CAS 7631-86-9 Silicon dioxide Nanopowder - Materials / Alfa Chemistry

NAVIGATION

Silicon dioxide Nanopowder

PRICE INQUIRY

Catalog Number

ACM7631869-5

CAS Number

7631-86-9

Product Name

Silicon dioxide Nanopowder

Structure

Category

Nanopowders

Description

Transparent to gray, odorless powder. Irritating to the skin and eyes on contact. Inhalation will cause irritation in the respiratory tract. [Note: Amorphous silica is the non-crystalline form of SiO2.];PelletsLargeCrystals, OtherSolid, Liquid;DryPowder; Liquid;DryPowder; OtherSolid;DryPowder; DryPowder, Liquid; DryPowder, OtherSolid; Liquid; OtherSolid; PelletsLargeCrystals; WetSolid; WetSolid, Liquid;DryPowder; DryPowder, Liquid; DryPowder, PelletsLargeCrystals; OtherSolid; PelletsLargeCrystals;DryPowder; OtherSolid;DryPowder; DryPowder, Liquid; DryPowder, OtherSolid; DryPowder, OtherSolid, Liquid; DryPowder, PelletsLargeCrystals; DryPowder, PelletsLargeCrystals, Liquid; DryPowder, PelletsLargeCrystals, OtherSolid; DryPowder, PelletsLargeCrystals, WetSolid; DryPowder, WetSolid; Liquid; OtherSolid; PelletsLargeCrystals; PelletsLargeCrystals, OtherSolid; WetSolid; WetSolid, Liquid;PelletsLargeCrystals;White, fluffy powder or granules. Hygroscopic;Solid;FINE WHITE POWDER.;COLOURLESS OR WHITE CRYSTALS.;COLOURLESS WHITE CRYSTALS.;COLOURLESS OR WHITE CRYSTALS.;Solid;Transparent to gray, odorless powder. [Note: Amorphous silica is the non-crystalline form of SiO2.]

IUPAC Name

dioxosilane

Molecular Weight

60.084g/mol

Molecular Formula

(SiO2)n;SiO2;SiO2;SiO2;SiO2;SiO2;O2Si

Canonical SMILES

O=[Si]=O

InChI

InChI=1S/O2Si/c1-3-2

InChI Key

VYPSYNLAJGMNEJ-UHFFFAOYSA-N

Boiling Point

4046 °F at 760 mm Hg (NIOSH, 2016);4046 °F;2230 °C;>2200 °C;2230 °C;2230 °C;2230 °C;4046°F

Melting Point

3110 °F (NIOSH, 2016);Mp 1716-1736 °;3110 °F;1710 °C;1716-1736°C;1710 °C;1703 °C;1610 °C;1713 °C;3110°F

Purity

99%

Density

2.2 (NIOSH, 2016);2.2 @ 25 °C;2.6;2.3 g/cm³;2.3 g/cm³;2.6 g/m3;2.3 g/cm³;2.20

Solubility

Insoluble (NIOSH, 2016);Insoluble;Silica is rather poorly soluble in water although solubility is higher for the amorphous than for the crystalline morphologies. ... The external amorphous layer in quartz is more soluble than the crystalline underlying core.;AMORPHOUS IS SOL IN ALKALIES, ESP WHEN FINELY DIVIDED;Practically insoluble in water or acids. Dissolves readily in HF, forming silicon tetrafluoride.;Very slightly sol in alkali.;Soluble in hot potassium hydroxide and hot sodium hydroxide solutions. Insoluble in ethanol.;Silica is rather poorly soluble in water and solubility is lower for the crystalline than for the amorphous morphologies. ...Solubility increases with temperature and pH and is affected by the presence of trace metals. Particle size influences the rate of solubility.;The external amorphous layer in quartz (the Beilby layer) is more soluble than the crystalline underlying core.;Solubility in water: none;Solubility in water: none;Solubility in water: none;Solubility in water: none;Insoluble

Color/Form

Amorphous powder;Transparent to gray powder (Note: Amorphous silica is the non-crystalline form of O2Si). ... solid;Silica gel is a coherent, rigid, continuous three-dimensional network of spherical particles of colloidal microporous silica.;Transparent crystals

Complexity

18.3

Corrosivity

Non-corrosive

Covalently-Bonded Unit Count

EC Number

231-545-4;231-545-4;238-455-4;238-878-4;239-487-1;262-373-8;234-368-0;293-303-4;601-214-2;601-216-3;604-037-9;612-383-7;918-946-6;920-837-3;921-597-2

Exact Mass

59.966756g/mol

Formal Charge

Heavy Atom Count

ICSC Number

0248;0807;0808;0809

MeSH Entry Terms

380, Aerosil;Aerosil;Aerosil 380;Cristobalite;Dioxide, Silicon;G32, Quso;Quso G 32;Quso G-32;Quso G32;Silica;Silicon Dioxide;Tridymite

