In this introductory paper an attempt is made to give an overview of the area of nanostructured "materials irrespective of the synthesis process. The various microstructural features such as clusters or isolated nanoparticles, agglomerated nanopowders, consolidated nanomaterials and nanocomposite materials as well as all materials classes are considered. As an important component of modern research on nanomaterials a section describes the various characterization tools available. Based on these remarks some properties of nanostructured materials will be summarized emphasizing the property-microstructure relationships. Finally, a brief outlook on applications and initial industrial use of nanomaterials is presented.
IntroductionNanostructures are plentiful in nature. In the universe nanoparticles are distributed widely and are considered to be the building blocks in planet formation processes. Biological systems have built up inorganic-organic nanocomposite structures to improve the mechanical properties or to improve the optical, magnetic and chemical sensing in living species. As an example, nacre (mother-of-pearl) from the mollusc shell is a biologically formed lamellar ceramic, which "exhibits structural robustness despite the brittle nature of its constituents.[1] Figure 1 shows an SEM imge of a fracture surface of an abalone shell exhibiting the CaCO 3 -platelets which are se-