STRUCTURAL CHARACTERISTICS OF FRACTAL CLUSTERS GROWN DURING VAPOR-SOLID TRANSFORMATION

Fractal growth of molybdena, iodine, and carbon during vapor-solid tra nsformation was studied experimentally. Three types of self-similar fr actal clusters were observed, respectively. These clusters included tw o different crystalline structures, that is, single crystal and amorph ous solid. The microstructure of single crystals included whiskers, ri bbonlike crystals, and dendrites. The whiskers or ribbonlike crystals stacked together easily, and formed a bifurcation aggregate such as a molybdena fractal cluster. Under certain conditions, some dendrites we re distorted and became branches of a network fluster. such as an iodi ne quasifractal cluster. The branching amorphous clusters of carbon ag gregated at the edge of a glass sample after being irradiated by an el ectron beam. It is revealed phenomenologically from the experimental r esults that microstructures of these fractal clusters depended strongl y on their growth conditions.