Abstract

In the 21st century, the rapid development of new energy, information, biotechnology, environment, advanced manufacturing technology, and national defenses will inevitably put new demands on materials and materials properties, such as high energy density, ultrafast transmission of components, miniaturization, intelligence, and high integration. Recent years, nanotechnologies have made great progress, and nanomaterials have been found to have many important uses in research and application. Owing to the surface effect, quantum size effect, small size effect, and macroscopic quantum tunneling effect, nanomaterials exhibit remarkable specific properties different from that of the bulk, which show excellent prospects in every field as next-generation materials. There are a large number of approaches to fabricate nanomaterials. However, there is no specific standard of classification. According to original state of the material, the preparation method can be divided into solid-phase method, liquid-phase method, and gas-phase method. A more simple classification, which involves physical and chemical methods according to the main aspect of matter change of the preparation roads, is introduced in this chapter.