Nanomaterials

nanomaterials
Nanomaterials refer to materials that are at least one dimension in a three-dimensional space at
a nanometer size (0.1-100 nm) or composed of them as basic units, which is roughly equivalent
to a scale in which 10 to 100 atoms are closely arrangedtogether.
Range: 1-100nm
Category: Materialcomposed of basic units
. Table of Contents
. .1 Development
. .2 Nanostructure
. .3 Technical Specifications
. .4 Application
. .5 New materials
. .6 Material Classification
. .▪Nanoceramic
. . Feel nano powder
. . Nanofiber
. .▪Nanofilm
. . Feel nano block
. .7 Preparation method
. .8 Research results
. .9 Five major effects
. . Feel volume effect
. .. Surface effect
. .. Quantum size
. .. Quantum tunnel
. .▪ Dielectric limit
. .10 Status
. 11 Two-dimensional nano

Development
The two functional projects of "functionalization of nanocomposite polyurethane
synthetic leather materials" and "application of nanomaterials in vacuum insulation
panels" have made great progress. Polyurethane synthetic leather with negative ion
release function and release amount up to 2000 is in line with the strategic upgrading
direction of eco-friendly synthetic leather, and is undergoing pilot scale-up research.
The successful development and further industrialization of this product will be able to
upgrade the products of more than 300 peer companies. The thermal conductivity of the
nanocomposite core material prepared by the alliance can be controlled to as low as
4.4mW/mK. The product has already achieved pilot production in the enterprise and is
building a large-scale production line.
The alliance will focus on the development of flame-retardant high-efficiency vacuum
insulation panels and their application research and development and industrialization in
the field of building exterior wall insulation. The development of this technology will further
promote the improvement of China's building energy-saving and environmental protection
technology, and drive the Anhui nano-materials industry into high-speed. Development
period. Composite oxide one-dimensional and
zero-dimensional single crystal nanomaterials
In terms of size, the size of fine particles which usually produce a significant change
in physicochemical properties is below 0.1 μm (Note: 1 m = 1000 mm, 1 mm = 1000 μm, 1
μm = 1000 nm, 1 nm = 10 Å), ie Below 100 nm. Therefore, particles with a particle size of
1 to 100 nm are called ultrafine particles and are also a nanomaterial.
Nano-metal materials were successfully developed in the mid-1980s. Later,
nano-semiconductor films, nano-ceramics, nano-ceramic materials and nano-biomedical
materials were introduced.
The nano-scale structural material is simply referred to as a nanometer material, and
the size of the structural unit is between 1 nm and 100 nm. Since its size is close to the
coherence length of electrons, its properties change greatly due to the self-organization
caused by strong coherence. Moreover, its size is close to the wavelength of light, and its

special effect with large surface, so its characteristics, such as melting point, magnetic
properties, optical, thermal conductivity, conductive properties, etc., are often different
from the overall state of the material. The nature of the performance.Nanoparticle
materials, also known as ultrafine particulate materials, consist of nanoparticles.
Nanoparticles, also called ultrafine particles, generally refer to particles between 1 and
100 nm in size, which are transitional regions at the junction of clusters and macroscopic
objects. Such systems are not typical from the microscopic and macroscopic perspectives.
The microscopic system is also an atypical macroscopic system. It is a typical mesoscopic
system with surface effects, small size effects and macroscopic quantum tunneling effects.
When people subdivide macroscopic objects into ultrafine particles (nanoscale), it will
show many singular characteristics, namely its
Rare earth nanomaterial
The optical, thermal, electrical, magnetic, mechanical, and chemical properties will be
significantly different from those of bulk solids.
The broad scope of nanotechnology can include nanomaterial technology and
nanofabrication technology, nanometer measurement technology, and nanometer
application technology. Among them, nanomaterial technology focuses on the production
of nano-functional materials (ultrafine powder, coating, nano-modified materials, etc.),
performance testing techniques (chemical composition, microstructure, surface
morphology, materials, chemicals, electricity, magnetism, heat and optics, etc.)
performance). Nanofabrication technology includes precision machining technology
(energy beam processing, etc.) and scanning probe technology.
Nanomaterials have certain uniqueness. When the material scale is small to a certain
extent, it must be replaced by quantum mechanics instead of traditional mechanics to
describe its behavior. When the particle size is reduced from 10 micrometers to 10
nanometers, the particle size Although it is changed to 1000 times, it will be 10 times as
large as 9 times in terms of volume, so there will be a significant difference in behavior
between the two.

