Migration brownienne de cristallites sur une surface et relation avec l'épitaxie: I. Partie expérimentale

Abstract

During the condensation of crystalline substance A on a crystalline surface (B), the crystallites (A) which appear, are usually supposed to be immobile. Experiments with gold (A), diameters between 10–30Å, adhering on the (100) surface of KCl (B), show that crystallites (A) have a measurable brownian translation motion even at 70°C. The diffusion coefficient of the crystallites is strongly temperature dependent, so that an activation enthalpy of migration can be defined, which is a function of the crystallite size. The crystallites A are in motion only if A and B are not in epitaxial relation. During the translation motion, the crystallites rotate and obtain their epitaxial order.