Barium borate
Encyclopedia
Barium borate, also called barium diborate, barium boron oxide, barium metaborate, or (as an optical crystal) BBO (BaB2O4 or Ba(BO2)2) is an inorganic compound
, a borate
of barium
. It is available as a hydrate
or dehydrated.
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.
Barium borate is a biocide
registered in USA since 1960 as a broad-spectrum bactericide and fungicide
. It is added to paints, coatings, adhesives, plastics, and paper and paper products.
Barium borate is resistant to moisture and ultraviolet
radiation. It can act as UV stabilizer
for polyvinyl chloride
.
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
.
Alpha barium borate, α-BaB2O4, the high-temperature phase, is an optical material with high birefringence
and very wide optical transmission window from about 189 nm to 3500 nm. It has good mechanical properties and is a suitable material for high-power ultraviolet
polarization optics
. It can replace calcite
, titanium dioxide
, lithium niobate
, etc. in Glan-Taylor prism
s, Glan-Thompson prism
s, walk-off beam splitter
s, etc. It is low-hygroscopic, its Mohs hardness is 4.5. Its damage threshold is 1 GW/cm2 at 1064 nm and 500 MW/cm2 at 355 nm. Its density is 3.85 g/cm3.
Beta barium borate
, β-BaB2O4, is a nonlinear optical material
.
Thin film
s of BBO can be prepared by MOCVD
from barium(II) hydro-tri(1-pyrazolyl)borate. Different phases can be obtained depending on deposition temperatures. Thin films of beta-barium borate can be prepared by sol-gel synthesis.
Alpha (and to less degree beta) barium borate crystals can be used as neutron detectors.
Barium borate can be prepared by reaction of an aqueous solution
of boric acid
with barium hydroxide
. The prepared γ-BBO contains water of crystallization
that can not be completely removed by drying at 120 °C. Dehydrated γ-BBO can be prepared by heating to 300-400 °C. Calcination
at about 600-800 °C causes complete conversion to β-BBO. BBO prepared by this method does not contain trace amounts of BaB2O2
Barium borate is used as a flux
in some barium titanate
and lead zirconate EIA Class 2 dielectric
ceramic
formulations for ceramic capacitor
s, in amount of about 2%. The barium-boron ratio is critical for flux performance; BaB2O2 content adversely affects the performance of the flux.
Beta barium borate
crystals for nonlinear optics can be grown from fluxed melt of BBO, sodium oxide
and sodium chloride
.
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.
Inorganic compound
Inorganic compounds have traditionally been considered to be of inanimate, non-biological origin. In contrast, organic compounds have an explicit biological origin. However, over the past century, the classification of inorganic vs organic compounds has become less important to scientists,...
, a borate
Borate
Borates are chemical compounds which contain oxoanions of boron in oxidation state +3. The simplest borate ion, BO33−, has a trigonal planar structure. Other borates are made up of trigonal BO3 or tetrahedral BO4 structural units, sharing oxygen atoms...
of barium
Barium
Barium is a chemical element with the symbol Ba and atomic number 56. It is the fifth element in Group 2, a soft silvery metallic alkaline earth metal. Barium is never found in nature in its pure form due to its reactivity with air. Its oxide is historically known as baryta but it reacts with...
. It is available as a hydrate
Hydrate
Hydrate is a term used in inorganic chemistry and organic chemistry to indicate that a substance contains water. The chemical state of the water varies widely between hydrates, some of which were so labeled before their chemical structure was understood....
or dehydrated.
Barium borate monohydrate is prepared from the solution of barium sulfide
Barium sulfide
Barium sulfide is the inorganic compound with the formula BaS. BaS is an important precursor to other barium compounds including BaCO3 and the pigment lithopone, ZnS/BaSO4. Like other chalcogenides of the alkaline earth metals, BaS is a short wavelength emitters for electronic displays...
and sodium tetraborate. It is a white powder. It is used as an additive to e.g. paints as flame retardant
Flame retardant
Flame retardants are chemicals used in thermoplastics, thermosets, textiles and coatings that inhibit or resist the spread of fire. These can be separated into several different classes of chemicals:...