The reason why nanoparticles are different from bulk materials is that their surface
area is relatively increased, that is, the surface of the ultrafine particles is covered with a
stepped structure, which represents unstable atoms with high surface energy. Such atoms
are highly susceptible to adsorption bonding with foreign atoms and provide a large
surface of active atoms due to particle size reduction.
As far as the melting point is concerned, in the nanopowder, since each particle has a
small number of atoms, the surface atoms are in an unstable state, and the amplitude of
the surface lattice vibration is large, so that the surface energy is high, resulting in the
unique thermal properties of the ultrafine particles. That is, the melting point is lowered,
and the nano powder is easily sintered at a lower temperature than the conventional
powder, and becomes a good sintering promoting material.Generally, the common
magnetic substances belong to a collection of multi-magnetic regions. When the particle
size is small enough to distinguish the magnetic regions, a magnetic substance of a single
magnetic region is formed. Therefore, when the magnetic material is formed into ultrafine
particles or a film, it becomes an excellent magnetic material.
The particle size of the nanoparticles (10 nm to 100 nm) is smaller than the length of
the light wave and therefore will have a complex interaction with the incident light. Under
appropriate conditions of evaporation and deposition of metals, ferrous black ultrafine
particles, called metal black, which are easily absorbed by light, are obtained, which is in
sharp contrast to the high-reflectivity gloss surface of the metal formed by vacuum coating.
Nanomaterials can be applied to infrared sensor materials due to their high light
absorption rate.
In 1861, with the establishment of colloidal chemistry, scientists began research work
on particle systems with diameters ranging from 1 to 100 nm.
The truly conscious study of nanoparticles can be traced back to Japan's "smoke
test" for military needs in the 1930s, but was limited by the test level and conditions at the
time, although the world's first ultra-micro was made by vacuum evaporation. Lead
powder, but the light absorption performance is very unstable.
In the 1960s, people began to study discrete nanoparticles. In 1963, Uyeda used
metal evaporation and condensation method to prepare metal nanoparticles, and
conducted electron microscopy and electron diffraction studies. In 1984, Gleiter of
Saarland University in Germany and Siegal of the Argonne Laboratory in the United
States succeeded in producing nano-powder of pure substance. Gleiter in-situ
pressure-molded iron particles with a particle diameter of 6 nm under high vacuum

conditions, and sintered nano-crystal blocks, which made the research of nano-materials
enter a new stage.
The first International Conference on Nanoscience & Technology Conference was
held in the United States in July 1990, officially announcing that nanomaterial science is a
new branch of materials science.
Since the advent of nanoparticulate materials in the 1970s, the connotation and
characteristics of research can be roughly divided into three stages:
The first stage (before 1990): mainly in the laboratory to explore various methods to
prepare various materials of nanoparticle powder or synthetic bulk, research and
evaluation methods, explore the special properties of nanomaterials different from
ordinary materials; Research objects are generally limited to single materials and
single-phase materials, which are commonly referred to internationally as nanocrystalline
or nanophase materials.
The second stage (1990~1994): The hotspot of people's attention is how to use the
physical and chemical properties that nanomaterials have been explored to design
nanocomposites. The synthesis and physical properties of composite materials have once
become the leading direction of nanomaterials research.
The third stage (1994-present): Nano-assembly systems, artificially assembled and
synthesized nano-structured material systems are becoming a new hotspot in
nanomaterials research. Such materials are internationally referred to as nano-assembled
material systems or nano-scale patterned materials. Its basic connotation is that
nano-particles and their nano-filaments and tubes are assembled into a system with
nanostructures in one-dimensional, two-dimensional and three-dimensional space.
Nano-structure
Nanostructures are a new system constructed or built on a nanoscale scale based on
certain laws. It includes nano-array systems, mesoporous assembly systems, and film
inlay systems. Research on nanoarray systems has focused on two-dimensional systems
formed by neatly aligning metal nanoparticles or semiconductor nanoparticles on an
insulating substrate. The nanoparticle and mesoporous solid assembly system has
become a research hotspot due to the characteristics of the microparticle itself and the
coupling effect with the matrix of the interface. According to the kind of support, it can be
divided into inorganic media. There are two types of pore complexes and polymer

