GROWTH AND MORPHOLOGY OF PALLADIUM PARTICLES EPITAXIALLY DEPOSITED ON A MGO(100) SURFACE

Palladium particles (1.5-12 nm) have been epitaxially grown on UHV-cleaved MgO(100) surfaces. Their crystalline structure and their morphology have been studied by various TEM techniques. At high deposition temperatures, homogeneous distributions of particles, displaying the single shape of an half octahedron truncated on the top by a (100) plane, have been obtained. At low deposition temperature particles were flatter with mainly (100) facets. At high temperatures, on clean air-cleaved substrates, homogeneous distributions of very small particles (1.5-2 nm) with a high number density and sharp size distributions were obtained. These homogeneous distributions of well defined particles can be used in surface studies as model catalysts.