Structure and thermodynamics of CuNi nanoalloys by a new DFT-fitted atomistic potential

EMANUELE PANIZON; JIMENA A. OLMOS ASAR; MARIA PERESSI; RICCARDO FERRANDO

PHYSICAL CHEMISTRY CHEMICAL PHYSICS

ROYAL SOC CHEMISTRY

Lugar: CAMBRIDGE; Año: 2015 vol. 17 p. 28068 - 28075

1463-9076

Shape, stability and chemical ordering patterns of CuNi nanoalloys are studied as a function of size, composition and temperature. A new parametrization of an atomistic potential for CuNi is developed on the basis of ab-initio calculations. The potential is validated against experimental bulk properties, and ab-initio results for nanoalloys of sizes up to 147 atoms and for surface alloys. The potential is used to determine the chemical ordering patterns for nanoparticles of diameters up to 3 nm and different structural motifs (decahedra, truncated octahedra and icosahedra), both for the ground state and in a wide range of temperatures. The results show that the two elements do not intermix in the ground state, but there is a disordering towards solid-solution patterns in the core starting from room temperature. This order-disorder transition presents different characteristics in the icosahedral, decahedral and fcc nanoalloys.