mesoporous composites, which can be divided into ordered mesoporous complexes and
disordered mesoporous complexes according to the state of the support. In the film
mosaic system, the main research on the nanoparticle film is based on the electrical and
magnetic properties of the system. American scientists use self-assembly technology to
form hundreds of single-walled carbon nanotubes into the crystal cord "Ropes", which has
metallic properties, resistivity less than 0.0001 Ω / m at room temperature; assembly of
nano-triiodide to nylon-11 Above, it has photoconductivity under X-ray irradiation, and the
use of this property lays the foundation for the development of digital radiography.
Technical indicators
Nano-alumina appearance White powder.
Nano-alumina crystal phase γ phase.
The average particle size of nano-alumina (nm) is 20±5.
The nano-alumina content is greater than 99.9%.
Melting point: 2010°C-2050 °C
Boiling point: 2980 °C
Relative density (water = 1): 3.97-4.0
Application range
1. Natural nanomaterials
Turtles lay their eggs on the beaches of Florida, USA, but the young turtles after birth
are able to survive and grow up in order to find food, but to swim to the waters near the UK.
Finally, the grown turtles will return to the beaches of Florida to lay their eggs. It takes
about 5 to 6 years to go back and forth. Why are sea turtles capable of tens of thousands

of kilometers of long-distance trek? They rely on nano-magnetic materials in the head to
navigate them accurately.
When biologists study why pigeons, dolphins, butterflies, bees and other creatures
never lose their way, they also find that there are also nanomaterials in these organisms
for navigation.
2, nano magnetic materials
Most of the nanomaterials used in practice are manufactured by hand. Nano
magnetic materials have very special magnetic properties, small size of nanoparticles,
single magnetic domain structure and high coercivity. Magnetic recording materials made
of it not only have good sound quality, image and signal-to-noise ratio, but also record.
The density is several times higher than γ-Fe2O3. Superparamagnetic ferromagnetic
nanoparticles can also be made into magnetic liquids for use in electroacoustic devices,
damping devices, rotary sealing and lubrication and beneficiation.
3, nano ceramic materials
In the traditional ceramic materials, the crystal grains are not easy to slide, the
material is brittle, and the sintering temperature is high. Nano-ceramics have small grain
size and crystal grains are easy to move on other crystal grains. Therefore, nano-ceramic
materials have extremely high strength and high toughness and good ductility. These
characteristics make nano-ceramic materials can be used at normal temperature or
sub-high temperature. Perform cold working. If the nano ceramic particles are processed
at a sub-high temperature and then surface annealed, the nano-material can be used as a
surface to maintain the hardness and chemical stability of the conventional ceramic
material, while the interior still has the high performance of the nano-material ductility.
ceramics.
4, nanosensor
Ceramics such as nano-zirconium dioxide, nickel oxide, and titanium dioxide are very
sensitive to temperature changes, infrared rays, and automobile exhaust. Therefore, they
can be used to make temperature sensors, infrared detectors and automobile exhaust gas
detectors, and the detection sensitivity is much higher than that of ordinary ceramic
sensors of the same type.
5, nano tilt function material
In aerospace oxyhydrogen engines, the inner surface of the combustion chamber
needs to be resistant to high temperatures, and its outer surface is in contact with the

coolant. Therefore, the inner surface should be made of ceramic, and the outer surface
should be made of metal with good thermal conductivity. But bulk ceramics and metals
are difficult to combine. If the composition is gradually changed continuously between
metal and ceramic during production, let the metal and ceramic "you have me, I have you",
and finally can be combined to form a tilting functional material, which means that The
composition changes like a sloping ladder. When the metal and ceramic nanoparticles are
mixed and sintered according to the requirements of gradually changing the content, the
requirements for high temperature resistance on the inner side of the combustion
chamber and good thermal conductivity on the outer side can be achieved.
6, nano semiconductor materials
Semiconductor materials such as silicon and gallium arsenide are made into nano
materials and have many excellent properties. For example, the quantum tunneling effect
in nano-semiconductors causes the electron transport of some semiconductor materials
to be abnormal, the electrical conductivity to decrease, and the electrical and thermal
conductivity to decrease with the decrease of the particle size, and even a negative value.
These characteristics play an important role in the fields of large-scale integrated circuit
devices and optoelectronic devices.
By using semiconductor nanoparticles, a novel solar cell with high photoelectric
conversion efficiency and working normally even in rainy days can be prepared. Since the
electrons and holes generated by the nano-semiconductor particles are highly reduced
and oxidized, they can oxidize toxic inorganic substances, degrade most organic
substances, and finally produce non-toxic and odorless carbon dioxide, water, etc., Solar
energy can be used to catalyze the decomposition of inorganic and organic materials by
means of semiconductor nanoparticles.
7, nano catalytic materials
Nanoparticles are an excellent catalyst because of the small size of the nanoparticles,
the large volume fraction of the surface, the chemical bond state and electronic state of
the surface are different from the interior of the particles, and the surface atoms are
incompletely coordinated, resulting in an increase in the active position of the surface. It
has the basic conditions as a catalyst.
Nanoparticles of nickel or copper-zinc compounds are excellent catalysts for the
hydrogenation of certain organics and can replace expensive platinum or palladium
catalysts. The nanoplatinum black catalyst can lower the temperature of the oxidation
reaction of ethylene from 600 ° C to room temperature.