, mold inhibitor, and corrosion inhibitor
Corrosion inhibitor
A corrosion inhibitor is a chemical compound that, when added to a liquid or gas, decreases the corrosion rate of a material, typically a metal or an alloy. The effectiveness of a corrosion inhibitor depends on fluid composition, quantity of water, and flow regime...
. It is also used as a white pigment
Pigment
A pigment is a material that changes the color of reflected or transmitted light as the result of wavelength-selective absorption. This physical process differs from fluorescence, phosphorescence, and other forms of luminescence, in which a material emits light.Many materials selectively absorb...
.
Barium borate dihydrate is prepared from the solution of sodium metaborate and barium chloride
Barium chloride
Barium chloride is the inorganic compound with the formula BaCl2. It is one of the most common water-soluble salts of barium. Like other barium salts, it is toxic and imparts a yellow-green coloration to a flame. It is also hygroscopic....
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
Flame retardant
Flame retardants are chemicals used in thermoplastics, thermosets, textiles and coatings that inhibit or resist the spread of fire. These can be separated into several different classes of chemicals:...
for paints, textiles, and paper.
Barium borate is a biocide
Biocide
A biocide is a chemical substance or microorganism which can deter, render harmless, or exert a controlling effect on any harmful organism by chemical or biological means. Biocides are commonly used in medicine, agriculture, forestry, and industry...
registered in USA since 1960 as a broad-spectrum bactericide and fungicide
Fungicide
Fungicides are chemical compounds or biological organisms used to kill or inhibit fungi or fungal spores. Fungi can cause serious damage in agriculture, resulting in critical losses of yield, quality and profit. Fungicides are used both in agriculture and to fight fungal infections in animals...
. It is added to paints, coatings, adhesives, plastics, and paper and paper products.
Barium borate is resistant to moisture and ultraviolet
Ultraviolet
Ultraviolet light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays, in the range 10 nm to 400 nm, and energies from 3 eV to 124 eV...
radiation. It can act as UV stabilizer
UV Stabilizers in plastics
UV light stabilizers are used frequently in plastics, including cosmetics and films. The primary function is to protect the substance from the long-term degradation effects from light, most frequently ultraviolet light...
for polyvinyl chloride
Polyvinyl chloride
Polyvinyl chloride, commonly abbreviated PVC, is a thermoplastic polymer. It is a vinyl polymer constructed of repeating vinyl groups having one hydrogen replaced by chloride. Polyvinyl chloride is the third most widely produced plastic, after polyethylene and polypropylene. PVC is widely used in...
.
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
Passivation
Passivation is the process of making a material "passive", and thus less reactive with surrounding air, water, or other gases or liquids. The goal is to inhibit corrosion, whether for structural or cosmetic reasons. Passivation of metals is usually achieved by the deposition of a layer of oxide...
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
Zinc oxide
Zinc oxide is an inorganic compound with the formula ZnO. It is a white powder that is insoluble in water. The powder is widely used as an additive into numerous materials and products including plastics, ceramics, glass, cement, rubber , lubricants, paints, ointments, adhesives, sealants,...
, and grade III is compounded with 18% of zinc oxide
Zinc oxide
Zinc oxide is an inorganic compound with the formula ZnO. It is a white powder that is insoluble in water. The powder is widely used as an additive into numerous materials and products including plastics, ceramics, glass, cement, rubber , lubricants, paints, ointments, adhesives, sealants,...
and 29% calcium sulfate
Calcium sulfate
Calcium sulfate is a common laboratory and industrial chemical. In the form of γ-anhydrite , it is used as a desiccant. It is also used as a coagulant in products like tofu. In the natural state, unrefined calcium sulfate is a translucent, crystalline white rock...
. Barium borate shows synergistic performance with zinc borate
Zinc borate
Zinc borate is an inorganic compound, a borate of zinc. It is a white crystalline or amorphous powder insoluble in water. Its toxicity is low. Its melting point is 980 °C....
