7440-21-3
Silicon
CAS: 7440-21-3
Molecular Formula: H4Si
7440-21-3 - Names and Identifiers
| Name | Silicon |
| Synonyms | Silicon silicium SIMP AX10 SIMP AX05 Silica flour Siliconwafer silicon,powder Silicon powder SiliconchipsNmm SiliconpowderNmesh Silicon (low oxygen) SiliconrandompiecesNcm Siliconwaferorientation Silicon Monocrystalline siliconpowder,amorphous Silicon solution 1000 ppm Silicon (3 oxygen levels) silicon coating quality balzers |
| CAS | 7440-21-3 |
| EINECS | 231-130-8 |
| InChI | InChI=1/Si |
| InChIKey | BLRPTPMANUNPDV-UHFFFAOYSA-N |
7440-21-3 - Physico-chemical Properties
| Molecular Formula | H4Si |
| Molar Mass | 32.12 |
| Density | 2.33g/mLat 25°C(lit.) |
| Melting Point | 1410°C(lit.) |
| Boling Point | 2355°C(lit.) |
| Water Solubility | INSOLUBLE |
| Vapor Presure | 54300mmHg at 25°C |
| Appearance | powder |
| Specific Gravity | 2.42 |
| Color | White |
| Odor | Odorless |
| Exposure Limit | ACGIH: TWA 2.5 mg/m3NIOSH: IDLH 250 mg/m3; TWA 2.5 mg/m3 |
| Merck | 13,8565 |
| PH | 13.5 (H2O, 20°C) |
| Storage Condition | Flammables area |
| Stability | Stable. Fine powder is highly flammable. Incompatible with oxidizing agents, bases, carbonates, alkali metals, lead and aluminium oxides, halogens, carbides, formic acid. |
| Sensitive | Air Sensitive |
| Physical and Chemical Properties | Crystals with gray metallic luster. |
| Use | Mainly used for the production of polycrystalline silicon, single crystal silicon, silicon aluminum alloy and silicon steel alloy compounds |
7440-21-3 - Risk and Safety
| Risk Codes | 11 - Highly Flammable |
| Safety Description | S26 - In case of contact with eyes, rinse immediately with plenty of water and seek medical advice. S36/37 - Wear suitable protective clothing and gloves. S45 - In case of accident or if you feel unwell, seek medical advice immediately (show the label whenever possible.) S7/9 - S33 - Take precautionary measures against static discharges. S16 - Keep away from sources of ignition. S36 - Wear suitable protective clothing. |
| UN IDs | UN 2922 8/PG 2 |
| WGK Germany | 2 |
| RTECS | VW0400000 |
| TSCA | Yes |
| HS Code | 3822 00 00 |
| Hazard Class | 4.1 |
| Packing Group | III |
7440-21-3 - Upstream Downstream Industry
| Raw Materials | Coke(coal) Calcium carbonate |
7440-21-3 - Nature
Open Data Verified Data
crystalline silicon is steel gray and amorphous silicon is black. Non-toxic, tasteless. d2.33; Melting point 1410 ℃; Average heat capacity (16~100 ℃)0. 1774cal/(g -℃). Crystalline silicon belongs to the atomic crystal, hard and glossy, is a typical semiconductor. At room temperature, in addition to hydrogen fluoride, it is difficult to react with other substances, insoluble in water, nitric acid and hydrochloric acid, soluble in hydrofluoric acid and alkali. At high temperatures can be combined with oxygen and other elements. It has the characteristics of high hardness, no water absorption, heat resistance, acid resistance, wear resistance and aging resistance. Silicon is widely distributed in nature, containing about 27.6% in the Earth's crust. It mainly exists in the form of silica and silicate.
Last Update：2024-01-02 23:10:35
7440-21-3 - Preparation Method
Open Data Verified Data
reduction is carried out by mixing silica having an SiO2 content of about 95% with Coke having a small amount of ash and heating to a temperature of about 1900 °c. The purity of the silicon obtained by this method is 97% to 98%, which is called metallic silicon. After the metal silicon is melted, recrystallization is carried out, and impurities are removed with an acid to obtain a metal Silicon having a purity of 99.7% to 99.8%. If it is to be made into silicon for semiconductor, it should be converted into a liquid or gas form that is easy to purify, and then the polycrystalline silicon is obtained by distillation and decomposition. If high purity silicon is required, further purification is required.
Last Update：2022-01-01 09:06:58
7440-21-3 - Use
Open Data Verified Data
mainly used in semiconductors, alloys, silicone polymer materials. High purity single crystal silicon is an important semiconductor material. Used as a diode, transistor, Thyristor and a variety of integrated circuit materials. It is also a promising material in the development of energy resources, and can be used to manufacture solar cells and the like. The ceramic and metal mixed sintering, made of metal ceramic composite material, high temperature resistance, rich toughness, can be cut, a collection of the advantages of metal and ceramic, is an important material of metal ceramic, space navigation. The glass fiber with high transparency made of pure silica has high optical fiber communication capacity, is free from electrical and magnetic interference, and has high confidentiality, and can be used for optical fiber communication. Silicon organic compounds can be used as plastics, coatings, etc., have been widely used.