8, medical applications
The size of red blood cells in the blood is 6,000 to 9 000 nm, and the nanoparticles
are only a few nanometers in size, and are actually much smaller than red blood cells, so
they can move freely in the blood. If various therapeutic nanoparticles are injected into
various parts of the human body, the lesions can be examined and treated, and the effect
is better than the traditional injection and medication.
Carbon materials have very good blood compatibility. The 21st century artificial heart
valves deposit a layer of pyrolytic carbon or diamond-like carbon on the material substrate.
However, this deposition process is complicated and generally only suitable for the
preparation of hard materials.
Interventional balloons and catheters are generally prepared from highly elastic
polyurethane materials. By introducing carbon nanotube materials with high aspect ratio
and pure carbon atoms into highly elastic polyurethanes, we can make this polymer
material Maintaining its excellent mechanical properties and easy processing and forming
properties, on the one hand, better blood compatibility.
The experimental results show that the nanocomposite causes a decrease in the
degree of blood hemolysis and a decrease in the degree of activation of platelets.
The use of nanotechnology enables the production process of pharmaceuticals to
become more and more sophisticated, and the use of atomic and molecular arrangements
directly on the scale of nanomaterials to produce drugs with specific functions.
Nanomaterial particles will make the drug transfer more convenient in the human body.
Smart drugs wrapped with several layers of nanoparticles can actively search for and
attack cancer cells or repair damaged tissues. New diagnostic instruments using
nanotechnology can detect a variety of diseases through the detection of small amounts
of blood and proteins and DNA. Through the special properties of nanoparticles, the
surface of the nanoparticles is modified to form some drug delivery vehicles with targeted,
controlled release and easy detection. It provides a new method for the treatment of local
lesions and opens up a new direction for drug development.
9, nano computer
The world's first electronic computer was born in 1945. It was jointly developed by the
American University and the Department of the Army. It has a total of 18 000 tubes and a
total weight of 30 tons. It covers an area of about 170 m2 and can be regarded as the last
one. It’s a big thing, but it can only do 5,000 operations in 1 s.After half a century, due to
the development of integrated circuit technology, microelectronics, information storage

technology, computer language and programming technology, computer technology has
developed rapidly. Today's computer is small and exquisite, can be placed on a computer
desk, it weighs only one ten thousandth of the ancestors, but the computing speed is far
more than the first generation of electronic computers.
If nanotechnology is used to construct electronic computer devices, then this future
computer will be a kind of "molecular computer", which is far less portable than today's
computers, and will also bring social benefits to materials and energy. Come to a very
substantial benefit.
It is possible to read from a hard disk reader and a nano-material memory chip with a
storage capacity of a thousand times that of a chip. Computers can be reduced to
"handheld computers" after the widespread use of nanomaterials.
10, carbon nanotubes
In 1991, Japanese experts prepared a material called "carbon nanotubes", which is a
combination of many hexagonal ring carbon atoms, or a coaxial one. The root tube is
assembled together. Both ends of such single and multi-layered tubes are often sealed as
shown.
The diameter of the tubular composed of carbon atoms and the size of the tube
length are both nanometer-scale and are therefore referred to as carbon nanotubes. Its
tensile strength is 100 times higher than that of steel, and its electrical conductivity is
higher than that of copper.
The carbon nanotubes are heated to about 700 °C in the air, so that the carbon atoms
at the top seal of the tube are destroyed by oxidation, and become an open carbon
nanotube. Then, the low melting point metal (such as lead) is evaporated by an electron
beam and condensed on the open carbon nanotubes. Due to the siphoning action, the
metal enters the hollow core of the carbon nanotube. Since the diameter of the carbon
nanotubes is extremely small, the wires formed in the tubes are also extremely fine, and
are called nanowires, and the size effect produced by them is superconducting. Therefore,
carbon nanotubes plus nanowires may become new superconductors.
Nanotechnology is still in its infancy in countries all over the world. Although a few
countries such as the United States, Japan, and Germany have begun to take foundation,
they are still under study, and the emergence of new theories and technologies is still in
the ascendant. China has made efforts to catch up with the advanced countries and the
research team is growing.