Monoisotopic Mass

59.966756g/mol

Odor

Odorless;Odorless

Other Experimental

Amorphous silca: pyrogenic (fumed) amorphous silica (112945-52-5, formerly under 7631-86-9); Precipitated silica, including silica gel (112926-00-8, previously under 7631-86-9; deleted CAS number 112945-53-6); Diatomaceous earth (uncalcined)(61790-53-2; deleted CAS numbers 53571-43-0; 77108-41-9, 61970-41-0, 37337-67-0; 56748-40-4; 54990-62-4; 54990-61-3; 57692-84-9; 81988-94-5; 67417-47-4; 39455-02-2; 54511-18-1; 37264-95-2; 50814-24-9; 73158-38-0; 12623-98-2; 55839-10-6; 51109-72-9; 68368-75-2; 67016-73-3; 12750-99-1; 64060-29-3; 39421-62-0; 37328-66-8; 11139-66-5; 57126-63-3; 29847-98-1); Vitreous silica, quartz glass, fused silica (60676-86-0; deleted CAS numbers 55126-05-1; 119573-97-6; 37224-35-4; 37224-34-3); Flux-calcined diatomaceous earth (68855-54-9);Opal is an amorphous hydrous silica that may contain cryptocrystalline cristobalite. Biogenic silica is defined as any silica originating in living matter (known sources include bacteria, fungi, diatoms, sponges and plants); the two most relevant biogenic silicas are those associated with fossilized diatoms and crop plants. Diatomaceous earths are the geological products of decayed unicellular organisms (algae) called diatoms. Vitreous silicas are volcanic glasses; lechaterlierites are nautral glasses produced by the fusion of siliceous material under the impact of meteorites. Fused silica is silica heated up to a liquid phase and cooled down without allowing it to crystallize. Pyrogenic or fumed silica is silica prepared by the combustion of a volatile silicon compound (usually SiCl(4)). Precipitated silica is silica precipitated from an aqueous solution. Colloidal silica is a stable dispersion of discrete, colloid-sized particles of amorphous silica in an aqueous solution. /Amorphous forms/;Commercial grades capable of withstanding temperatures up to 260-315 °C are supplied in the following mesh sizes: 3-8, 6-16, 14-20, 14-42, 28-200, and through 325. Noncombustible. /Silica gel/;In amorphous silica the different molecules are in a dissimilar spatial relationship one to another, with the result that there is no definite regular pattern between molecules some distance apart.;The solubility of the various phases of silicas is very complex and depends upon several factors. Solubility increases with temperature and pH and is affected by the presence of trace metals. Particle size influences the rate of solubility. /Silica/;Amorphous particles are less hydrophilic than crystalline particles;/Natural forms include alpha, beta quartz; alpha, beta1, beta2 tridymite; alpha, beta cristobalite, coesite; stishovite; moganite/.;/Synthetic forms include keatite; silica W; porosils (zeosils and clathrasils)/.;Silicon-oxygen tetrahedra (SiO4) are the basic units of... crystalline... forms. ...The three-dimensional framework of crystalline silicas is determined by the regular arrangement of the tetrehedra, which share each of their corners with another tetrahedron. Differences in the orientation and position of the tetrahedra create the differences in symmetry and cell parameters that give rise to the various polymorphs. In the case of quartz, the structural feature is a helix composed of tetrahedra along the c-axis. The helices have a repeat distance of three tetrahedra. The winding of the helices can be left- or right-handed, which results in the enantiomorphism of quartz crystals.;The crystal system for alpha-quartz is trigonal. /from table/;The crystal system for alpha-tridymite is orthorhombic. /from table/;The crystal system for alpha-cristobalite is tetragonal. /from table/;The crystal system for coesite is monoclinic. /from table/;The crystal system for stishovite is tetragonal. /from table/;Colorless crystals or white powder; odorless and tasteless; density: 2.2-2.6; soluble in molten alkai when finely divided and amorphous /Silicon dioxide/;Melts to glass at ordinary temps. Chemically resistant to most reagents. /Silica dioxide/;Occurs as hexagonal crystals: more commonly naturally in an anhedral massive form /alpha-Quartz/;Occurs as octahedral, rarely cubical, crystals; also in massive form. /alpha-Cristobalite/;Occurs as tabular pseudohexagonal crystals; also in massive form. /alpha-Tridymite/;Specific gravity: 2.2, MP: 1610 °C, BP: 2230 °C, Mohs Hardness: 7, Density: 2.635-2.660, Water solubility: insoluble, Color: colorless, white, or variable black, purple, green /alpha-Quartz/;Specific gravity: 2.32, Mohs Hardness: 6.5, Density: 2.33, Water solubility: insoluble, Color: colorless, white, or yellowish /alpha-Cristobalite/;Specific gravity: 2.26, MP: 1703 °C, Mohs Hardness: 7, Density: 2.26, Water solubility: insoluble, Color: colorless or