Barium borate is an inorganic compound, a borate of barium with a chemical formula BaB2O4 or Ba(BO2)2. It is available as a hydrate or dehydrated form, as white powder or colorless crystals. The crystals exist in the high-temperature α phase and low-temperature β phase, abbreviated as BBO; both phases are birefringent, and BBO is a common nonlinear optical material.
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| Names | |
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| Other names
barium diborate, barium boron oxide, barium metaborate
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| Identifiers | |
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3D model (JSmol)
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| ChemSpider | |
| ECHA InfoCard | 100.033.824 |
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PubChem CID
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| UNII | |
CompTox Dashboard (EPA)
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| 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)
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ne = 1.5534, no = 1.6776 |
| Structure | |
| Rhombohedral, hR126[3] | |
| R3c, No. 161 | |
a = 1.2529 nm, c = 1.274 nm
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| Hazards | |
| GHS labelling: | |
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| 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).
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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
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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 ultraviolet polarization optics.[5] It can replace calcite, titanium dioxide or lithium niobate in Glan–Taylor prisms, Glan–Thompson prisms, walk-off beam splitters and other optical components. It has low hygroscopicity, and its Mohs hardness is 4.5. Its damage threshold is 1 GW/cm2 at 1064 nm and 500 MW/cm2 at 355 nm.[1]
Beta barium borate, β-BaB2O4, is a nonlinear optical material transparent in the range ~190–3300 nm. It can be used for spontaneous parametric down-conversion. Its Mohs hardness is also 4.5.[1][2] The material exhibits a melting temperature of 1268 K,[6] with anisotropic thermal expansion coefficients: and α₃₃ = 36 × 10⁻⁶ K⁻¹.[7]
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.[8]
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.[9]
Synthesis
editBarium 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[10]
BBO crystals for nonlinear optics can be grown from fluxed melt of barium borate, sodium oxide and sodium chloride.[11]
Thin films of barium borate can be prepared by MOCVD from barium(II) hydro-tri(1-pyrazolyl)borate. Different phases can be obtained depending on deposition temperatures.[12] Thin films of beta-barium borate can be prepared by sol-gel synthesis.[13]
Barium borate monohydrate is prepared from the solution of barium sulfide and sodium tetraborate. It is a white powder. It is used as an additive to e.g. paints as flame retardant, mold inhibitor, and corrosion inhibitor. It is also used as a white pigment.
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.[14]
Applications
editBBO is a popular nonlinear optical crystal. Quantum linked photons are producible with beta barium borate. Barium borate is a bactericide and fungicide.[15] It is added to paints, coatings, adhesives, plastics, and paper products.
Barium borate is resistant to ultraviolet radiation. It can act as UV stabilizer for polyvinyl chloride.[16]
The solubility of barium borate is a disadvantage when used as a pigment. Silica-coated powders are available. The alkaline properties and the anodic passivation properties of the borate ion enhance the anticorrosion performance. Commonly available barium metaborate pigment comes in three grades; Grade I is a barium metaborate itself, grade II is compounded with 27% zinc oxide, and grade III is compounded with 18% of zinc oxide and 29% calcium sulfate. Barium borate shows synergistic performance with zinc borate.[17]
Barium borate is used as a flux in some barium titanate and lead zirconate EIA Class 2 dielectric ceramic formulations for ceramic capacitors, in amount of about 2%. The barium-boron ratio is critical for flux performance; BaB2O2 content adversely affects the performance of the flux.[10][18]
Barium borate-fly ash glass can be used as radiation shielding. Such glasses are superior in performance to concrete and to other barium borate glasses.[19]
References
edit- ^ 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
- ^ Guiqin, Dai; Wei, Lin; An, Zheng; Qingzhen, Huang; Jingkui, Liang (1990). "Thermal Expansion of the Low-Temperature Form of BaB2O4". Journal of the American Ceramic Society. 73 (8): 2526–2527. doi:10.1111/j.1151-2916.1990.tb07626.x.
- ^ Nikogosyan, D. N. (1991). "Beta barium borate (BBO)". Applied Physics A. 52 (6): 359–368. Bibcode:1991ApPhA..52..359N. doi:10.1007/BF00323647. S2CID 101903774.
- ^ Alpha Barium Borate. Roditi.com. Retrieved on 2012-01-15.
- ^ Nikogosyan, David (2005). "Chapter 2: Basic Nonlinear Optical Crystals". Nonlinear Optical Crystals: A Complete Survey (1st ed.). Springer New York, NY. p. 6. ISBN 9780387220222.
- ^ Trento, Chin (Oct 18, 2024). "From Structure to Application: Is BIBO or BBO the Better Crystal?". Stanford Advanced Materials. Retrieved Nov 8, 2024.
- ^ Bekker, Tatyana B.; Podborodnikov, Ivan V.; Sagatov, Nursultan E.; Shatskiy, Anton; Rashchenko, Sergey; Sagatova, Dinara N.; Davydov, Alexey; Litasov, Konstantin D. (2022). "γ-BaB2O4: High-Pressure High-Temperature Polymorph of Barium Borate with Edge-Sharing BO4 Tetrahedra". Inorganic Chemistry. 61 (4). ACS Publications: 2340–2350. doi:10.1021/acs.inorgchem.1c03760. PMID 35040639. S2CID 246054700.
- ^ Alderman, Oliver; Benmore, Chris; Holland, Diane; Weber, Rick (2023). "Boron coordination change in barium borate melts and glasses and its contribution to configurational heat capacity, entropy, and fragility". Journal of Chemical Physics. 158 (22): 224501. Bibcode:2023JChPh.158v4501A. doi:10.1063/5.0153282. PMID 37290074.
- ^ a b US 4897249, Ross, Sidney D., "Barium borate preparation", issued Jan 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
- ^ Malandrino, G.; Lo Nigro, R.; Fragalà, I. L. (2007). "An MOCVD Route to Barium Borate Thin Films from a Barium Hydro-tri(1-pyrazolyl)borate Single-Source Precursor". Chemical Vapor Deposition. 13 (11): 651. doi:10.1002/cvde.200706611.
- ^ C. Lu; S. S. Dimov & R. H. Lipson (2007). "Poly(vinyl pyrrolidone)-Assisted Sol−Gel Deposition of Quality β-Barium Borate Thin Films for Photonics Applications". Chem. Mater. 19 (20): 5018. doi:10.1021/cm071037m.
- ^ Perry, Dale L.; Phillips, Sidney L., eds. (1995). Handbook of inorganic compounds. Boca Raton: CRC Press. p. 3. ISBN 978-0-8493-8671-8.
- ^ Henry Warson; C. A. Finch (2001). Applications of Synthetic Resin Latices: Latices in surface castings : emulsion paints. John Wiley and Sons. pp. 885–. 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
- ^ J. V. Koleske (1995). Paint and coating testing manual: fourteenth edition of the Gardner-Sward handbook. Vol. 17. ASTM International. ISBN 978-0-8031-2060-0.
- ^ K. Singh; Indurkar, Aruna (1988). "Dielectrics of lead zirconate bonded with barium borate glass" (PDF). Bull. Mater. Sci. 11: 55. doi:10.1007/BF02744501. S2CID 97981458.
- ^ Singh, Sukhpal; Kumar, Ashok; Singh, Devinder; Thind, Kulwant Singh; Mudahar, Gurmel S. (2008). "Barium-borate-flyash glasses : As radiation shielding materials". Nuclear Instruments and Methods in Physics Research Section B. 266 (1): 140. Bibcode:2008NIMPB.266..140S. doi:10.1016/j.nimb.2007.10.018.