Thermodynamics of surface compositional segregation in Ni-Co nanoparticles

Abstract

Thermodynamic analysis of a Ni-Co alloy nanoparticle (atomic ratio 1:1) is carried out to study the influence of size effect on surface compositional segregation. The surface compositions of Ni-Co nanoparticles are calculated based on the regular solution model, which takes into account of the size effect, and compared with that of bulk alloy particles with a larger size. It is observed that the segregated surface compositions in the Ni-Co binary alloy single-crystal nanoparticles (with particle diameter of 10-100 nm) are few times larger than that of the corresponding bulk single crystal (with the particle diameter > 100 nm). The details of the thermodynamic modeling and the calculated surface compositions due to segregation are discussed. © 2002 Elsevier Science B.V. All rights reserved.