11, home appliances
The nano material multifunctional plastic made of nano material has the functions of
antibacterial, deodorizing, antiseptic, anti-aging, anti-ultraviolet, etc., and can be used as
an antibacterial deodorizing plastic in a refrigerator and an air conditioner casing.
12. Environmental protection
A uniquely functional nanofilm will appear in the field of environmental science. This
membrane is capable of detecting contamination from chemical and biological agents and
is capable of filtering these formulations to eliminate contamination.
13. Textile Industry
Adding nano-SiO2, nano-ZnO, and nano-SiO2 compound powder materials to
synthetic fiber resin, and by spinning and weaving, can be made into underwear and
clothing for sterilization, mildew proof, deodorization and anti-ultraviolet radiation, and can
be used for manufacturing antibacterial Underwear and supplies can produce functional
fibers that are resistant to ultraviolet radiation that meet the requirements of the defense
industry.
14. Machinery Industry
The use of nano-material technology to metal surface nano-powder coating of key
mechanical components can improve the wear resistance, hardness and service life of
mechanical equipment.
New material
The Nano New Material Formula is a project to create new nanomaterials by directly
ordering atoms and molecules within a space of 100 nanometers. Nano-new materials
and this field are the starting point for modern power and modern technological innovation.
The discovery of new laws and principles and the creation of new ideas give basic science
a new opportunity, which will become an important new driving force for reform in many
fields. The nano-newmaterial formulation has a lot of peculiar properties due to the small
size of SAIZU. In 1988, Baibich et al. found that the magnetoresistance change rate
reached 50% in nano Fe/Cr MS. It is one level larger than the average ME, and it is
negative. It is the same as GMR. . Giant ME was also found in nanosystems, tunnel
junctions and Perovskite structures, particle membranes. The Perovskite structure was

discovered in 1993 and has a very large ME called CMR. The TMR is found in the tunnel
junction.
Material classification
Nanomaterials can be roughly classified into four types: nano powder, nano fiber,
nano film, and nano block. Among them, nano-powder has the longest development time
and the most mature technology, which is the basis for the production of other three types
of products.
Nanoceramic
The nano-ceramic materials developed by using nanotechnology are modified by
using nano-powders, by adding or generating nano-sized particles, whiskers, wafer fibers,
etc. to the ceramics, so that the grains, grain boundaries and between them The
combination reaches the nano level, which greatly increases the strength, toughness and
superplasticity of the material. It overcomes many of the deficiencies of engineering
ceramics and has an important impact on the mechanical, electrical, thermal, and
magneto-optical properties of materials, opening up new fields for the replacement of
engineering ceramics.
With the wide application of nanotechnology, nano-ceramics have emerged, hoping
to overcome this.
The brittleness of ceramic materials gives ceramics a metal-like flexibility and
processability.
British materials scientist Cahn pointed out that nanoceramics is a strategic way to
solve the brittleness of ceramics. Nano-high temperature ceramic powder coating material
is a material that forms a high temperature resistant ceramic coating by chemical reaction.
Nano powder
Also known as ultrafine powder or ultrafine powder, generally refers to a powder or
granule with a particle size below 100 nm, which is a solid particulate material in an
intermediate state between atoms, molecules and macroscopic objects. Can be used for:
high density magnetic recording materials; absorbing stealth materials; magnetic fluid
materials; radiation protection materials; single crystal silicon and precision optical device

polishing materials; microchip thermal conductive substrate and wiring materials;
microelectronic packaging materials; optoelectronic materials; Battery electrode material;
solar cell material; high-efficiency catalyst; high-efficiency combustion improver; sensitive
components; high-toughness ceramic material (non-cracking ceramics, used in ceramic
engines, etc.); human body repair materials; anti-cancer preparations.
Nanofibers.
Refers to a linear material with a diameter of nanometer scale and a large length. Can
be used for: micro-wires, micro-fibers (important components of future quantum
computers and photonic computers) materials; new laser or light-emitting diode materials.
The electrospinning method is a simple and easy method for preparing inorganic
nanofibers.
Nanofilm
Nanofilms are divided into granular membranes and dense membranes. The particle
film is a film in which the nanoparticles are stuck together with a very small gap in between.
A dense film refers to a film that is dense but has a grain size of nanometer. Can be used
for: gas catalysis (such as automotive exhaust gas treatment) materials; filter materials;
high-density magnetic recording materials; photosensitive materials; flat panel display
materials; superconducting materials.
Nano-block
The nano-block is a nano-grain material obtained by high-pressure molding or
controlling crystallization of a metal powder. The main uses are: ultra-high strength
materials; smart metal materials.
Preparation
(1) Evaporation coacervation under inert gas. The particles having a particle size of
1-100 nm having a clean surface are usually formed by high pressure, and the nano
ceramics also need to be sintered. Foreign nano-solid materials, including metals and
alloys, ceramics, ionic crystals, amorphous materials and semiconductors, have been
successfully developed by using the above-mentioned inert gas evaporation and vacuum

