As an emerging science and technology with the most market application potential, the potential importance of nanotechnology is beyond doubt. Some developed countries have invested a lot of money in research. For example, the United States was the first to set up a nanotechnology research center, and the Japanese Ministry of Culture, Education and Science listed nanotechnology as one of the four key research and development projects in materials science. In Germany, the University of Hamburg and the University of Mainz are the research centers of nanotechnology, and the government invests 65 million dollars every year to support the research of microsystems. In China, many scientific research institutions and colleges and universities also organize scientific research forces to carry out research on nanotechnology, and have made certain research achievements, mainly as follows:
The synthesis of aligned carbon nanotube arrays was completed by Xie Sishen, a researcher at the Institute of Physics, Chinese Academy of Sciences. They used chemical vapor phase method to efficiently prepare carbon nanotubes with a diameter of about 20 nanometers and a length of about 100 microns. The nanotube array with an area of 3 mm is prepared × 3mm, and the spacing between carbon nanotubes is 100 microns.
The preparation of gallium nitride nanorods was completed by Professor Fan Shoushan of Tsinghua University. They first used carbon nanotubes to prepare semiconductor GaN one-dimensional nanorods with a diameter of 3~40 nanometers and a length of up to micrometers, and proposed the concept of carbon nanotube confined reaction. In cooperation with Professor Dai Hongjie of Stanford University in the United States, we realized the self-organized growth of carbon nanotube arrays on silicon substrates for the first time in the world.
Quasi one-dimensional nanowires and nanocables were completed by Zhang Lide, a researcher at the Institute of Solid State Physics, Chinese Academy of Sciences. They used carbothermal reduction, sol gel soft chemical method and nano droplet epitaxy and other new technologies to synthesize tantalum carbide nanowire wrapped insulator SiO2 nanocable for the first time.
Qian Yitai of Shandong University and others completed the preparation of nano diamond by catalytic pyrolysis. They used catalytic pyrolysis to make carbon tetrachloride react with sodium to prepare diamond nano powder.
However, compared with the advanced technology of foreign developed countries, we still have a big gap. The German Ministry of Science and Technology once predicted the future market potential of nanotechnology: they believed that by 2000, the market capacity of nanostructure devices would reach 637.5 billion dollars, the market capacity of nano powders, nano composite ceramics and other nano composite materials would reach 545.7 billion dollars, the market capacity of nano processing technology would reach 44.2 billion dollars, and the market capacity of evaluation technology of nano materials would reach 2.72 billion dollars. It is predicted that the breakthrough of the market may be in the fields of information, communication, environment and medicine.
In a word, nanotechnology is becoming the focus of attention of the scientific and technological circles of all countries. As Academician Qian Xuesen predicted, "the structures around and below the nanometer will be the characteristics of the next stage of scientific and technological development, which will be a technological revolution, and thus another industrial revolution in the 21st century."
On October 19, 2011, the European Commission adopted the definition of nanomaterials, which was then interpreted. According to the definition of the European Commission, nanomaterial is a kind of powdery or agglomerated natural or artificial material composed of basic particles. One or more three-dimensional dimensions of this basic particle are between 1 nm and 100 nm, and the total number of this basic particle accounts for more than 50% of the total number of all particles in the whole material.
One nanometer is one billionth of a meter. On the nanometer scale, some materials have many special functions. Nanomaterials have been widely used in people's work and life.
In the definition of nanomaterials adopted by the European Commission, why is the basic particle size limited between 1 nm and 100 nm? The European Commission believes that the basic constituent particles of most known nanomaterials fall within this range, and of course, materials beyond this range may also have the characteristics of nanomaterials. This provision is to make the standard clear.
Why is it required that the total number of basic particles of nanomaterials account for more than 50% of the total number of all particles of the whole material? The European Commission believes that if the proportion of nano particles is too low, the nano characteristics of the whole material will be submerged, and 50% is a more appropriate proportion. In addition, using the quantity ratio of nano particles rather than the mass ratio as the measurement standard of nano materials can better reflect the characteristics of nano materials. Because the density of some nanomaterials is very low, they can already show obvious nanomaterial characteristics in the case of small mass ratio.
Why do nanomaterials include natural materials? The European Commission believes that nanomaterials should be defined according to the size of the basic constituent particles, whether they are natural or man-made. In fact, some natural materials also have the characteristics of artificial nanomaterials.
Why are materials with nanostructures excluded from nanomaterials? The European Commission believes that although this material also has the characteristics of nanomaterials, it is still unable to clearly define nanostructures, so it is not operable.
Why are products containing nanomaterials not nanomaterials? The European Commission believes that nanomaterials are raw materials or mixtures of raw materials. When they are made into products with other materials, they have formed new materials with other materials, so the products made are no longer nanomaterials.
However, the European Commission also recognized that this definition was imperfect, and therefore decided to revise it in 2014 according to the development of science and technology and the actual implementation of the definition. (Transferred from Xinhuanet)