, 51-54 (2009)
https://doi.org/10.1140/epjd/e2008-00246-4

A multi-range order parameter for binary alloy bulk materials and nanoparticles

¹ Physique des Solides Irradiés et des Nanostructures CP234, Université Libre de Bruxelles, Bruxelles, Belgium
² Institute of Electronics, Bulgarian Academy of Sciences, 72 Tsarigradsko Chaussée, 1784 Sofia, Bulgaria

Corresponding author: ^a iatanaso@ulb.ac.be

Received: 19 September 2008
Published online: 24 January 2009

Abstract

A multi-range order parameter for binary alloys is considered, valid for bulk materials and nanoparticles. The difference between two common definitions is discussed, arising when applied to small systems. Its properties are illustrated on the example of the order/disorder transitions in Au–Pd fcc bulk materials and nanoparticles. The thermodynamic equilibrium states of these systems are predicted by Metropolis Monte Carlo sampling in the canonical (NPT) ensemble and an embedded-atom model potential. Short range order is found partially preserved by the transition while long range order vanishes. The order of intermediate ranges is found to be particularly sensitive to the presence of anti-phase boundaries (APBs) in both, bulk alloys and nanoparticles.