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Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula SiO 2, commonly found in nature as quartz. [5] [6] In many parts of the world, silica is the major constituent of sand. Silica is one of the most complex and abundant families of materials, existing as a compound of several minerals and as a synthetic product.
Quartz is a hard, crystalline mineral composed of silica (silicon dioxide).The atoms are linked in a continuous framework of SiO 4 silicon–oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical formula of SiO 2.
Silicalite is an inorganic compound with the formula SiO 2. It is one of several forms of silicon dioxide. It is a white solid. It consists of tetrahedral silicon centers and two-coordinate oxides. It is prepared by hydrothermal reaction using tetrapropylammonium hydroxide followed by calcining to remove residual ammonium salts.
The general formula is (Si x O 3x) 2x−, where one or more silicon atoms can be replaced by other 4-coordinated atom(s). The silicon:oxygen ratio is 1:3. Double rings have the formula (Si 2x O 5x) 2x− or a 2:5 ratio. The Nickel–Strunz classification is 09.C. Possible ring sizes include:
Silica gel, also referred to as silicon dioxide or synthetic amorphous silica (SAS), is listed by the FDA in the United States as generally recognized as safe (GRAS), meaning it can be added to food products without needing approval. Silica is allowed to be added to food in the US at up to 2% as permitted under 21 CFR 172.480.
Aluminium silicate is a type of fibrous material made of aluminium oxide and silicon dioxide, (such materials are also called aluminosilicate fibres). These are glassy solid solutions rather than chemical compounds. The compositions are often described in terms of % weight of alumina, Al 2 O 3 and silica, SiO 2. Temperature resistance increases ...
Precipitated silica is an amorphous form of silica (silicon dioxide, SiO 2); it is a white, powdery material. Precipitated silica is produced by precipitation from a solution containing silicate salts. The three main classes of amorphous silica are pyrogenic silica, precipitated silica and silica gel.
Liquid silicon dioxide (colloidal silica) is used as a wine and juice fining agent. Absorbent; Colloidal silica is used in concrete densifiers and polished concrete. In manufacturing Quantum dots, small semi-conductors used in various scientific research settings. Reduced porosity and increased protection from alkali-silica reaction (ASR). [2]