| content | ||||||||||||||||||||||||||||||||||||||||||
| Boron trioxide | |
|---|---|
 |
|
| Other names | boron oxide, diboron trioxide, boron sesquioxide, boric oxide, boria, anhydric boric acid |
| Identifiers | |
| CAS number | [1303-86-2] |
| Properties | |
| Molecular formula | B2O3 |
| Molar mass | 69.6182 g/mol |
| Appearance | clear, glassy solid |
| Density | 1.85 g/cm3, glass; 2.460 g/cm3, liquid; |
| Melting point |
480 °C |
| Boiling point |
1680 °C |
| Solubility in water | 2.2 g/100 g |
| Related compounds | |
| Related compounds | B2O2.5; B2O3·H2O (metaborite) |
| Supplementary data page | |
| Structure and properties |
n, εr, etc. |
| Thermodynamic data |
Phase behaviour Solid, liquid, gas |
| Spectral data | UV, IR, NMR, MS |
| 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 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-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. (1,2) The crystalline form (B2O3) is exclusively composed of BO3 triangles and is one-third 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 (3).
Contents |
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
See also
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 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.
- "Structural transformations in liquid, crystalline and glassy B2O3 under high pressure". Institute for High Pressure Physics RAS and Japan Atomic Energy Research Institute. (2003).
External links
- National Pollutant Inventory: Boron and compounds
- Australian Government information
- [1] US NIH hazard information
