Barium borate

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Beta barium borate
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Barium borate
Barium Borate
Names
Other names
barium diborate, barium boron oxide, barium metaborate
Identifiers
3D model (
JSmol
)
ChemSpider
ECHA InfoCard
100.033.824 Edit this at Wikidata
EC Number
  • 237-222-4
UNII
  • InChI=1S/2BO2.Ba/c2*2-1-3;/q2*-1;+2 checkY
    Key: QBLDFAIABQKINO-UHFFFAOYSA-N checkY
  • InChI=1/2BO2.Ba/c2*2-1-3;/q2*-1;+2
    Key: QBLDFAIABQKINO-UHFFFAOYAX
  • [Ba+2].[O-]B=O.[O-]B=O
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
ne = 1.5534, no = 1.6776
Structure
Rhombohedral, hR126[3]
R3c, No. 161
a = 1.2529 nm, c = 1.274 nm
Hazards
GHS labelling:
GHS07: Exclamation mark
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).
☒N verify (what is checkY☒N ?)

Barium borate is an

nonlinear optical
material.

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

Crystal structure of BBO viewed nearly perpendicular to the c-axis. Colors: green – Ba, pink – B, red – O
BBO viewed along the c axis

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

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

Mohs hardness is also 4.5.[1][2]

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]

sol-gel synthesis.[11]

Barium borate monohydrate is prepared from the solution of

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.[12]

Applications

BBO is a popular nonlinear optical crystal.

Quantum linked photons are producible with beta barium borate. Barium borate is a bactericide and fungicide.[13]
It is added to paints, coatings, adhesives, plastics, and paper products.

Barium borate is resistant to

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.[15]

Barium borate is used as a

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.[8][16]

Barium borate-

radiation shielding. Such glasses are superior in performance to concrete and to other barium borate glasses.[17]

References

  1. ^ a b c Barium Borate (a-BBO) Crystal. casix.com
  2. ^ a b c BBO Crystals – Beta Barium Borate and Lithium Borate Archived February 12, 2012, at the Wayback Machine. clevelandcrystals.com
  3. .
  4. .
  5. ^ Alpha Barium Borate. Roditi.com. Retrieved on 2012-01-15.
  6. S2CID 246054700
    .
  7. .
  8. ^ a b Ross, Sidney D. "Barium borate preparation" U.S. patent 4,897,249 issued January 30, 1990
  9. ^ 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
  10. .
  11. .
  12. .
  13. . Retrieved 15 January 2012.
  14. ^ Koskiniemi, Mark S "Calcium pyroborate as a microbicide for plastics" U.S. patent 5,482,989 issued 01/09/1996
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  17. .