in-situ pressure methods. China has also successfully used this method to make
nanomaterials such as metals, semiconductors and ceramics.
(2) Chemical methods: 1 hydrothermal method, including hydrothermal precipitation,
synthesis, decomposition and crystallization, suitable for the preparation of nano-oxides; 2
hydrolysis methods, including sol-gel method, solvent evaporation decomposition method,
latex method and evaporation separation Lawand so on.
(3) Comprehensive method. A preparation method formed by combining a physical
vapor phase method and a chemical deposition method. Others generally include ball
milling processing and jet processing.
Research results
The potential importance of nanotechnology as an emerging science and technology
with the most potential for market application is undoubted. Some developed countries
have invested a lot of money in research work. For example, the United States first
established the Nano Research Center, and the Japanese Department of Education and
Literature has listed nanotechnology as one of the four major research and development
projects in materials science. In Germany, with the University of Hamburg and the
University of Mainz as the Center for Nanotechnology Research, the government
contributes $65 million annually to support microsystem research. In China, many
research institutes and universities have also organized scientific research forces to carry
out research work on nanotechnology, and have achieved certain research results, mainly
as follows:
The synthesis of directional carbon nanotube arrays was completed by the
researcher of the Institute of Physics, Chinese Academy of Sciences. They used a
chemical vapor phase method to efficiently prepare carbon nanotubes with a pore size of
about 20 nm and a length of about 100 μm. A nanotube array was thus prepared with an
area of 3 mm x 3 mm and a spacing of 100 microns between the carbon nanotubes.
The preparation of gallium nitride nanorods was completed by Professor Fan
Shoushan of Tsinghua University. For the first time, they used carbon nanotubes to
prepare semiconductor gallium nitride one-dimensional nanorods with a diameter of 3 to
40 nanometers and a length of micron, and proposed the concept of carbon nanotubes
limiting reaction. In cooperation with Prof. Dai Hongjie from Stanford University, the
self-organized growth of carbon nanotube arrays on silicon substrates was achieved for
the first time in the world.

Quasi-one-dimensional nanowires and nano-cables were completed by Zhang Lide,
a researcher at the Institute of Solid State Physics, Chinese Academy of Sciences. They
used the new technologies such as carbothermal reduction, sol-gel soft chemistry and
nanodroplet epitaxy to synthesize SiO2 nano-cables of carbonized niobium nanowire
outer insulation insulators for the first time.
website：http://www.metal-oxide-materials.com/
The nano-diamond was prepared by catalytic pyrolysis and was completed by Qian
Yitai of Shandong University. They used catalytic pyrolysis to react carbon tetrachloride
with sodium to prepare diamond nanopowders.
However, compared with the advanced technology of developed countries, we still
have a big gap. The German Ministry of Science and Technology has predicted the future
market potential of nanotechnology: they believe that by 2000, the market capacity of
nanostructured devices will reach $637.5 billion, and the market capacity of nanopowders,
nanocomposite ceramics and other nanocomposites will reach 545.7 billion. In the US
dollar, the market capacity of nano-processing technology will reach 44.2 billion US
dollars, and the market capacity of nano-materials evaluation technology will reach 2.72
billion US dollars. And predict that the market's breakthroughs may be in the fields of
information, communication, environment and medicine.
In short, nanotechnology is becoming the focus of attention in the scientific and
technological circles of various countries, as the academician Qian Xuesen predicted:
"The structure of nanometers and below and nanometers will be the characteristic of the
next stage of technological development. It will be a technological revolution, and thus it
will be 21 Another industrial revolution of the century."
On October 19, 2011, the European Commission adopted a definition of
nanomaterials, which was later explained. According to the definition of the European
Commission, a nanomaterial is a powdery or agglomerate natural or artificial material
composed of elementary particles, one or more three-dimensional dimensions of which
are between 1 nm and 100 nm, and this The total number of elementary particles
accounts for more than 50% of the total number of particles of the entire material.
1 nanometer is equal to one billionth of a meter. At the nanoscale, some materials
have many special features. Nanomaterials have been widely used in people's work and
life.

