Boron trioxide 2002950 206784805 2008-04-19T23:28:39Z Blanchardb 5311630 [[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 = }} | 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 &deg;C | BoilingPt = 1680 &deg;C | Solubility = 2.2 g/100 g }} | Section3 = {{Chembox Hazards | MainHazards = | FlashPt = | Autoignition = }} | 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]]