What are nanomaterials?
Nanomaterials are materials having at least one of their dimensions (length or width or height) in the range of 1-100 nm. This range is called the nanoscale or nanoscopic or nanometric range. The word nano is a unit prefix that originated from the Greek word that means dwarf or similar. In fact, one nanometer (nm) is a billionth of a meter i.e. 1 nm = 10-9m = 10Å.
Nanomaterials show unique properties like increased strength, toughness, hardness, ductility, melting point, efficient electrical properties, magnetic properties, catalytic properties, optical properties, and so on as compared to bulk materials.
Classification of Nanomaterials
Nanomaterials can be classified in various ways. On the basis of electrical properties, they can be classified as
- Conducting (metallic)
- Superconductivity (semiconductor)
- Non-conducting (insulators)
On the basis of magnetic properties, they can be classified as:
- Magnetic nanomaterials
- Non-magnetic nanomaterials
The most commonly adopted method of classification is based on their dimension. On the basis of dimensions, they are classified as:
- Zero-dimensional nanomaterials: Such materials have all three length scales Lx (length along X-axis), Ly (length along Y-axis, and Lz (length along Z-axis) in the nanoscopic range. Examples: Quantum dots, metallic nanoclusters, nanosphere, nanorods, nanocubes, etc.
- One-dimensional nanomaterials: In such materials, one of the dimensions is out of the nanoscopic range. Nanowires, nanotubes, etc. are some examples of one-dimensional nanomaterials.
- Two-dimensional nanomaterials: In these materials, any two dimensions are out of the nanoscopic range. Examples: Nanofilms, nanosheets, nano-coatings, and so on.
- Three-dimensional nanomaterials: In these materials, all three dimensions are out of the nanoscopic range.
Nanomaterials and Nanoparticles
In Nanoscience and Nanotechnology, both nanomaterials and nanoparticles terms are used vaguely. In fact, nanoparticles are nanomaterials having all three dimensions in the range of 1-100 nm i.e. they are zero-dimensional nanomaterials. In other words, all nanoparticles are nanomaterials but not all nanomaterials are nanoparticles. Moreover, nanoparticles can be metallic, semi-conducting, insulating, or hybrid type. It possesses unique properties as compared to bulk materials.
What are nanostructured materials?
Nanostructured materials are the materials that are formed by the assembly or repetition of nanometer-sized building blocks. The building blocks are called crystalline or grains. The building blocks may be zero-dimensional or one-dimensional or two-dimensional which are separated by different types of boundaries. On the basis of the shape of crystallites, these materials are classified as:
- Nanostructured materials having equiaxed crystallites
- Nanostructured materials having rod-shaped crystallites
- Nanostructured materials having layered-shaped crystallites
Nanostructured materials exhibit unique properties as compared to bulk structured materials.
Application of Nanomaterials
Nanomaterials are widely used in different sectors. Some of the major areas where nanomaterials seem highly applicable are listed below:
- Electronics and Nanoelectronics
- Nanosensors and nanoprobes
- Food and agriculture industry
- Personal care products and consumer goods
- Automobile industry
- Water treatment and the environment
- Medical diagnostics and related applications
- Energy sector applications
- Space applications
- Structural applications
- Nanotechnology in defense, and so on.