Mechanochemical approach for preparing nanostructural materials

Several mechanochemical methods for synthesizing nanostructural materials have been introduced in this paper. The methods are three different routes; one is a direct synthesis method, the second is a combination method, which composes of grinding, heating and washing, and the third is a doping one. Dry grinding a mixture facilitates the solid-state reaction (MC reaction), to form a product of fine particles with nanostructure of grains and their boundaries in lattice configuration. The micro-structure of material depends mainly on grinding energy and the composition of starting mixture. Under the grinding energy enough for mechanochemical synthesis, the synthesized material tends to be aggregated, so that the specific surface area (SSA) is not large. In order to increase the SSA, the combination method is recommended. The doping method is another concept, enabling us to cause a partial MC reaction in the fine particles. The chemical form and structure of the material depend mainly on a mixing ratio of the starting samples. The authors have attempted to form different functional materials such as catalysts from various starting samples by using a planetary mill, and introduced some of them in the present paper.