INFIQC   05475
INSTITUTO DE INVESTIGACIONES EN FISICO- QUIMICA DE CORDOBA
Unidad Ejecutora - UE
artículos
Título:
On the Occurrence of Stable and Metastable States in Metallic Core-shell Nanoparticles
Autor/es:
O. A. OVIEDO, M. M. MARISCAL AND E. P. M. LEIVA
Revista:
Physical Chemistry Chemical Physics
Referencias:
Año: 2009
Resumen:
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Following the
framework established by Hill and Chamberlin [PNAS 95 (1998) 12779] to analyze
the extension of thermodynamics of small systems to metastable states, we have adopted
the same basic ideas to study the thermodynamic stability of core-shell
nanoparticles. For the first time we are able to address the question of
whether or not core-shell nanoparticles have a limit of stability when they are
under oversaturation conditions. In this situation the probablity density exhibit
multiple local maxima associated with different core-shell metastable states.
The decrease of the free energy barriers for the growth of the bulk phase is
analyzed for increasing oversaturation. At large positive oversaturations, the
barrier disappears and the core-shell NP become unstable with respect to the
bulk deposit. A brief discussion on the model is made illustrating its
application to a specific system by means of computer simulations using
realistic interatomic potentials. One of the most striking results of these
specific studies is the occurrence or not of a core-shell under undersaturation
conditions depending on nanoparticle size.