Last Update：2022-01-01 09:06:58
7440-21-3 - Safety
Open Data Verified Data
rat oral LDso:3160mg/kg. Inhalation of high concentrations causes mild irritation of the respiratory tract, entering the eye as a foreign body irritating. Silicon powder with calcium, cesium carbide, chlorine, fluoride drill, fluorine, iodine trifluoride, manganese trifluoride, rubidium carbide, silver fluoride, potassium sodium alloy reaction. Dust in the flame or contact with the oxidant reaction, there is a moderate degree of risk. Store in a cool, dry, well-ventilated warehouse. Keep away from fire and heat source. Packaging is required to be sealed and not to be in contact with air. Should be stored separately from the oxidant, etc., should not be mixed storage.
Last Update：2022-01-01 09:06:59
7440-21-3 - Reference Information
| crystal Structure | Cubic, Diamond Structure - Space Group Fd3m |
| NIST chemical information | information provided by: webbook.nist.gov (external link) |
| EPA chemical substance information | information provided by: ofmpeb.epa.gov (external link) |
| Introduction | the chemical element symbol of silicon is Si, and the atomic number is 14. It is a hard and brittle crystalline solid with a blue-gray metallic luster and is a tetravalent metalloid and semiconductor. It is a member of group 14 of the periodic table: carbon is above it; Germanium, tin and lead are below it. It was relatively unresponsive. Because of its high chemical affinity for oxygen, it was not until 1823 that jönsjakob Berzelius was first able to prepare oxygen and characterize it in pure form. Its melting point and boiling point of 1414°C and 3265°C, respectively, is the second highest of all metalloids and non-metals, second only to boron. Silicon is the eighth most common element in the universe in terms of mass, but rarely appears in the crust as a pure element. It is widely distributed in dust, sand grains, planetary-like and planetary in various forms of silica (silicates) or silicates. More than 90% of the Earth's crust is a silicate mineral, making Silicon the second most abundant element in the Earth's crust (about 28% by mass), second only to oxygen. |
| History of discovery | in 1800 David considered silica as a chemical compound rather than an element. Gay Lussac and Thenard obtained very impure amorphous silicon in 1809 by passing Silicon tetrafluoride through heated potassium. Berzelius corrected this finding in 1823 and used the same method to produce high purity elemental silicon. He also obtained silicon by heating potassium fluosilicate with potassium metal. De Ville produced crystalline silicon by electrolyzing a molten mixture of impure sodium chloride aluminum containing 10% silicon and a small amount of aluminum in 1854. |
| Source | silicon is present in the sun and constant stars, and is a major component of a class of meteorites called "meteorites. It is also a component of ilmenite, a natural glass of uncertain origin. Natural silicon contains three isotopes. Twenty-four other radioisotopes were recognized. Silicon accounts for 25.7% of the weight of the Earth's crust and is the second most abundant element after oxygen. Silicon is not free in nature, but exists mainly in the form of oxides and silicates. Sand, quartz, Crystal, violet crystal, Onyx, fl stone, jade, and Opal are some of the forms that appear as oxides. Granite, hornblende, asbestos, feldspar, Clay Mica and so on are only a few of the many silicate minerals. Silicon is produced commercially by heating silicon dioxide and carbon in an electric furnace using a carbon electrode. Several other methods can be used to prepare the element. Amorphous silicon can be made into a brown powder that can be easily melted or vaporized. Crystalline silicon has a metallic luster and a light gray color. Silicon in the form of silica (SiO2) is the most abundant compound in the Earth's crust. As an element, silicon is second only to oxygen in concentration on Earth, but only seventh in the universe. Even so, silicon is still used as a standard (Si = 1) to estimate the abundance of all other elements in the universe. |
| Applications | In this electronic age, elemental silicon has some of the most important applications. One of the main applications is the computer chip. Single crystals of crystalline silicon are used in solid-state or semiconductor devices. High purity silicon doped with boron, phosphorus, arsenic and gallium and other trace elements, is one of the best semiconductors. They are used in transistors, power rectifiers, diodes and solar cells. Silicon rectifiers convert alternating current (AC) to direct current (DC) most efficiently. Hydrogenated amorphous silicon converts solar energy into electrical energy. Silicone (volatile) is used in the cream to enhance the protective ability of the product to prevent evaporation of moisture from the skin. Silicone Polyethers are mainly used in water-based skin care formulations and have improved softness, gloss and hand feel. Silicon can also be used as an alloy when mixed with iron, steel, copper, aluminum and bronze. When used in combination with steel, it can be made into excellent springs, suitable for various types of applications, including automobiles. |
