Classifications and Structures of Nanomaterials

Nanomaterials are characterized by free nanoparticles of various nanodimensions: 1D, 2D, or 3D in classifying nanosheets such as graphene, 2D needles or filaments, and 3D particles, including aggregates. These geometries can be included in a contiguous solid as dispersed or precipitated phases or contiguous nanocrystals forming nanograin solids. These nanomaterials structures are generally observed directly using imaging techniques such as SEM, TEM, FIM, STM, or AFM, which are principal characterization tools. The distinctive features of nanomaterials especially nanocrystalline forms are the high surface-to-volume ratio and the dominant role of interfacial (and surface) energy. Nanostructured materials might be thought of as the interfacial state. These issues of characterization and classification of nanomaterials and nanostructures as well as interfacial phenomena in nanomaterials are treated in this chapter.