Nanometer sized grains contain only about 900 atoms each. As the grain size decreases, there is a significant increase in the volume fraction of grain boundaries or interfaces. This characteristic strongly influences the chemical and physical properties of the material. For example, nanostructured ceramics are tougher and stronger than the coarser grained ceramics.
Nanophase metals exhibit significant increases in yield strength and elastic modulus.
There is also considerable interest in the generation of carbon nanostructures , which are related to the famous Buckyball . In addition, the use of nano-sized materials as fillers for composite materials is generating interest. These range from zero dimensional atom clusters to three dimensional equiaxed grain structure. Each class has at least one dimension in the nanometer range, as shown in Figure 1. Any multilayered material with layer thickness in the nanometer range is classified as one-dimensionally modulated .