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词条 Boron trioxide
释义

  1. Preparation

  2. Applications

  3. See also

  4. References

  5. External links

{{chembox
| Watchedfields = changed
| verifiedrevid = 443427049o
| ImageFile = B2O3powder.JPG
| ImageFile2 = Kristallstruktur Bortrioxid.png
| ImageName = Crystal structure of B2O3 [1]
| OtherNames = boron oxide, diboron trioxide, boron sesquioxide, boric oxide, boria

Boric acid anhydride


|Section1={{Chembox Identifiers
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 452485
| InChI = 1/B2O3/c3-1-5-2-4
| ChEBI_Ref = {{ebicite|correct|EBI}}
| ChEBI = 30163
| SMILES = O=BOB=O
| InChIKey = JKWMSGQKBLHBQQ-UHFFFAOYAI
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 1S/B2O3/c3-1-5-2-4
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = JKWMSGQKBLHBQQ-UHFFFAOYSA-N
| CASNo_Ref = {{cascite|correct|CAS}}
| CASNo = 1303-86-2
| PubChem = 518682
| RTECS = ED7900000
| EINECS = 215-125-8
}}
|Section2={{Chembox Properties
| Formula = B2O3
| MolarMass = 69.6182 g/mol
| Appearance = white, glassy solid
| Density = 2.460 g/cm3, liquid;

2.55 g/cm3, trigonal;

3.11–3.146 g/cm3, monoclinic


| MeltingPtC = 450
| MeltingPt_notes = (trigonal)
510 °C (tetrahedral)
| BoilingPtC = 1860
| BoilingPt_notes = ,[1] sublimes at 1500 °C[3]
| Solubility = 1.1 g/100mL (10 °C)
3.3 g/100mL (20 °C)
15.7 100 g/100mL (100 °C)
| SolubleOther = partially soluble in methanol
| pKa = ~ 4
| MagSus = -39.0·10−6 cm3/mol
}}
|Section4={{Chembox Thermochemistry
| DeltaHf = -1254 kJ/mol
| DeltaGf = -832 kJ/mol
| Entropy = 80.8 J/mol K
| HeatCapacity = 66.9 J/mol K
}}
|Section7={{Chembox Hazards
| EUClass = Repr. Cat. 2
| MainHazards = Irritant[4]
| NFPA-H = 2
| NFPA-F = 0
| NFPA-R = 0
| NFPA-S =
| FlashPt = noncombustible
| AutoignitionPt =
| LD50 = 3163 mg/kg (oral, mouse)[2]
| PEL = TWA 15 mg/m3[3]
| REL = TWA 10 mg/m3[3]
| IDLH = 2000 mg/m3[3]
}}
}}

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 (amorphous) form; however, it can be crystallized after extensive annealing (that is, under prolonged heat).

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. Because of the difficulty of building disordered models at the correct density with a large number of boroxol rings, this view was initially controversial, but such models have recently been constructed and exhibit properties in excellent agreement with experiment.[4] It is now recognized, from experimental and theoretical studies,[5][6][7][8][9] that the fraction of boron atoms belonging to boroxol rings in glassy B2O3 is somewhere between 0.73 and 0.83, with 0.75 ({{frac|3|4}}) corresponding to a 1:1 ratio between ring and non-ring units. The number of boroxol rings decays in the liquid state with increasing temperature.[10]

The crystalline form (α-B2O3) (see structure in the infobox[11]) is exclusively composed of BO3 triangles. This trigonal, quartz-like network undergoes a coesite-like transformation to monoclinic β-B2O3 at several gigapascals (9.5 GPa).[12]

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.[13]

Another method is heating boric acid above ~300 °C. Boric acid will initially decompose into steam, (H2O(g)) and metaboric acid (HBO2) at around 170 °C, and further heating above 300 °C will produce more steam and boron trioxide. The reactions are:

H3BO3 → HBO2 + H2O

2 HBO2 → B2O3 + H2O

Boric acid goes to anhydrous microcrystalline B2O3 in a heated fluidized bed.[14] Carefully controlled heating rate avoids gumming as water evolves. Molten boron oxide attacks silicates. Internally graphitized tubes via acetylene thermal decomposition are passivated.[15]

Crystallization of molten α-B2O3 at ambient pressure is strongly kinetically disfavored (compare liquid and crystal densities). Threshold conditions for crystallization of the amorphous solid are 10 kbar and ~200 °C.[16] Its proposed crystal structure in enantiomorphic space groups P31(#144); P32(#145)[17][18] (e.g., γ-glycine) has been revised to enantiomorphic space groups P3121(#152); P3221(#154)[19](e.g., α-quartz).

