Chemical compound
Barium borate is an inorganic compound, a borate of barium with a chemical convention BaB2O4 or Ba ( BO2 ) 2. It is available as a hydrate or dehydrated kind, as white gunpowder 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 ocular material. Barium borate was discovered and developed by Chen Chuangtian and others of the Fujian Institute of Research on the social organization of Matter, Chinese Academy of Sciences .

Properties.

crystal structure of BBO viewed about perpendicular to the c-axis. Colors : greens – Ba, pink – B, crimson – O

c axis BBO viewed along theaxis 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 frankincense does not have the same nonlinear properties as the β phase. [ 4 ] Alpha barium borate, α-BaB2O4 is an optical substantial with a identical wide optical transmission window from about 190 nm to 3500 nanometer. It has good mechanical properties and is a suitable material for high-octane ultraviolet polarization optics. [ 5 ] It can replace calcite, titanium dioxide or lithium niobate in Glan–Taylor prism, Glan–Thompson prism, walk-off glow splitters and early ocular components. It has low hygroscopicity, and its Mohs severity is 4.5. Its damage brink is 1 GW/cm2 at 1064 nanometer and 500 MW/cm2 at 355 nanometer. [ 1 ] Beta barium borate, β-BaB2O4, is a nonlinear optical material crystalline in the crop ~190–3300 nanometer. It can be used for spontaneous parametric down-conversion. Its Mohs hardness is besides 4.5. [ 1 ] [ 2 ] Gamma barium borate, γ-BaB2O4, discovered recently, was produced by heating beta barium borate 900 °C under 3 GPa of press. It was found to have a monoclinic quartz glass structure. [ 6 ] barium borate has firm negative uniaxial double refraction and can be phase-matched for type I ( ooe ) second-harmonic generation from 409.6 to 3500 nanometer. The temperature sensitivity of the indices of deflection is moo, leading to an unusually big ( 55 °C ) temperature phase-matching bandwidth. [ 2 ]

synthesis.

Barium borate can be prepared by reaction of an aqueous solution of boric acidic with barium hydroxide. The prepare γ-barium borate contains urine of crystallization that can not be wholly 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 arrant conversion to the β form. BBO train by this method acting does not contain trace amounts of BaB2O2 [ 7 ] BBO crystals for nonlinear optics can be grown from flow melt of barium borate, sodium oxide and sodium chloride. [ 8 ] 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 deposit temperatures. [ 9 ] Thin films of beta-barium borate can be prepared by sol-gel synthesis. [ 10 ]

Barium borate monohydrate is prepared from the solution of barium sulfide and sodium tetraborate. It is a white powderize. It is used as an linear to e.g. paints as fire retardant, model inhibitor, and corrosion inhibitor. It is besides 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 fire retardant for paints, textiles, and paper. [ 11 ]

Applications.

BBO is a popular nonlinear ocular crystal. Quantum linked photons are producible with beta barium borate. Barium borate is a antibacterial and antifungal. [ 12 ] It is added to paints, coatings, adhesives, plastics, and newspaper products. Barium borate is immune to ultraviolet radiation. It can act as UV stabilizer for polyvinyl chloride. [ 13 ] 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. normally available barium metaborate pigment comes in three grades ; Grade I is a barium metaborate itself, grade II is compounded with 27 % zinc oxide, and rate III is compounded with 18 % of zinc oxide and 29 % calcium sulfate. Barium borate shows synergistic performance with zinc borate. [ 14 ] Barium borate is used as a flow in some barium titanate and tip zirconate EIA Class 2 insulator ceramic formulations for ceramic capacitors, in come of about 2 %. The barium-boron proportion is critical for flux operation ; BaB2O2 message adversely affects the performance of the magnetic field. [ 7 ] [ 15 ] Barium borate- fly ash methamphetamine can be used as radiation shielding. such glasses are superior in performance to concrete and to other barium borate glasses. [ 16 ]

References.

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