Define nano-material and classify the nano-materials based on the dimensional constraints.

9. a) Define nano-material and classify the nano-materials based on the dimensional constraints.

Answer:

Nano-materials: Nano-materials can be defined as materials possessing, at minimum, one external dimension measuring 1-100nm.

Classification of nano-materials based on the dimensional constraints:

Based on the number of nano dimensions nano materials are classified in to the following types.

Zero-dimensional(0D) nano-materials: In case of OD nano-materials all three dimensions (x, y, z) are at nano-scale, i.e., no dimensions are greater than 100nm. It includes nanospheres and nanoclusters.

One-dimensional (1D) nano-materials: Here, two dimensions (x, y) are at nanoscale and the other is outside the nanoscale. This leads to needle shaped nano-materials. It includes nanofibres, nanotubes,
nanorods, and nanowires.

Two-dimensional (2D) nanomaterials: Here, one dimension (x) is at nanoscale and the other two are outside the nanoscale. The 2D nanomaterials exhibit platelike shapes. It includes nanofilms, nanolayers and nanocoatings with nanometre thickness.

Three-dimensional(3D) nanomaterials: These are the nanomaterials that are not confined to the nanoscale in any dimension. These materials have three arbitrary dimensions above 100 nm. The bulk (3D) nanomaterials are composed of a multiple arrangement of nanosize crystals in different orientations. It includes dispersions of nanoparticles, bundles of nanowires and nanotubes as well as multi nanolayers (polycrystals) in which the 0D, 1D and 2D structural elements are in close contact with each other and form interfaces.