Boron trioxide
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206784805
2008-04-19T23:28:39Z
Blanchardb
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[[WP:UNDO|Undid]] revision 206783566 by [[Special:Contributions/Passwordisqwerty02|Passwordisqwerty02]] ([[User talk:Passwordisqwerty02|talk]])
{{Chembox new
| ImageFile = Boron-trioxide-3D-balls.png
| ImageSize =
| IUPACName =
| OtherNames = [[boron oxide]], [[diboron trioxide]], [[boron sesquioxide]], [[boric oxide]], [[boria]], [[anhydric boric acid]]
| Section1 = {{Chembox Identifiers
| CASNo = 1303-86-2
| PubChem =
| SMILES =
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| Section2 = {{Chembox Properties
| Formula = B<sub>2</sub>O<sub>3</sub>
| MolarMass = 69.6182 g/mol
| Appearance = clear, glassy solid
| Density = 1.85 g/cm<sup>3</sup>, glass;<br/>
2.460 g/cm<sup>3</sup>, liquid;<br/>
2.55 g/cm<sup>3</sup>, trigonal;<br/>
3.11–3.146 g/cm<sup>3</sup>, monoclinic
| MeltingPt = 480 °C
| BoilingPt = 1680 °C
| Solubility = 2.2 g/100 g
}}
| Section3 = {{Chembox Hazards
| MainHazards =
| FlashPt =
| Autoignition =
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| Section4 = {{Chembox Related
| OtherCpds = B<sub>2</sub>O<sub>2.5</sub>;<br>B<sub>2</sub>O<sub>3</sub>·H<sub>2</sub>O (metaborite)
}}
}}
'''Boron oxide''' is one of the oxides of [[boron]]. It is white, glassy, and solid, also known as '''diboron trioxide''', formula B<sub>2</sub>O<sub>3</sub>. It is almost always found as the vitreous (amorphic) form; however, it can be crystallized after extensive [[annealing]]. It is one of the most difficult compounds known to crystallize.
Glassy boron oxide (α-B<sub>2</sub>O<sub>3</sub>) is thought to be composed of boroxol rings which are six-membered rings composed of alternating 3-coordinate boron and 2-coordinate oxygen. The rings make a few BO<sub>3</sub> triangles, but mostly link (polymerize) into ribbons and sheets. (1,2) The crystalline form (B<sub>2</sub>O<sub>3</sub>) is exclusively composed of BO<sub>3</sub> triangles and is one-third as hard as quartz, 4 [[gigapascal|GPa]] [[Vickers hardness|Vickers]]. This trigonal, [[trapezohedron|quartz-like]] network undergoes a monoclinic, [[coesite]]-like transformation of BO<sub>4</sub> tetrahedra at several gigapascals and is 9.5 GPa (3).
==Applications==
*Fluxing agent for [[glass]] and [[vitreous enamel|enamels]]
*Starting material for synthesizing other [[boron]] compounds such as [[boron carbide]]
*An additive used in glass fibres ([[optical fibre]]s)
*It is used in the production of [[borosilicate glass]]
==See also==
*[[boron suboxide]]
*[[boric acid]]
*[[sassolite]]
== References ==
#Eckert, H. Prog. ''NMR Spectrosc.'', 24 (1992) 159-293.
#"Quantitative study of the short range order in B,O, and B,S, by MAS and two-dimensional triple-quantum MAS <sup>11</sup>B NMR". S.-J. Hwang, C. Femandez, J.P. Amoureux, J. Cho, S.W. Martin & M. Pruski. ''Solid State Nuclear Magnetic Resonance'' 8 (1997) 109-121.
#"[http://www.jetpletters.ac.ru/ps/47/article_679.ps Structural transformations in liquid, crystalline and glassy B<sub>2</sub>O<sub>3</sub> under high pressure]". Institute for High Pressure Physics RAS and Japan Atomic Energy Research Institute. (2003).
==External links==
*[http://www.npi.gov.au/database/substance-info/profiles/15.html National Pollutant Inventory: Boron and compounds]
*[http://www.nohsc.gov.au/OHSInformation/Databases/ExposureStandards/az/Boron_oxide.htm Australian Government information]
*[http://toxnet.nlm.nih.gov/cgi-bin/sis/search/r?dbs+hsdb:@term+@rn+@rel+1303-86-2] US [[NIH]] hazard information
[[Category:Boron compounds]]
[[Category:Oxides]]
[[Category:Acidic oxides]]
[[Category:Inorganic compounds]]
[[Category:Glass types]]
[[cs:Oxid boritý]]
[[de:Bortrioxid]]
[[es:Óxido de boro]]
[[it:Anidride borica]]
[[vi:Ôxít bo]]