Accession Number:

ADA285370

Title:

Molecularly Designed Ultrafine/Nanostructured Materials

Descriptive Note:

Symposium proceedings, no. 351, 4-8 Apr 1994

Corporate Author:

MATERIALS RESEARCH SOCIETY PITTSBURGH PA

Report Date:

1994-04-08

Pagination or Media Count:

465.0

Abstract:

Nanostructured materials are usually defined as having some length scale smaller than 100 nm in at least one dimension. An important subset of this group of materials is powders with particle size less than 100 nm, and polycrystalline materials, made by consolidating these powders in such a way as to retain a grain size below this limit. The choice of 100 nm stems from the fact that many physical, optical, and magnetic properties have characteristic lengths in this range. As grain or particle size is reduced below this characteristic length, the properties associated with these phenomena are radically altered. A frequently cited example is the freezing out of mechanisms for generating glissile dislocations. Another reason for expecting remarkable properties in nanostructured polycrystalline materials is the very high proportion of atoms at, or near, grain boundaries as high as fifty percent or greater for grain sizes below five or ten nanometers. This leads, for example, to very rapid diffusion coupled with very short diffusion distances.

Subject Categories:

  • Inorganic Chemistry
  • Laminates and Composite Materials
  • Crystallography
  • Atomic and Molecular Physics and Spectroscopy

Distribution Statement:

APPROVED FOR PUBLIC RELEASE