Nanotechnology, (nanotechnology) is a technology industry involved in the design, analysis, fabrication and application of structures, devices and systems by controlling shape, size on scale. nanometer (nm, 1 nm = 10−9 m). The boundary between nanotechnology and nano science is sometimes unclear, but they all have the same object as nanomaterials. [1]
Nanotechnology includes the following key issues:
Nano science basis
- Methods of observation and intervention on nanometer scale
- Fabrication of nanomaterials
- Application of nanomaterials
Critical size
The physical and chemical properties of materials all have a size limit. If the material is smaller than this size, its properties are completely changed. It is called critical size. Nanomaterials have special properties because their size is comparable to the critical dimensions of the properties of materials. For example, the resistance of a metal follows Ohm’s law at the macro size that we see every day. If we reduce the size of the material to less than the average free distance of the electron in the metal, which is usually worth several to several hundred nm, then Ohm’s law is no longer true. At that time the resistance of nanoscale objects would follow quantum rules. Not any nanoscale material has a different nature, it depends on the nature it is studied. Other properties such as electrical properties, magnetic properties, optical properties and other chemical properties are critical lengths in nm. That’s why science and technology are related to nanoscience and nanotechnology.
Classification of nanomaterials
Nanomaterials are materials in which at least one dimension is nanometer in size. Regarding the state of the material, people are divided into three states, solid, liquid and gas. Nanomaterials are currently focused on research, mainly solid materials, then liquids and gases.
Regarding the shape of materials, people are divided into the following categories:
- Non-dimensional nanomaterials (all three dimensions are nanoscale, no longer free for electronics), for example: nano-particles, nanoparticles.
- One-dimensional nanomaterials are materials in which two-dimensional nanoscale, electrons are free on one dimension (two-dimensional imprisonment), for example: nanowires, nanotubes.
- Two-dimensional nanomaterials are materials in which one-dimensional nano-sized, two-dimensional freedom, for example, thin films.
There are also nanostructured materials or nanocomposite in which only a part of the material has a nanometer size, or its structure has a non-dimensional, one-dimensional, two-dimensional nano interwoven.
Scientific basis of nanotechnology: There are three scientific bases for nanotechnology research.
Forward from classical to quantum properties For macroscopic materials consisting of many atoms, quantum effects are averaged with a lot of atoms (1 µm3 has about 1012 atoms) and can be removed through random fluctuations. But the nanostructures have fewer atoms, the quantum properties are more obvious. For example, a quantum dot can be thought of as an atom, it has energy levels like an atom.
Surface effect
When the material is nm in size, the atomic numbers on the surface will account for a significant proportion of the total number of atoms. Therefore surface-related effects, referred to as surface effects, will become important to make the properties of nanometer-sized materials different from that of bulk materials.
