Effect of the interface structure on the high-temperature morphology of supported metal clusters

The morphology of Pd clusters prepared by ultrahigh-vacuum condensation or wet impregnation on MgO and the structure of the interfaces are studied by weak-beam dark-field and high-resolution electron microscopy, according to the particle sizes. The shapes are stable when the particles are annealed at increasing temperature, they are close to the equilibrium forms. Their adhesion energy beta with the substrate is experimentally deduced from the Wulff-Kaishew construction. It decreases when the particle size increases, and with the formation of defects at the interface.