In the definition of nanomaterials adopted by the European Commission, why is the
defined basic particle size between 1 nm and 100 nm? The European Commission
believes that the basic constituent particles of most of the known nanomaterials are within
this range, of course, materials beyond this range may also have the characteristics of
nanomaterials. This provision is intended to make the standard clear.
Why do the total number of basic particles of nanomaterials require more than 50% of
the total number of particles in the entire material? The European Commission believes
that too low a nanoparticle ratio will overwhelm the nanometer properties of the entire
material, and 50% is a suitable ratio. In addition, the use of the proportion of nanoparticles
rather than the mass ratio as a measure of nanomaterials, can better reflect the
characteristics of nanomaterials. Because some nanomaterials have very low density,
they have been able to show significant nanomaterial characteristics in the case of small
mass ratios.
Why do nanomaterials include natural materials? The European Commission
believes that nanomaterials should be defined by the size of the basic constituent particles,
whether natural or man-made. In fact, some natural materials also have the
characteristics of artificial nanomaterials.
Why exclude materials with nanostructures from nanomaterials? The European
Commission believes that although this material also has the characteristics of
nanomaterials, it is not yet possible to clearly define the nanostructures and thus is not
operational.
Why are products containing nanomaterials not nanomaterials? The European
Commission believes that nanomaterials are a mixture of raw materials or raw materials.
When it is made with other materials, it has formed new materials with other materials, so
the products produced are no longer nanomaterials.
However, the European Commission also acknowledged that this definition is still
incomplete and therefore decided to revise this definition in 2014 based on the actual
implementation of the development of science and technology and the definition.
Five major effects
Volume effect

When the size of the nanoparticles is equivalent to or less than the De Broglie wave
of the conduction electrons, the periodic boundary conditions will be destroyed, and the
magnetic, internal pressure, light absorption, thermal resistance, chemical activity,
catalytic properties, and melting point are all more common than ordinary particles. A big
change, this is the volume effect of nanoparticles. The following aspects of nanoparticle
effects and their multifaceted applications are based on its volumetric effects. For
example, the melting point of nanoparticles can be much lower than that of bulk bulk. This
property provides a new process for the powder metallurgy industry; by using the
properties of plasmon resonance frequency shift with particle size change, the particle
size can be changed, the displacement of the absorption can be controlled, and A
bandwidth microwave absorbing nanomaterial for electromagnetic shielding, stealth
aircraft, and the like.
Surface effect
The surface effect refers to a change in properties caused by a sharp increase in the
ratio of the surface atom to the total atomic number of the nanoparticle as the particle
diameter becomes smaller. Table 9-2 shows the relationship between nanoparticle size
and surface atomic number.
Table 1 Relationship between nanoparticle size and surface atom number
Particle size (nm) contains atoms
(a)
Particle size (nm) contains atoms
(a)
Particle size
(nm) contains
atoms (a)
20 2.5X10^5 10
10 3.0X10^4 20
5 4.0X10^3 40
2 2.5X10^2 80
1 30 99
As can be seen from the table, as the particle size decreases, the number of surface
atoms increases rapidly. In addition, as the particle size decreases, the surface area and
surface energy of the nanoparticles increase rapidly. This is mainly because the smaller
the particle size, the more atoms are on the surface. The crystal field environment and
binding energy of surface atoms are different from those of internal atoms. There are
many adjacent atoms around the surface atoms, many dangling bonds, unsaturated

properties, easy to be stabilized by other atoms, and thus exhibit great chemical and
catalytic activity.
Quantum size
When the particle size drops to a certain value, the phenomenon that the electron
energy level close to the Fermi level changes from the quasi-continuous level to the
discrete level is called the quantum size effect. Kubo uses an electronic model to
determine the energy level spacing of metal ultrafine particles: 4Ef/3N
Where Ef is the Fermi potential energy and N is the number of atoms in the particle.
The N of the macroscopic object tends to be infinite, so the energy level spacing tends to
zero. Due to the limited number of atoms and the small value of N, the nanoparticles have
a certain value, that is, the energy level is split. The electronic state of a semiconductor
nanoparticle transitions from a continuous energy band of a bulk phase material to a level
having a discrete structure as the size decreases, and the absorption spectrum is
transformed from a broad absorption band having no structure to a structure having
absorption characteristics. The volatility of electrons in discrete quantized energy levels in
nanoparticles leads to a range of properties of the nanoparticles, such as high optical
nonlinearities, specific catalytic and photocatalytic properties.
Quantum tunnel
The ability of microscopic particles to have a barrier through it is called tunneling. It
has been found that some macroscopic quantities, such as the magnetization of
microparticles, the magnetic flux of quantum coherent devices, and the charge, also have
tunneling effects, which can change across the barrier of the macroscopic system, so
called macroscopic quantum tunneling. This concept can be used to qualitatively explain
that ultrafine nickel particles remain superparamagnetic at low temperatures.
Dielectric limit
The dielectric confinement effects of nanoparticles are less noticeable. In actual
samples, the particles are surrounded by media such as air, polymers, glass, and solvents,
which typically have lower refractive indices than inorganic semiconductors. When the
light is irradiated, the interface is generated due to the difference in refractive index, and
the field intensity of the region adjacent to the surface of the nano-semiconductor, the
surface of the nano-semiconductor or even the inside of the nano-particle is larger than

