Coupling of structural and energetic fluctuations in Co nanometre-sized particles

摘要

Molecular dynamics simulations have been employed to investigate the dynamic behaviour of an unsupported Co particle of about 5 nm in size. Surface effects induce a martensitic hcp-to-fcc phase transition at temperatures significantly lower than the one observed in the case of bulk systems. The transformation nucleates at the surface and is mediated by atoms with defective coordination. Under proper conditions, the crystalline arrangement undergoes an oscillating behaviour governed by fluctuations in the potential energy of atoms in the interior of the particle.