Boron oxide will also form when diborane (B2H6) reacts with oxygen in the air or trace amounts of moisture:

2B2H6(g) + 3O2(g) → 2B2O3(s) + 6H2(g)

B2H6(g) + 3H2O(g) → B2O3(s) + 6H2(g)[20]

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 Liquid Encapsulation Czochralski process for the production of gallium arsenide single crystal
  • As an acid catalyst in organic synthesis

See also

  • boron suboxide
  • boric acid
  • sassolite
  • Tris(2,2,2-trifluoroethyl) borate

References

1. ^{{cite book|url=https://books.google.com/books?id=ZrxSWmueNMQC&pg=PA496|page=496|title=High temperature corrosion and materials chemistry: proceedings of the Per Kofstad Memorial Symposium. Proceedings of the Electrochemical Society|publisher=The Electrochemical Society|year=2000|isbn=978-1-56677-261-7}}
2. ^{{IDLH|1303862|Boron oxide}}
3. ^1 2 3 {{PGCH|0060}}
4. ^{{cite journal |author1=Ferlat, G. |author2=Charpentier, T. |author3=Seitsonen, A. P. |author4=Takada, A. |author5=Lazzeri, M. |author6=Cormier, L. |author7=Calas, G. |author8=Mauri. F. | title = Boroxol Rings in Liquid and Vitreous B2O3 from First Principles | journal = Phys. Rev. Lett. | year = 2008 | volume = 101 |issue=6 | pages = 065504 | doi=10.1103/PhysRevLett.101.065504 |pmid=18764473 |bibcode=2008PhRvL.101f5504F }}; {{cite journal|last1=Ferlat|first1=G.|last2=Seitsonen|first2=A. P.|last3=Lazzeri|first3=M.|last4=Mauri|first4=F.|title=Hidden polymorphs drive vitrification in B2O3|journal=Nature Materials Letters|volume=11|issue=11|pages=925–929|date=2012|doi=10.1038/NMAT3416|pmid=22941329|arxiv=1209.3482|bibcode=2012NatMa..11..925F}}
5. ^{{cite journal|last1=Hung|first1=I.|display-authors=etal|title=Determination of the bond-angle distribution in vitreous B2O3 by rotation (DOR) NMR spectroscopy|journal=Journal of Solid State Chemistry|date=2009|volume=182|issue=9|pages=2402–2408|doi=10.1016/j.jssc.2009.06.025|bibcode=2009JSSCh.182.2402H}}
6. ^{{cite journal|last1=Soper|first1=A. K.|title=Boroxol rings from diffraction data on vitreous boron trioxide|journal=J. Phys.: Condens. Matter|date=2011|volume=23|issue=36|page=365402|doi=10.1088/0953-8984/23/36/365402|pmid=21865633|bibcode=2011JPCM...23.5402S}}
7. ^{{cite journal|last1=Joo|first1=C.|display-authors=etal|title=The ring structure of boron trioxide glass|journal=Journal of Non-Crystalline Solids|date=2000|volume=261|issue=1–3|pages=282–286|doi=10.1016/s0022-3093(99)00609-2|bibcode=2000JNCS..261..282J}}
8. ^{{cite journal|last1=Zwanziger|first1=J. W.|title=The NMR response of boroxol rings: a density functional theory study|journal=Solid State Nuclear Magnetic Resonance|date=2005|volume=27|issue=1–2|pages=5–9|doi=10.1016/j.ssnmr.2004.08.004|pmid=15589722}}
9. ^{{cite journal|last1=Micoulaut|first1=M.|title=The structure of vitreous B2O3 obtained from a thermostatistical model of agglomeration|journal=Journal of Molecular Liquids|date=1997|volume=71|issue=2–3|pages=107–114|doi=10.1016/s0167-7322(97)00003-2}}
10. ^{{cite journal |last1=Alderman, O. L. G. Ferlat, G. Baroni, A. Salanne, M. Micoulaut, M. Benmore, C. J. Lin, A. Tamalonis, A. Weber, J. K. R. |title=Liquid B2O3 up to 1700K: X-ray diffraction and boroxol ring dissolution |journal=Journal of Physics: Condensed Matter |date=2015 |volume=27 |issue=45 |page=455104 |doi=10.1088/0953-8984/27/45/455104 |pmid=26499978 }}
11. ^1 {{cite journal |author1=Gurr, G. E. |author2=Montgomery, P. W. |author3=Knutson, C. D. |author4=Gorres, B. T. | title = The Crystal Structure of Trigonal Diboron Trioxide | journal = Acta Crystallographica B | year = 1970 | volume = 26 | issue = 7 | pages = 906–915 | doi = 10.1107/S0567740870003369 }}