.
Alpha barium borate, α-BaB2O4, the high-temperature phase, is an optical material with high birefringence
Birefringence
Birefringence, or double refraction, is the decomposition of a ray of light into two rays when it passes through certain anisotropic materials, such as crystals of calcite or boron nitride. The effect was first described by the Danish scientist Rasmus Bartholin in 1669, who saw it in calcite...
and very wide optical transmission window from about 189 nm to 3500 nm. It has good mechanical properties and is a suitable material for high-power ultraviolet
Ultraviolet
Ultraviolet light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays, in the range 10 nm to 400 nm, and energies from 3 eV to 124 eV...
polarization optics
Optics
Optics is the branch of physics which involves the behavior and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behavior of visible, ultraviolet, and infrared light...
. It can replace calcite
Calcite
Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate . The other polymorphs are the minerals aragonite and vaterite. Aragonite will change to calcite at 380-470°C, and vaterite is even less stable.-Properties:...
, titanium dioxide
Titanium dioxide
Titanium dioxide, also known as titanium oxide or titania, is the naturally occurring oxide of titanium, chemical formula . When used as a pigment, it is called titanium white, Pigment White 6, or CI 77891. Generally it comes in two different forms, rutile and anatase. It has a wide range of...
, lithium niobate
Lithium niobate
Lithium niobate is a compound of niobium, lithium, and oxygen. Its single crystals are an important material for optical waveguides, mobile phones, optical modulators and various other linear and non-linear optical applications.-Properties:...
, etc. in Glan-Taylor prism
Glan-Taylor prism
A Glan–Taylor prism is a type of prism which is used as a polarizer or polarizing beam splitter. It is one of the most common types of modern polarizing prism. It was first described by Archard and Taylor in 1948....
s, Glan-Thompson prism
Glan-Thompson prism
A Glan–Thompson prism is a type of polarizing prism similar to the Nicol and Glan–Foucault prisms. It consists of two right-angled calcite prisms that are cemented together by their long faces. The optical axes of the calcite crystals are parallel and aligned perpendicular to the plane of reflection...
s, walk-off beam splitter
Beam splitter
A beam splitter is an optical device that splits a beam of light in two. It is the crucial part of most interferometers.In its most common form, a rectangle, it is made from two triangular glass prisms which are glued together at their base using Canada balsam...
s, etc. It is low-hygroscopic, its Mohs hardness is 4.5. Its damage threshold is 1 GW/cm2 at 1064 nm and 500 MW/cm2 at 355 nm. Its density is 3.85 g/cm3.
Beta barium borate
Beta Barium Borate
Beta barium borate is a crystal frequently used for frequency mixing and other nonlinear optics applications...
, β-BaB2O4, is a nonlinear optical material
Nonlinear optics
Nonlinear optics is the branch of optics that describes the behavior of light in nonlinear media, that is, media in which the dielectric polarization P responds nonlinearly to the electric field E of the light...
.
Thin film
Thin film
A thin film is a layer of material ranging from fractions of a nanometer to several micrometers in thickness. Electronic semiconductor devices and optical coatings are the main applications benefiting from thin film construction....
s of BBO can be prepared by MOCVD
Metalorganic vapour phase epitaxy
Metalorganic vapour phase epitaxy , also known as organometallic vapour phase epitaxy or metalorganic chemical vapour deposition , is a chemical vapour deposition method of epitaxial growth of materials, especially compound semiconductors, from the surface reaction of organic compounds or...
from barium(II) hydro-tri(1-pyrazolyl)borate. Different phases can be obtained depending on deposition temperatures. Thin films of beta-barium borate can be prepared by sol-gel synthesis.
Alpha (and to less degree beta) barium borate crystals can be used as neutron detectors.
