Barium borate
Names | |
---|---|
Other names
barium diborate, barium boron oxide, barium metaborate
| |
Identifiers | |
| |
3D model (
JSmol ) |
|
ChemSpider | |
ECHA InfoCard
|
100.033.824 |
EC Number |
|
PubChem CID
|
|
UNII | |
CompTox Dashboard (EPA)
|
|
| |
| |
Properties | |
BaB2O4 or Ba(BO2)2 | |
Molar mass | 222.95 |
Appearance | white powder or colorless crystals |
Odor | odorless |
Density | 3.85 g/cm3[1] |
Melting point | 1,095 °C (2,003 °F; 1,368 K)[2] |
Solubility in hydrochloric acid | soluble |
Refractive index (nD)
|
ne = 1.5534, no = 1.6776 |
Structure | |
Rhombohedral, hR126[3] | |
R3c, No. 161 | |
a = 1.2529 nm, c = 1.274 nm
| |
Hazards | |
GHS labelling: | |
Warning | |
H302 | |
P264, P270, P301+P312, P330, P501 | |
Flash point | Non-flammable |
Safety data sheet (SDS) | MSDS |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|
Barium borate is an
Barium borate was discovered and developed by Chen Chuangtian and others of the Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences.
Properties
Barium borate exists in three major crystalline forms: alpha, beta, and gamma. The low-temperature beta phase converts into the alpha phase upon heating to 925 °C. β-Barium borate (BBO) differs from the α form by the positions of the barium ions within the crystal. Both phases are birefringent, however the α phase possesses centric symmetry and thus does not have the same nonlinear properties as the β phase.[4]
Alpha barium borate, α-BaB2O4 is an optical material with a very wide optical transmission window from about 190 nm to 3500 nm. It has good mechanical properties and is a suitable material for high-power
Beta barium borate, β-BaB2O4, is a
Gamma barium borate, γ-BaB2O4, discovered recently, was produced by heating beta barium borate 900 °C under 3 GPa of pressure. It was found to have a monoclinic crystal structure.[6]
Barium borate has strong negative uniaxial birefringence and can be phase-matched for type I (ooe) second-harmonic generation from 409.6 to 3500 nm. The temperature sensitivity of the indices of refraction is low, leading to an unusually large (55 °C) temperature phase-matching bandwidth.[2]
Although the ambient-pressure α and β crystal phases contain only trigonal, sp2 hybridized, boron, BBO glass has around 40% of the boron on tetrahedral, sp3 hybridized, sites. In the liquid state the relative fractions of sp2 and sp3 boron are temperature-dependent, with the trigonal planar coordination favored at higher temperatures.[7]
Synthesis
Barium borate can be prepared by reaction of an aqueous solution of boric acid with barium hydroxide. The prepared γ-barium borate contains water of crystallization that can not be completely removed by drying at 120 °C. Dehydrated γ-barium borate can be prepared by heating to 300–400 °C. Calcination at about 600–800 °C causes complete conversion to the β form. BBO prepared by this method does not contain trace amounts of BaB2O2[8]
BBO crystals for nonlinear optics can be grown from fluxed melt of barium borate, sodium oxide and sodium chloride.[9]
Barium borate monohydrate is prepared from the solution of
Barium borate dihydrate is prepared from the solution of sodium metaborate and barium chloride at 90–95 °C. After cooling to room temperature, white powder is precipitated. Barium borate dihydrate loses water at above 140 °C. It is used as a flame retardant for paints, textiles, and paper.[12]
Applications
BBO is a popular nonlinear optical crystal.
Barium borate is resistant to
The solubility of barium borate is a disadvantage when used as a pigment.
Barium borate is used as a
Barium borate-
References
- ^ a b c Barium Borate (a-BBO) Crystal. casix.com
- ^ a b c BBO Crystals – Beta Barium Borate and Lithium Borate Archived February 12, 2012, at the Wayback Machine. clevelandcrystals.com
- .
- S2CID 101903774.
- ^ Alpha Barium Borate. Roditi.com. Retrieved on 2012-01-15.
- S2CID 246054700.
- PMID 37290074.
- ^ a b Ross, Sidney D. "Barium borate preparation" U.S. patent 4,897,249 issued January 30, 1990
- ^ Gualtieri, Devlin M.; Chai, Bruce H. T. "High temperature solution growth of barium borate (BaB2O4)" U.S. patent 4,931,133 issued June 5, 1990
- .
- .
- ISBN 978-0-8493-8671-8.
- ISBN 978-0-471-95461-3. Retrieved 15 January 2012.
- ^ Koskiniemi, Mark S "Calcium pyroborate as a microbicide for plastics" U.S. patent 5,482,989 issued 01/09/1996
- ISBN 978-0-8031-2060-0.
- S2CID 97981458.
- .