Nanomaterials and Nanotechnology
No TL;DR found
Abstract
Nanomaterials: heterogeneous materials with a grain size (crystallite size) below 100 nm, at least in one direction (colloidal size range), usually measured by X-ray diffraction (Scherrer line broadening). The width of the interfacial region (phase boundary) between two nanosized (nanocrystalline) grains is usually estimated to be approx. 1 nm. Many of the exceptional properties of nanomaterials are due to the fact that with decreasing grain size the interfaces become an increasingly important (and below a grain size of approx. 10 nm the decisive) factor of the microstructure. In terms of volume fraction all grain boundary phases together make up approx. 50 % when the grain size is approx. 5 nm. A recent point of concern are the uninvestigated health hazards of nanopowders. Of course, these health hazards are especially relevant when nanopowders are to be used in upcoming commerical technologies.