Boron trioxide
General
Other names	Boron oxide, Diboron trioxide, Boron sesquioxide, Boric oxide, Boria, Anhydric boric acid
Molecular formula	B2O3.
Molar mass	69.6182 g/mol
Appearance	Colorless, glassy solid.
CAS number	[[1303-86-2]]
EINECS number	2151258
Properties
Density and phase	1.85 g/cm3, glass; 2.460 g/cm3, liquid; 2.55 g/cm3, trigonal; 3.11–3.146 g/cm3, monoclinic
Solubility in water	2.2 g/100 g H2O
Solubility in alcohol	Soluble
Solubility in ether	N/A
Melting point	480°C (750 K)
Boiling point	1860°C (2133 K)
Acidity (pKa)	N/A
Structure
Molecular shape	N/A
Dipole moment	N/A
Hazards
MSDS	External MSDS
EU classification	N/A
R-phrases	N/A
S-phrases	N/A
PEL (US, OSHA)	N/A
IDLH (US, NIOSH)	N/A
Flash point	N/A
Autoignition temperature	N/A
Explosive limits in air	N/A
RTECS number	N/A
Supplementary data page
Structure & properties	n, εr, etc.
Thermodynamic data	Phase behaviour Solid, liquid, gas
Spectral data	UV, IR, NMR, MS
Related compounds
Other anions	None
Other cations	None
Related compounds	B2O2.5; B2O3·H2O (metaborite)
Except where noted otherwise, data are given for materials in their standard state (at 25°C, 100 kPa) Infobox disclaimer and references

Boron oxide is one of the oxides of boron. It is white, glassy, and solid, also known as diboron trioxide, formula B₂O₃. It is almost always found as the vitreose (amorphic) form; however, it can be crystallized after extensive annealing. It is one of the most difficult compounds known to crystallize. Glassy boron oxide (a-B₂O₃) 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 BO₃ triangles, but mostly link (polymerize) into ribbons and sheets. The crystalline form (B₂O₃) is exclusively composed of BO₃ triangles and is almost half as hard as quartz, 4 GPa Vickers. This trigonal, quartz-like network undergoes a monoclinic, coesite-like transformation of BO₄ tetrahedra at several gigapascals and is 9.5 GPa. Image File history File links Size of this preview: 631 × 599 pixelsFull resolution (1100 × 1045 pixel, file size: 309 KB, MIME type: image/png) File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... This article or section does not cite any references or sources. ... Molar mass is the mass of one mole of a chemical element or chemical compound. ... CAS registry numbers are unique numerical identifiers for chemical compounds, polymers, biological sequences, mixtures and alloys. ... The EINECS number (for European Inventory of Existing Chemical Substances) is a registry number given to each chemical substance commercially available in the European Union between 1 January 1971 and 18 September 1981. ... In physics, density is mass m per unit volume V. For the common case of a homogeneous substance, it is expressed as: where, in SI units: ρ (rho) is the density of the substance, measured in kg·m-3 m is the mass of the substance, measured in kg V is... In the physical sciences, a phase is a set of states of a macroscopic physical system that have relatively uniform chemical composition and physical properties (i. ... In crystallography, the rhombohedral (or trigonal) crystal system is one of the 7 lattice point groups. ... In crystallography, the monoclinic crystal system is one of the 7 lattice point groups. ... It has been suggested that this article or section be merged with Solution. ... This article describes water from a scientific and technical perspective. ... Grain alcohol redirects here. ... This article is about the chemical compound. ... The melting point of a crystalline solid is the temperature at which it changes state from solid to liquid. ... 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RTECS, also known as Registry of Toxic Effects of Chemical Substances, is a database of toxicity information compiled from the open scientific literature that is available for charge. ... This page provides supplementary chemical data on boron trioxide. ... This page provides supplementary chemical data on boron trioxide. ... The refractive index (or index of refraction) of a medium is a measure for how much the speed of light (or other waves such as sound waves) is reduced inside the medium. ... The relative dielectric constant of a material under given conditions is a measure of the extent to which it concentrates electrostatic lines of flux. ... This page provides supplementary chemical data on boron trioxide. ... This page provides supplementary chemical data on boron trioxide. ... Ultraviolet-Visible Spectroscopy or Ultraviolet-Visible Spectrophotometry (UV/ VIS) involves the spectroscopy of photons (spectrophotometry). ... Infrared spectroscopy (IR Spectroscopy) is the subset of spectroscopy that deals with the IR region of the EM spectrum. ... It has been suggested that NMR Data Processing be merged into this article or section. ... Mass spectrometry (also known as mass spectroscopy (deprecated)[1] or informally, mass-spec and MS) is an analytical technique used to measure the mass-to-charge ratio of ions. ... An electrostatic potential map of the nitrate ion (NO3−). Areas coloured red are lower in energy than areas colored yellow robert ford An ion is an atom or group of atoms which have lost or gained one or more electrons, making them negatively or positively charged. ... An electrostatic potential map of the nitrate ion (NO3−). Areas coloured red are lower in energy than areas colored yellow robert ford An ion is an atom or group of atoms which have lost or gained one or more electrons, making them negatively or positively charged. ... 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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

Glass can be made transparent and flat, or into other shapes and colors as shown in this sphere from the Verrerie of Brehat in Brittany. ... In a discussion of art technology, enamel (or vitreous enamel, or porcelain enamel in American English) is the colorful result of fusion of powdered glass to a substrate through the process of firing, usually between 750 and 850 degrees Celsius. ... General Name, Symbol, Number boron, B, 5 Chemical series metalloids Group, Period, Block 13, 2, p Appearance black/brown Standard atomic weight 10. ... Boron Carbide (chemical formula B4C) is an extremely hard ceramic material used in tank armor, bulletproof vests, and numerous industrial applications. ... Fiber Optic strands An optical fiber in American English or fibre in British English is a transparent thin fiber for transmitting light. ... It has been suggested that Kimax be merged into this article or section. ...

Hazard Information

• Australian Government information
• [1] US NIH hazard information

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Data

• The standard enthalpy of formation of boron oxide (s,a) at 25 °C: −302, −297.6 kcal/mol
• The standard free energy of formation of boron oxide (s,a) at 25 °C: −283, −280 kcal/mol

t In thermodynamics and molecular chemistry, the enthalpy or heat content (denoted as H or ΔH, or rarely as χ) is a quotient or description of thermodynamic potential of a system, which can be used to calculate the useful work obtainable from a closed thermodynamic system under constant pressure. ... The free energy is a measure of the amount of mechanical (or other) work that can be extracted from a system, and is helpful in engineering applications. ...

References

1. Eckert, H. Prog. NMR Spectrosc., 24 (1992) 159-293.
2. "Quantitative study of the short range order in B,O, and B,S, by MAS and two-dimensional triple-quantum MAS ¹¹B 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.
3. "Structural transformations in liquid, crystalline and glassy B₂O₃ under high pressure". Institute for High Pressure Physics RAS and Japan Atomic Energy Research Institute. (2003).

See also

• boron suboxide
• boric acid
• sassolite

Boron suboxide (chemical formula B6O) is a solid compound of boron and oxygen. ... Boric acid, also called boracic acid or orthoboric acid or Acidum Boricum, is a mild acid often used as an antiseptic, insecticide, flame retardant, in nuclear power plants to control the fission rate of uranium, and as a precursor of other chemical compounds. ... Sassolite is a borate mineral, and is the mineral form of boric acid. ...

External links

• National Pollutant Inventory: Boron and compounds

• Links to external chemical sources