MECHANICAL INSTABILITY OF OXIDIZED METAL-CLUSTERS

A mechanism to explain the complete oxidation of small metal clusters is proposed, based on the occurrence of a mechanical instability drive n by the expansion of the progressively oxidized cluster surface and t he subsequent stress relaxation. Molecular dynamics simulations of sph erical Pd clusters show that an expanded surface layer is capable of s training the inner core of the cluster up to the point of inducing cav itation. These findings allow the interpretation of recent experimenta l results in which oxidized Pd clusters exhibit a hollow spherical sha pe.