| preparation | Elemental silicon is produced commercially by heating silica together with carbon (coke) in an electric furnace using a carbon electrode: siO2 C → Si CO2 The purity of the obtained product was about 96-98%. Repeated leaching resulted in approximately 99.7% of the purified product. Alternatively, the lower silicon is converted to its halide or halosilane and then reduced with a high-purity reducing agent. Ultrapure silicon for semiconductor applications can be fabricated by several methods. These processes include reduction of silicon tetrachloride with high purity zinc: SiCl4 2Zn → Si 2ZnCl2 or reduction of trichlorosilane with hydrogen using a silicon wire at a temperature of 1,150°C: siHCl3 H2 → Si 3HCl or heating silane or silicon tetraiodide to high temperature: SiH4 → Si 2H2SiI4 → Si 2I2 or by reduction of silicon tetrafluoride with sodium: siF4 4NaF → Si 4 NaF |
| toxicity | trichlorosilane is toxic to human body, its vapor has asphyxiating odor, strongly stimulating respiratory mucosa; Its hydrolysis product hydrogen chloride, silica is irritating to the lungs, and long-term inhalation can lead to anemia. The maximum allowable concentration of trichlorosilane is 1mg/m3. Production equipment should be closed, workshop ventilation should be good. Production personnel should wear anti-virus masks, closed glasses, wear work clothes and other labor protection articles to prevent contact with respiratory organs, eyes and skin. The poisoning should be immediately transferred to fresh air for artificial respiration, oxygen, injection of glucose and cardiac agents, and quickly sent to the hospital for treatment. |
| Use | is used as a raw material for the manufacture of monocrystalline silicon, and is also used in the electronics industry is a raw material for the manufacture of semiconductor silicon devices, for the manufacture of high-power rectifiers, high-power transistors, diodes, switching devices, etc. for the manufacture of discrete semiconductor devices, power devices, integrated circuits and epitaxial substrates. mainly used for making polysilicon, single crystal silicon, silicon aluminum alloy and silicon steel alloy, etc. used for making transistors, rectifiers and solar cells, also used for making high silicon cast iron, silicon steel, various organosilicon compounds and the like are used as raw materials for the preparation of single-crystal silicon. compounds mainly used for making polycrystalline silicon, single crystal silicon, silicon aluminum alloy and silicon steel alloy used for making alloy, organosilicon compound and silicon tetrachloride, etc., is an extremely important semiconductor material. |
| production method | trichlorosilane method the dried silicon powder is added to the synthesis furnace, chlorination reaction is carried out with dry hydrogen chloride gas at 280~330 ℃ in the presence of cuprous chloride catalyst. The reaction gas is separated by cyclone to remove impurities, and then the gaseous trichlorosilane is condensed into liquid with calcium chloride frozen brine, after distillation and condensation in a crude distillation column to remove high and low boilers, the refined trichlorosilane liquid is obtained by distillation and condensation in a rectification column. The purity reaches 7 "9" or more, the impurity content is less than 1 × 10-7, and the boron is required to be less than 0.5 × 10-9. The Purified trichlorosilane is sent to a reduction furnace made of stainless steel, and is reduced to silicon at 1050-1100 ° C. By using ultra-pure hydrogen as a reducing agent, and is deposited with a silicon mandrel as a carrier to obtain a polycrystalline silicon product. Its H2 C12 → 2HClS 3HCl → SiHC13 H2SiHCl3 H2 → Si 3HCl industrial production includes Crucible Czochralski method, suspension zone melting method and neutron transmutation doping method. The components of the equipment, the alloy quartz crucible, the Silicon polycrystal and the seed crystal were cleaned before the Czochralski. After the graphite is removed by crushing the silicon polycrystalline, the oil is removed by acetone, and then the chemical cleaning is carried out, the ion-free water is washed to neutral, and then the ultrasonic cleaning, infrared drying, mixing and doping are carried out, it is added into the alloy quartz crucible of the single crystal furnace, and then subjected to vacuum pumping and melting. Under the circulating argon atmosphere, the crystal is artificially introduced to the shoulder and the end. In the process of equal diameter growth of crystal, the power should be appropriately adjusted according to the situation to obtain products with uniform diameter. After testing and weighing, the finished silicon single crystal product is prepared. The equipment and raw materials are cleaned by the suspension zone melting method, and the silicon polycrystalline is cut off. After grinding, the oil is removed with acetone, and chemical cleaning is carried out, dosing and doping, furnace, vacuum or argon. Zone melting purification of single crystals was performed by high-frequency heating under argon. The processes of preheating, Crystal insertion, shoulder release, equal diameter, and finishing shall be controlled manually. After testing and weighing, the finished silicon single crystal was obtained. |
| spontaneous combustion temperature | 780°C |
| toxic substance data | information provided by: pubchem.ncbi.nlm.nih.gov (external link) |
Last Update：2024-04-09 21:04:16
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