The earth's crust contains up to 25.8% of the element silicon, which provides an inexhaustible source for the production of monocrystalline silicon. Since silicon is one of the most abundant elements in the earth's crust, the advantage of reserves is one of the reasons why silicon is the main material for photovoltaics, a product destined for the mass market like solar cells.
Chinese name
Silicon wafers
State
Integrates more than 40 million transistors
Principle
Microelectronics
Fields
Aeronautics, aerospace, industry, agriculture
Already able to integrate more than 40 million transistors. What fine engineering this is! It is the culmination of a concerted multidisciplinary effort and another milestone in the advancement of science and technology.
Microelectronics technology is quietly into the aviation, aerospace, industry, agriculture and defense, but also quietly into every family. The huge "magic" of a small silicon chip is simply unimaginable to our predecessors.
Applications
Silicon chips are known as the "magic calculator", with amazing computing power. No matter how complex mathematical problems, physical problems and engineering problems, no matter how big the workload of the calculation, as long as the staff through the computer keyboard to tell it the problem, and under the idea of solving the problem and instructions, the computer will be able to tell you the answer in a very short period of time. In this way, those manual calculations need to spend years, decades of time, the computer may only need a few minutes to solve the problem. Even some problems that human beings can't calculate the result, the computer can tell you the answer very quickly.
The chip is also a modern miniature "knowledge base", which has a fabulous storage capacity, and can fit a 24-volume Encyclopedia Britannica on a silicon chip the size of a pinhead. Now the world's books and magazines have more than 30 million kinds, and every year to increase more than 50 million kinds, can be described as a vast ocean. German futurist Beinhauer pointed out, "Today's scientists, even if they work all day and all night, can only read 5% of all the publications in their specialty." What is the way out? The only way out is for the various library and information centers to be responsible for putting all kinds of information into silicon memory and connecting it into a network with communication lines. In this way, scientific and technological personnel to find some kind of information and data, as long as sitting in the office to operate the computer keyboard, immediately in the computer's fluorescent screen will display the content of the query.
Microelectronic chips into the field of medicine, so that the ancient medical youthful glow, for the cause of human health care continue to create brilliant.
The microelectronic chip of the "magic" also lies in that it can make the blind people back to the blind, deaf people back to the deaf, mute people speak and prosthetic limbs can move, so that tens of millions of people around the world with disabilities to get the light and hope.
Microelectronics technology in aerospace, defense and industrial automation in the incomparable power is a well-known fact. Under the control of large-scale electronic computers, unmanned aircraft can fly freely in the blue sky; artificial satellites, spaceships, space shuttles can be accurately lifted off, flight, positioning, and automatically send back to the ground a variety of information. Under the command of electronic computers, artillery, missiles can be fired without error, accurately hitting the target, and can even accurately hit the fast-moving targets in the air, including the enemy's missiles in flight. The extensive use of computers and various sensing technologies in industry can save manpower, improve the degree of automation and processing accuracy, and greatly improve labor productivity. Robots have appeared in many industrial fields. They not only work hard, but also work fast, high precision, and even in some high temperature, underwater and dangerous sections of the work can also charge forward, and intelligent robots have begun to show extraordinary hands. Effective organization and coordination and a strong sense of shooting are all applauded. It defeated the world's number one grandmaster of chess. Its brilliant performance shows that intelligent computers have developed to a brand new stage.
Silicon dioxide, an inorganic compound with the chemical formula SiO2, forms crystalline silicon dioxide by the long-range ordered arrangement of silicon atoms and oxygen atoms, and amorphous silicon dioxide by the short-range ordered or long-range disordered arrangement.
Silicon dioxide crystals, silicon atoms are located in the center of the orthotetrahedron, four oxygen atoms are located in the four top corners of the orthotetrahedron, many of these tetrahedrons and through the top corners of the oxygen atoms are connected to each oxygen atom for the two tetrahedrons **** there, that is, each oxygen atom is combined with two silicon atoms.
The simplest form of silicon dioxide is SiO2, but SiO2 does not represent a simple molecule (it only represents the ratio of the number of atoms of silicon and oxygen in a silicon dioxide crystal). Pure, natural silicon dioxide crystals are a hard, brittle, insoluble, colorless, transparent solid that is commonly used in the manufacture of optical instruments, among other things [1].
Chinese name
Silicon dioxide
External name
Silicon dioxide
Chemical formula
SiO2 [11]
Molecular weight
60.084
CAS registry number
14808-60-7
Silicon dioxide [èr yǎng huà guī]
Inorganic compounds
Science China? |? This entry was reviewed by the "Popular Science China" Science Encyclopedia Entry Writing and Application Project
Reviewed by? Bao Shenxu
Silicon dioxide is an inorganic compound with the chemical formula SiO2, in which silicon atoms and oxygen atoms are arranged in a long-range orderly fashion to form crystalline silicon dioxide, and in a short-range orderly or long-range disordered fashion to form amorphous silicon dioxide.
Silicon dioxide crystals, silicon atoms are located in the center of the orthotetrahedron, four oxygen atoms are located in the four top corners of the orthotetrahedron, many of these tetrahedrons and through the top corners of the oxygen atoms are connected to each oxygen atom for the two tetrahedrons **** there, that is, each oxygen atom is combined with two silicon atoms.
The simplest form of silicon dioxide is SiO2, but SiO2 does not represent a simple molecule (it only represents the ratio of the number of atoms of silicon and oxygen in a silicon dioxide crystal). Pure, natural silicon dioxide crystals are a hard, brittle, insoluble, colorless, transparent solid that is commonly used in the manufacture of optical instruments, among other things [1].
