Nanotechnology is currently the fastest growing field of knowledge. It is a field operating at the level of atoms and molecules with materials whose structures and elements show peculiar and perfectly developed chemical, physical and biological properties caused by their nano-size.
The nanoscale refers to the order of atomic quantities. One nanometre corresponds to six carbon atoms arranged in series or to the size of 10 Angstromes, units often used in chemistry and physics to describe objects and phenomena on the atomic scale.
The beginning of nanotechnology is considered to be the 1950s when Richard P. Feynman, Nobel Laureate, gave his famous paper, “The Nanotechnology of the 1950s”. “There is Plenty of Room at the Bottom. The scientist presented his visions with the factories where nanomanufacturing machines producing diverse and complex products worked.
As early as 1960, 35-year-old engineer William H. McLellan was awarded the Nobel Prize for building a cube engine with a side of no more than 1/62 inch, weighing 250 micrograms and power of 1mW.
The next step in the use of electron beams was to recreate on a scale from Feyman’s 1985 Charles Dickens Two Cities Story by Thomas Newman at Standford University.
The 80s and 90s of the 20th century were a period of dynamic development of lithographic techniques and production of ultra-thin layers of crystals.
Already in 2007, Tehnion scientists placed the Old Testament text in Hebrew on a 0.5 square millimetre plate covered with gold silicone, carved with a concentrated stream of gallium ions.
This history is constantly evolving, giving newer and newer materials with unique properties, which are used in almost every area of human life.
Review of Nanotechnology issues
Coal was known for a long time as a fuel, an ingredient in shooting fuel, raw jewellery material, lubricant, dye and adsorbent. Two crystalline forms were known as diamond, a very hard semiconductor with a wide energy band, and a second graphite, a layered structure with metallic properties along the layers.
After the discovery of fullerene in 1985, a new allotropic carbon was suggested. Fulleren C60 is a practically spherical molecule composed of sixty carbon atoms arranged in pentagonal and hexagonal shapes, similar to football. Shortly after this event, derivatives were discovered: fullerene C60, fullerene C70 similar to American football, higher fullerenes, multi-walled fullerenes, grown fullerenes, and in 1991 carbon nanotubes.
Coal has four valence electrons, three of which are connected to neighbouring coals, and one remaining one is relocated throughout the structure, as are electrons in metals.
For this reason, graphite materials are sometimes considered to be metallic substances because they are electrically conductive. In fullerenes and nanotubes conductivity depends on spherical structure or nanotubes structure, which translates into interesting quantum phenomena.
The ideal structure of a diamond or graphite is a single crystal of unlimited size. From practical experience, thousands or hundreds of thousands of distances in one direction is already considered an unlimited size.
Distances between atomic distances are in the order of nanometre decimals (0.155 nm in a diamond), the physical properties inside the crystal at distances of a few micrometers from the surface are identical to those inside a large crystal, only on external surfaces there are differences. Fullerenes are particles of strictly defined dimensions
Nanotubes are molecules in their cross-section, and along their axis they are an unlimited solid. Often nanotubes are several hundred nanometers or even micrometers long, so, from the point of view of solid physics, their lengths are unlimited.
The physical properties of nanotubes are very interesting from the point of view of molecular physics in the cross-section of the tube and from the point of solids physics along the axis of the tube.
Such crystals have two types of pores: space between spheres and closed pores within spheres. The pores between spheres can be filled by different atoms, especially alkaline atoms. Under certain conditions, as doped fullerene crystals can become superconductors, and exhibit high superconductivity under temperature conditions even above 33K.
Additionally, closed pores inside the sphere may be filled with different atoms, which may affect different physicochemical properties. These are called endofullerenes.
Like fullerenes, nanotubes can form into nanotubes or ropes. Inside these bands, nanotubes are regularly packed, and pores are also found both between tubes and inside tubes. The word “tube” means that it is an empty tube as well as a long pore with a diameter of about 0.7nm.
Both fullerenes and endofullerenes, which have closed metal atoms in their structures, can be closed in other nanomaterial structures. The name peapod was invented especially for carbon nanotubes filled with fullerenes.
Nanotube ropes can form tangled nets resembling cotton wool or bunches of tangled threads, which are often called “backy papers”, referring to the American architect Buckminster Fuller, known for his multi-walled dome structure. Such material has three types of pores: large pores between nanotube ropes (the only visible pores with SEM), pores between tubes and pores inside tubes.