Atomic force and scanning tunneling microscopy analysis of palladium and silver nanophase materials

Atomic force and scanning tunneling microscopy images of nanophase palladium and silver materials taken on various length scales are presented. The samples show a conformational packing of individual nanometer-sized clusters. In the case of silver, islands of clusters are observed on micrometer length scales. The islands are very tlat and separated by deep crevices. The grains (clusters) within the islands are closely packed with shapes adjusting to the neighboring grains. The islands are compact, either equiaxed or oblong in shape. Average island diameters of 200-300 nm. and average grain sizes of 20-50 nm were measured. The height variations on the islands are between 5 and 15 nm. The crevices are between 200 and 400 nm deep. In the case of palladium, the clusters are more uniformly packed and do not appear to be agglomerated in islands. Palladium grain sizes typically of 15 nm were measured along with corrugations of 10 nm in the closely packed areas.