Chinese name
Silicon dioxide
Foreign name
Silicon dioxide
Chemical formula
SiO2[11]
Molecular weight
60.084
CAS registry number
14808-60-7 [11]
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Silicon dioxide molecular formula, chemical properties
Read product number Physical and chemical
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Physical and chemical properties Preparation method Substance Introduction Substance Structure Mineral Classification Substance Usage Consumption Suggestion Health Hazard
Physical and chemical properties
Physical properties
Crystalline Silicon Dioxide
Density: 2.2 g/cm3
Melting point: 1723℃
Boiling point: 2230℃
Refractive index: 1.6
Changes when heated: melts with strong alkali when heated to produce silicate
Solubility: insoluble in water, can interact with HF to produce gaseous SiF4
Chemical properties
Chemical properties are relatively stable. Does not react with water. It has high fire resistance, high temperature resistance, low coefficient of thermal expansion, high insulation, corrosion resistance, piezoelectric effect, resonance effect and its unique optical properties. [11] It is an acidic oxide and does not react with normal acids. Hydrofluoric acid reacts with silicon dioxide to form gaseous silicon tetrafluoride. It reacts with hot concentrated alkali solutions or melted alkalis to form silicates and water. React with various metal oxides at high temperature to form silicates. Silicon dioxide is inactive, it does not interact with halogens other than fluorine, hydrogen fluoride, hydrogen halide, sulfuric acid, nitric acid, perchloric acid (except hot concentrated phosphoric acid). [2]
Common concentrated phosphoric acid (or pyrophosphoric acid) at high temperatures can corrode silicon dioxide, generating heteropolyacid, high temperature fused borate or boronic anhydride can also corrode silicon dioxide, in view of the nature of this borate can be used for ceramics firing in the flux, in addition to the hydrogen fluoride can also make the silicon dioxide can be dissolved in the acid, generating easily soluble in water fluorosilicic acid. [2]
SiO2+4HF=SiF4↑+2H2O[2]
6HF+SiO2=H2SiF6+2H2O[2]
SiO2+2NaOH (concentrated)=Na2SiO3+H2O[2]
SiO2+Na2CO3=Na2SiO3+CO2↑[2 ] (high temperature)
SiO2+CaO=CaSiO3[2]
SiO2+2C=2CO↑+Si[2]
Method of preparation
Preparation method
Amorphous silicon dioxide
Amorphous silicon dioxide preparation consists of five steps, which are the preparation of silica mass gel, granulation process, sintering process , cleaning process, and drying process [3].
1: Preparation of silica gel
Silica gel is generated by hydrolysis of silicon tetrachloride, or by hydrolysis of organosilicon compounds such as tetramethoxysilane, or by using fumed silica to generate silica gel [3].
2: Granulation process
The silica gel is dried into a dry powder by drying the silica, and the dry powder is crushed and then graded, thereby obtaining a silica powder of a desired average particle size [3].
3: Sintering process
The silica powder obtained in the granulation process is sintered at a temperature of 800° C. to 1,450° C. In the spheronization process utilizing a thermal plasma, the silica powder obtained in the sintering process is put into the plasma torch introducing argon at a predetermined flow rate and generating plasma at a predetermined high-frequency output power at a predetermined supply speed, and is sintered at a temperature of from 2000° C. to the boiling point of the silica is heated and melted [3].
4: Cleaning process
Removal of micronized powder [3] adhering to the surface of the spheroidized silica powder after the spheroidization process described above.
5: Drying process
Drying the silica powder [3] after the above cleaning process.
Preparation method of crystalline silica
The raw material containing silica (silica source), water, structural guide agent, alkali or acid are mixed uniformly according to a certain proportion and put into a pressure-resistant reactor to be sealed, and then the temperature is raised to 100-220°C, and the temperature is kept constant for 5 hours to 10 days, and the reactor is cooled down rapidly at the end of the reaction, and the reaction product is washed with water or dilute acid to a pH of 8-11, and dried to obtain the raw powder, and the powder is dried to obtain the raw powder. 11, drying to obtain the raw powder, raw powder or the product after adding binder molding is roasted and activated in muffle furnace or tube furnace [4].
Substance use
Silicon dioxide is the raw material for the manufacture of glass, quartz glass, water glass, optical fibers, important parts of the electronics industry, optical instruments, handicrafts and refractories, and is an important material for scientific research. [6]
When silicon dioxide crystallization is complete is crystal; silicon dioxide gelatinization and dehydration is agate; silicon dioxide water-containing colloid solidification becomes opal; silicon dioxide grains less than a few microns, it is composed of chalcedony, flint, secondary quartzite. Physical properties and chemical properties are very stable mineral resources, crystals belong to the tripartite crystal system of oxide minerals, that is, low-temperature quartz (α-quartz), is the quartz family of minerals in the widest distribution of a mineral species. Broad quartz also includes high temperature quartz (β-quartz). Quartz lumps, also known as silica, are mainly used as a raw material for the production of quartz sand (also known as silica sand), as well as quartz refractories and for the firing of ferrosilicon. [7]
In addition, silica can also be used as a lubricant, is an excellent flow promoter, mainly as a lubricant, anti-adhesive, flow aids. It is especially suitable for the granulation of oils and extracts, and the granules made have good flowability and compressibility. It can also be used as flow aid in direct tablet pressing. As a disintegrating agent, it can greatly improve the fluidity of particles, increase the bulk density, increase the hardness of tablets, shorten the time of disintegration and improve the speed of drug dissolution. It can be used as internal drying agent in the manufacture of granules to enhance the stability of drugs. It can also be used as filtering agent, clarifying agent, defoaming agent and liquid preparation of suspending agent and thickening agent.