12. ^{{cite journal |author1=Brazhkin, V. V. |author2=Katayama, Y. |author3=Inamura, Y. |author4=Kondrin, M. V. |author5=Lyapin, A. G. |author6=Popova, S. V. |author7=Voloshin, R. N. | title = Structural transformations in liquid, crystalline and glassy B2O3 under high pressure | journal = JETP Letters | year = 2003 | volume = 78 | issue = 6 | pages = 393–397 | doi = 10.1134/1.1630134 | url = http://www.jetpletters.ac.ru/ps/47/article_679.shtml |bibcode=2003JETPL..78..393B }}
13. ^1 {{cite book | last = Patnaik | first = P. | year = 2003 | title = Handbook of Inorganic Chemical Compounds | publisher = McGraw-Hill | page = 119 | isbn =978-0-07-049439-8 | url = https://books.google.com/books?id=Xqj-TTzkvTEC&pg=PA119 | accessdate = 2009-06-06 }}
14. ^{{cite journal | title = Production of anhydrous, crystalline boron oxide in fluidized bed reactor |author1=Kocakuşak, S. |author2=Akçay, K. |author3=Ayok, T. |author4=Koöroğlu, H. J. |author5=Koral, M. |author6=Savaşçi, Ö. T. |author7=Tolun, R. | journal = Chemical Engineering and Processing | year = 1996 | volume = 35 | issue = 4 | pages = 311–317 | doi = 10.1016/0255-2701(95)04142-7 }}
15. ^{{cite journal | author = Morelock, C. R. | title = Research Laboratory Report #61-RL-2672M | year = 1961 | publisher = General Electric }}
16. ^{{cite journal |author1=Aziz, M. J. |author2=Nygren, E. |author3=Hays, J. F. |author4=Turnbull, D. | title = Crystal Growth Kinetics of Boron Oxide Under Pressure | journal = Journal of Applied Physics | year = 1985 | volume = 57 | issue = 6 | page = 2233 | doi = 10.1063/1.334368 | url = http://dash.harvard.edu/handle/1/3645198 |bibcode=1985JAP....57.2233A }}
17. ^{{cite journal | title = The crystal structure of trigonal diboron trioxide | last1 = Gurr | first1 = G. E. | last2 = Montgomery | first2 = P. W. | last3 = Knutson | first3 = C. D. | last4 = Gorres | first4 = B. T. | journal = Acta Crystallographica B | year = 1970 | volume = 26 | issue = 7 | pages = 906–915 | doi = 10.1107/S0567740870003369 }}
18. ^{{cite journal | last1 = Strong | first1 = S. L. | last2 = Wells | first2 = A. F. | last3 = Kaplow | first3 = R. | title = On the crystal structure of B2O3 | journal = Acta Crystallographica B | year = 1971 | volume = 27 | issue = 8 | pages = 1662–1663 | doi = 10.1107/S0567740871004515 }}
19. ^{{cite journal | last1 = Effenberger | first1 = H. | last2 = Lengauer | first2 = C. L. | last3 = Parthé | first3 = E. | title = Trigonal B2O3 with Higher Space-Group Symmetry: Results of a Reevaluation | journal = Monatshefte für Chemie | year = 2001 | volume = 132 | issue = 12 | pages = 1515–1517 | doi = 10.1007/s007060170008 }}
20. ^{{cite journal | author = AirProducts | title = Diborane Storage & Delivery | year = 2011 | url = http://www.airproducts.com/~/media/downloads/other/D/en-diborane-electronics-technical-bulletin.pdf}}

External links

  • [https://web.archive.org/web/20060209040519/http://www.npi.gov.au/database/substance-info/profiles/15.html National Pollutant Inventory: Boron and compounds]
  • [https://web.archive.org/web/20050717211845/http://www.nohsc.gov.au/OHSInformation/Databases/ExposureStandards/az/Boron_oxide.htm Australian Government information]
  • US NIH hazard information. See NIH.
  • Material Safety Data Sheet
  • [https://www.cdc.gov/niosh/npg/npgd0060.html CDC - NIOSH Pocket Guide to Chemical Hazards - Boron oxide]
{{Boron compounds}}{{Oxides}}{{Authority control}}{{oxygen compounds}}{{DEFAULTSORT:Boron Trioxide}}

4 : Boron compounds|Acidic oxides|Glass compositions|Sesquioxides
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