that of the irradiated light. This local field strength effect has a direct impact on the
photophysical and nonlinear optical properties of semiconductor nanoparticles. For
inorganic-organic hybrid materials and photocatalytic materials used in heterogeneous
reaction systems, the dielectric confine ment effect has an important influence on the
reaction process and kinetics.
The above small size effect, surface effect, quantum size effect, macroscopic
quantum tunneling effect and dielectric confinement should be the basic characteristics of
nanoparticles and nanosolids. This series of effects leads to the melting point, vapor
pressure and optical properties of nanomaterials. Many physical and chemical aspects
such as chemical reactivity, magnetic properties, superconductivity and plastic
deformation show special properties. It gives nanoparticles and nanosolids many singular
physical and chemical properties.
Status quo
Applied research on basic theory of nanotechnology and development of new
materials has been rapidly developed, and has been widely used in traditional materials,
medical equipment, electronic equipment, paints and other industries. In terms of
industrialization development, in addition to the initial production of nano-powder
materials in a few countries such as the United States, Japan, and China,
nano-biomaterials, nano-electronic device materials, and nano-medical diagnostic
materials are still in the development stage. In 2010, the global nano-new materials
market reached US$2.23 billion, with an annual growth rate of 14.8%. In the next few
years, with the increasing investment in nanotechnology application research, the
industrialization process of nano-new materials will be greatly accelerated, and the market
scale will increase in volume. Nano-calcium carbonate, nano-zinc oxide, nano-silica and
other products in nano-powder materials have formed a certain market scale;
nano-ceramic materials, nano-textile materials, nano-modified coatings and other
materials have been widely used in nano-powder materials. The development was
successful, and the industrial production was initially realized. The application of
nano-powder particles in medical diagnostic preparations and microelectronics is stepping
up from the experimental research results to the industrial production of products.
Two-dimensional nano

Australian scientists have developed a new two-dimensional nanomaterial made of
molybdenum oxide crystal, which may revolutionize the electronics industry and make the
word "nano" no longer remain a marketing concept. In materials science, crystal films with
a thickness of nanometers are generally considered to be two-dimensional, that is, only
long and wide, and the thickness is negligible, called two-dimensional nanomaterials. The
newly developed material is only 11 nanometers thick and has a unique property in which
electrons can move at very high speeds. Scientists say they are inspired by another
wonderful new material, graphene. Graphene is a single-layer carbon atom network, the
thinnest material known to man, in which electrons can also move at high speed. However,
graphene lacks an energy gap, and transistors fabricated therewith cannot achieve
current switching. The molybdenum oxide material itself has an energy gap, and when it is
made into a graphene-like sheet, it supports both high-speed movement of electrons and
its semiconductor characteristics are suitable for manufacturing transistors.
Scientists say that inside new materials, electrons are rarely scattered due to
"roadblocks" and can move smoothly and quickly. With this new material, you can develop
smaller electronic components and products with faster data transfer speeds, such as
tablets that perform as well as desktop computers. The performance of electronic
products depends on the ability of semiconductor integration. In the past few decades,
technological advances have greatly reduced the size of transistors, and the performance
of silicon chips has increased tens of thousands of times, bringing the information
technology revolution. However, limited by the nature of the silicon material itself,
traditional semiconductor technology has reached its limit. Scientists are actively looking
for a new generation of semiconductor core materials. The research team has used
nanomaterials to create nanoscale transistors. They expect that if accepted by the
electronics industry, molybdenum oxide may become the standard material for electronic
products within five to seven years. Related papers were published in the January 4th
issue of Advanced Materials.
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