Nanostructured materials: basic concepts and microstructure

TLDR

Nanostructured materials are defined by a characteristic length scale of a few nanometers, and their properties differ from bulk counterparts due to size effects and numerous interfaces, with equilibrium examples produced by supramolecular chemistry and non‑equilibrium examples comprising nanocrystallites of varying orientations or compositions. This work aims to summarize the fundamental physical concepts and microstructural features of both equilibrium and non‑equilibrium nanostructured materials.

Abstract

Nanostructured Materials (NsM) are materials with a microstructure the characteristic length scale of which is on the order of a few (typically 1–10) nanometers. NsM may be in or far away from thermodynamic equilibrium. NsM synthesized by supramolecular chemistry are examples of NsM in thermodynamic equilibrium. NsM consisting of nanometer-sized crystallites (e.g. of Au or NaCl) with different crystallographic orientations and/or chemical compositions are far away from thermodynamic equilibrium. The properties of NsM deviate from those of single crystals (or coarse-grained polycrystals) and/or glasses with the same average chemical composition. This deviation results from the reduced size and/or dimensionality of the nanometer-sized crystallites as well as from the numerous interfaces between adjacent crystallites. An attempt is made to summarize the basic physical concepts and the microstructural features of equilibrium and non-equilibrium NsM.