Barium borate can be prepared by reaction of an aqueous solution
Aqueous solution
An aqueous solution is a solution in which the solvent is water. It is usually shown in chemical equations by appending aq to the relevant formula, such as NaCl. The word aqueous means pertaining to, related to, similar to, or dissolved in water...
of boric acid
Boric acid
Boric acid, also called hydrogen borate or boracic acid or orthoboric acid or acidum boricum, is a weak acid of boron often used as an antiseptic, insecticide, flame retardant, as a neutron absorber, and as a precursor of other chemical compounds. It exists in the form of colorless crystals or a...
with barium hydroxide
Barium hydroxide
Barium hydroxide is the chemical compound with the formula Ba2. Also known as baryta, it is one of the principal compounds of barium. The white granular monohydrate is the usual commercial form.-Preparation:...
. The prepared γ-BBO contains water of crystallization
Water of crystallization
In crystallography, water of crystallization or water of hydration or crystallization water is water that occurs in crystals. Water of crystallization is necessary for the maintenance of crystalline properties, but capable of being removed by sufficient heat...
that can not be completely removed by drying at 120 °C. Dehydrated γ-BBO can be prepared by heating to 300-400 °C. Calcination
Calcination
Calcination is a thermal treatment process applied to ores and other solid materials to bring about a thermal decomposition, phase transition, or removal of a volatile fraction. The calcination process normally takes place at temperatures below the melting point of the product materials...
at about 600-800 °C causes complete conversion to β-BBO. BBO prepared by this method does not contain trace amounts of BaB2O2
Barium borate is used as a flux
Flux (metallurgy)
In metallurgy, a flux , is a chemical cleaning agent, flowing agent, or purifying agent. Fluxes may have more than one function at a time...
in some barium titanate
Barium titanate
Barium titanate is the inorganic compound with the chemical formula BaTiO3. Barium titanate is a white powder and transparent as larger crystals...
and lead zirconate EIA Class 2 dielectric
EIA Class 2 dielectric
The EIA Class 2 dielectric materials are ceramic dielectric materials used in ceramic capacitors.The EIA Class 2 dielectrics in general are usually based on formulas with high content of barium titanate , possibly mixed with other dielectric electroceramics. Due to its piezoelectric properties,...
ceramic
Ceramic
A ceramic is an inorganic, nonmetallic solid prepared by the action of heat and subsequent cooling. Ceramic materials may have a crystalline or partly crystalline structure, or may be amorphous...
formulations for ceramic capacitor
Ceramic capacitor
In electronics, a ceramic capacitor is a capacitor constructed of alternating layers of metal and ceramic, with the ceramic material acting as the dielectric. The temperature coefficient depends on whether the dielectric is Class 1 or Class 2...
s, in amount of about 2%. The barium-boron ratio is critical for flux performance; BaB2O2 content adversely affects the performance of the flux.
Beta barium borate
Beta Barium Borate
Beta barium borate is a crystal frequently used for frequency mixing and other nonlinear optics applications...
crystals for nonlinear optics can be grown from fluxed melt of BBO, sodium oxide
Sodium oxide
Sodium oxide is a chemical compound with the formula Na2O. It is used in ceramics and glasses, though not in a raw form. Treatment with water affords sodium hydroxide....
and sodium chloride
Sodium chloride
Sodium chloride, also known as salt, common salt, table salt or halite, is an inorganic compound with the formula NaCl. Sodium chloride is the salt most responsible for the salinity of the ocean and of the extracellular fluid of many multicellular organisms...
.
Barium borate-fly ash
Fly ash
Fly ash is one of the residues generated in combustion, and comprises the fine particles that rise with the flue gases. Ash which does not rise is termed bottom ash. In an industrial context, fly ash usually refers to ash produced during combustion of coal...
glass
Glass
Glass is an amorphous solid material. Glasses are typically brittle and optically transparent.The most familiar type of glass, used for centuries in windows and drinking vessels, is soda-lime glass, composed of about 75% silica plus Na2O, CaO, and several minor additives...
can be used as radiation shielding. Such glasses are superior in performance to concrete
Concrete
Concrete is a composite construction material, composed of cement and other cementitious materials such as fly ash and slag cement, aggregate , water and chemical admixtures.The word concrete comes from the Latin word...
and to other barium borate glasses.