Boron Trioxide Information
Boron trioxide (or diboron trioxide) is one of the oxides of boron. It is a white, glassy solid with the formula B2O3. 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 (g-B2O3) is thought to be composed of boroxol rings which are six-membered rings composed of alternating 3-coordinate boron and 2-coordinate oxygen. This view is controversial, however, because no model has ever been made of glassy boron oxide of the correct density containing a large number of six-membered rings. The rings are thought to make a few BO3 triangles, but mostly link (polymerize) into ribbons and sheets.[3][4] The crystalline form (α-B2O3) see structure in the infobox[5]) is exclusively composed of BO3 triangles. This trigonal, quartz-like network undergoes a coesite-like transformation to monoclinic β-B2O3 at several gigapascals and is 9.5 GPa.[6]
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Preparation
Boron trioxide is produced by treating borax with sulfuric acid in a fusion furnace. At temperatures above 750 °C, the molten boron oxide layer separates out from sodium sulfate. It is then decanted, cooled and obtained in 96-97% purity.[2]
Hardness
The bulk modulus of β-B2O3 is rather high (K = 180 GPa). The Vickers hardness of g-B2O3 is 1.5 GPa and of β-B2O3 is 16 GPa.[7]
Applications
- Fluxing agent for glass and enamels
- Starting material for synthesizing other boron compounds such as boron carbide
- An additive used in glass fibres (optical fibres)
- It is used in the production of borosilicate glass
- The inert capping layer in the LEC process for the production of gallium arsenide single crystal
- As an acid catalyst in organic synthesis
See also
References
- ^ High temperature corrosion and materials chemistry: proceedings of the Per Kofstad Memorial Symposium. Proceedings of the Electrochemical Society. The Electrochemical Society. 2000. p. 496. ISBN 1566772613. http://books.google.com/?id=ZrxSWmueNMQC&pg=PA496.
- ^ a b Patnaik, Pradyot (2003). Handbook of Inorganic Chemical Compounds. McGraw-Hill. p. 119. ISBN 0070494398. http://books.google.com/?id=Xqj-TTzkvTEC&pg=PA119. Retrieved 2009-06-06.
- ^ Eckert, H. (1992). "Structural characterization of noncrystalline solids and glasses using solid state NMR". Prog. NMR Spectrosc. 24: 159. doi:10.1016/0079-6565(92)80001-V.
- ^ S.-J. Hwang, C. Femandez, J.P. Amoureux, J. Cho, S.W. Martin & M. Pruski. (1997). "Quantitative study of the short range order in B,O, and B,S, by MAS and two-dimensional triple-quantum MAS 11B NMR". Solid State Nuclear Magnetic Resonance 8 (2): 109–121. doi:10.1016/S0926-2040(96)01280-5. PMID 9203284.
- ^ G.E. Gurr, P.W. Montgomery, C.D. Knutson, B.T.Gorres (1970). "The Crystal Structure of Trigonal Diboron Trioxide". Acta Cryst. B 26: 906–915. doi:10.1107/S0567740870003369.
- ^ V. V. Brazhkin et al. (2003). "Structural transformations in liquid, crystalline and glassy B2O3 under high pressure". JETPh Lett. 78: 845. http://www.jetpletters.ac.ru/ps/47/article_679.ps.
- ^ V. A. Mukhanov, O. O. Kurakevich, and V. L. Solozhenko (2008). "On the Hardness of Boron (III) Oxide". Journal of Superhard Materials 30: 71. doi:10.3103/S1063457608010097.
External links
- National Pollutant Inventory: Boron and compounds
- Australian Government information
- US NIH hazard information. See NIH.
- Material Safety Data Sheet
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Categories: Boron compounds | Acidic oxides | Inorganic compounds | Glass compositions | Common oxide glass components | Sesquioxides
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