Classification of Nanostructures by Peeyush Mishra
- 1. P a g e | 1 Peeyush Mishra | NIT CALICUT CLASSIFICATION OF NANOSTRUCTURES Nanomaterials: ISO (International Organization for Standardization) defines nanomaterials as ‘material with any external dimension in the nanoscale (size range from approximately 1 – 100 nm) or having an internal structure or surface structure in the nanoscale’. Richard W. Seigel, the professor and director of Material Science and Engineering at Rensselaer Polytechnic Institute and fellow of the Material Science Society (MRS) classified nanostructured materials in the following way: 1. Zero dimensional: These are the materials having all the dimensions within the nanoscale (no dimensions are larger than 100 nm). Small clusters composed of a few to roughly a hundred metal atoms, and common spherical metal nanoparticles. Example: - Quantum dots, Nanodots, Nanoclusters and Fullerenes. 2. One dimensional: These are the materials having one dimension outside the nanoscale (one dimension is larger than 100 nm). Major growth occurs in one dimension, whereas it is limited in the other two dimensions Example: - Nanowires, Nanorods, Nanotubes, Nanowires, Nanobelts, Nanopillars, Carbon Nanotubes (CNT).
- 2. P a g e | 2 Peeyush Mishra | NIT CALICUT 3. Two dimensional: These are the materials having two dimensions outside the nanoscale. (Two dimensions are larger than 100nm). This class exhibits plate-like shapes. Example: - Graphene, nanofilms, nanoplates, nanonetwork, planar triangle, hexagons and discs. 4. Three dimensional: These are the materials that are not confined to the nanoscale in any dimensions. (All three dimensions are larger than 100nm). Major growth occurs in all three dimensions, more complicated structures like various polyhedral, as well as assemblies of 0D, 1D and 2D nanostructures Example: -Graphite, Diamond, Nanosponge, Nanocomposite, dispersion of nanoparticles, a bundle of nanowires. Nanomaterials Zero Dimensional One Dimensional Two Dimensional Three Dimensional
- 3. P a g e | 3 Peeyush Mishra | NIT CALICUT Identifying the nanostructures (a) 0D Spheres and clusters (b)1D Nanofibers, wires and rods (c)2D films, plates and networks (d)3D Nanomaterials TEM images of various dimensional ZnO nanostructures 1. 0D ZnO nanospheres
- 4. P a g e | 4 Peeyush Mishra | NIT CALICUT 2. 1D ZnO Nanowires 3. 2D ZnO Nanosheets 4. 3D ZnO nanostructure (It’s aggregates of 1D Zinc Nanotubes)
- 5. P a g e | 5 Peeyush Mishra | NIT CALICUT Basic Synthetic Approach Top-down Approach Bottom-up Approach Breaking of large objects Assembling atoms and molecules Structure sizes in the medium to lower nm range starting from large materials entity Designing Nanoparticles of any size and morphology by unit-by- unit deposition of the constituents.
- 6. P a g e | 6 Peeyush Mishra | NIT CALICUT Keywords: Quantum dots: 0D structures having all the dimensions less than 10nm Nanodots: 0D structures having all dimensions less than 100nm; perfectly spherical in shape. Nanoclusters:0D structures having all dimensions less than 100nm; they are asymmetrical in shape. Fullerenes: 0D carbon structure made up of single and double bonds forming a closed mesh shape; made from fused rings of 5- 7 atoms. Initial Stage Final Stage Initial Stage
- 7. P a g e | 7 Peeyush Mishra | NIT CALICUT Nanotube:1D structures which are hollow from inside Nanorod: 1D structures which are solids and are not hollow from within. Nanowires: 1D structures which are known for their electrical conducting property. Nanopillars and Nanobelts: 1D structures named on basis of their shape. (refer identification of nanostructures on page-3) Nanofilms, Nanoplates and Nanonetwork: 2D structures which have been named on basis of their shape (refer identification of nanostructures on page-3) Graphene: sp2 hybridised cyclic structures containing double bonds having strength higher than even diamond. Nanosponge: 3D structures which are porous in nature (having pores and cavities in nanometre range) Nanocomposites:3D structures which are formed by piling of nanoparticles in bulk Graphite: Aggregates of graphene arranged in layer fashion. Diamond: sp3 hybridised carbon molecules arranging themselves to form a crystal structure
- 8. P a g e | 8 Peeyush Mishra | NIT CALICUT TEM microscope (Transmission electron microscope relies on a beam of electrons for the formation of an image of the specimen; it can have measure objects less than 100 nm with precision) Summary: We can classify nanomaterials based on two different parameters: 1. We can classify them on basis of number of dimensions lying outside the nanoscale region- 0D,1D,2D and 3D. 2. We can classify them on basis of the way nanoparticles can be formed- top-down method and bottom-up method Acknowledgement: I would like to state that except pictures which have been taken from Google images, everything has been written and made by me. This assignment is plagiarism-free.