white. /alpha-Tridymite/;Lowest coefficient of expansion by heat of any known substance; dissolves /in hydrofluoric acid/ forming the gas silicon tetrafluoride; slowly attacked by heating with concn phosphoric acid; crystallized forms of silica are scarcely attacked by alkalies, while amorphous is sol, esp when finely divided. /Silica dioxide/;White to light gray to pale buff powder. Insol in water, acids or dil alkalies. Capable of taking up and holding about four times its wt of water. /Infusorial earth/;Density = 2.20 g/cm; Refractive index = 1.459; Surface tension = 5.200 @ 298 K (calc); Thermal conductivity = 1.37 W/m-deg K at 298 deg K ; Heat of Formation = -903.2 kJ/mol at 298 deg K; Heat Capacity = 37.94 J/mol-deg K at 298 deg K; Dielectric Constant = 3.8 /Corning 7940 fused silica/;Colorless hexagonal crystals; Melting point: 867; Boiling point: 2950; Trans to tridymite; Density: 2.533 g/cu cm /beta Quartz/;White to reddish crystals /Crystalline silica-quartz/;White or colorless platelets or orthorhombic crystals formed from quartz at temperatures >870 °C /Crystalline silica-tridymite/;White, cubic-system crystals formed from quartz at temperatures above 1000 °C /Crystalline silica-cristabolite/;Combines with alkalies under suitable conditions to form silcates. /Silicon dioxide/;Density = 2.648 /alpha-Quartz/ /from table/;Density = 2.269 /alpha-Tridymite/ /from table/;Density = 2.318 /alpha-Cristobalite/ /from table/;Density = 2.909 /Coesite/ /from table/;Density = 4.287 /Stishovite/ /from table/;The surface areas of ground samples of crystalline... silica depend on the grinding procedure and vary between 0.1 and 10-15 sq m/g.;alpha-Quartz is stable over most of the temperatures and pressures that characterize the earth's crust. Tridymite and cristobalite are formed at higher temperatures, while coesite and stishovite are formed at higher pressure. The conversion from one crystalline structure to another requires the rupture of silicon-oxygen bonds and the reconstruction of new ones. This process requires a very high activation energy. Although alpha-quartz is the only silica phase stable under ambient conditions, other silica polymorphs, namely alpha-tridymite, alpha-cristobalite, coesite and stishovite, exist with metastability at the earth's surface. Their conversion to alpha-quartz under ambient conditions is, in fact, immeasurably slow. In contrast, the /interconversion of alpha and beta forms/ in quartz, tridymite and cristobalite requires only the rotation of silicon bonds; this can occur rapidly at the interconversion temperature. Consequently, only the alpha (low) forms can exist in ambient conditions.;The following polymorphs are obtained at high pressure: coesite, produced at 450-800 °C and at 38,000 atmospheres (3.8X10+6 kPa), found in rocks subjected to the impact of large meteorites; keatite, synthesized at 380-585 °C and 330-1,200 atmospheres (33-121X10+3 kPa), not commonly found in nature; and stishovite, synthesized at temperatures above 1,200 °C and at 130,000 atmospheres (13X10+6 kPa), detected in Meteor crater, Arizona, United States. These forms of silica are metastable under ambient conditions and can be converted into other polymorphs upon heating.;Conversion from the crystalline to amorphous form may occur by grinding or by melting and rapidly cooling down the melt. ...Conversely, crystallization into various forms may take place during heating or under geothermal conditions. Biogenic silicas are readily converted into cristobalite under relatively mild temperature conditions (c. 800 °C), well below the temperature range of thermodynamic stability of cristobalite.;Dusts originated by quartz grinding have a peculiar reactivity arising from the homolytic and heterolytic rupture of the silicon-oxygen bonds, which leaves unsatisfied valencies as unpaired electrons (surface radicals) and surface charges. A similar, even more pronounced effect takes place with tridymite and cristobalite . The effect is less pronounced with coesite and does not occur with stishovite. If grinding is performed in dry air, oxygen or hydrogen peroxide aqueous solutions, reactive oxygen species (ROS)... are formed. Conversely, if grinding takes place in a wet atmosphere, silanols are formed rather than surface radicals;In aqueous suspensions, freshly ground surfaces generate ROS. Whether the ROS arise from the silica itself or from certain impurities exposed at the surface during the grinding procedure is still under debate; acid washing decreases the radical yield.

Particle Size

20 nm

Rotatable Bond Count

RTECS Number

VV7325000;VV7330000;VV7335000

UNII

ETJ7Z6XBU4

Vapor Pressure

0 mm Hg (approx) (NIOSH, 2016);approx 0 mm Hg;10 mm Hg @ 1732 °C;0 mmHg (approx)

MSDS

Download MSDS

COA