A method for producing a tetrahydroborate is disclosed. The method includes a plasma treatment step of exposing a borate to a hydrogen plasma. The method also includes that the plasma treatment is performed using hydrogen plasma generated by microwave or RF excitation, and the plasma treatment is performed while heating the borate at a temperature between 40° C. and 300° C.

An effectively solvent-free alkali metal or alkali earth metal closo-borate salt is prepared in the presence of a non-aqueous solvent where the solvent can be removed to levels below one mole percent of the salt. The process involves the exchange of cations with a closo-borate anion via an acid-base process or a metathesis process. The solvent is removed from the alkali metal or alkali earth metal closo-borate salt by heating. The temperature can be greater than the melting point of the salt but lower than temperatures where decomposition occurs.

The present disclosure relates to a method for producing a tetrahydroborate, the method including a plasma treatment step of exposing a borate to a hydrogen plasma.

An effectively solvent-free alkali metal or alkali earth metal closo-borate salt is prepared in the presence of a non-aqueous solvent where the solvent can be removed to levels below one mole percent of the salt. The process involves the exchange of cations with a closo-borate anion via an acid-base process or a metathesis process. The solvent is removed from the alkali metal or alkali earth metal closo-borate salt by heating. The temperature can be greater than the melting point of the salt but lower than temperatures where decomposition occurs.

A mineralizer composition for Pidgeon silicothermic process for smelting magnesium consists of fluorite and a boron-containing compound. Amounts of the fluorite and the boron-containing compound meet the following equation:

M.sub.fluo-original=(1−x)M.sub.fluo+(m)(x)M.sub.B,

where, M.sub.fluo-original is a mass of the fluorite required in a conventional Pidgeon silicothermic process in which no boron-containing compound is introduced to replace a fraction or all of the total fluorite, M.sub.fluo is a mass of the fluorite in the composition, M.sub.B is a mass of the boron-containing compound in the composition, 0.5≤x≤1, and 2≤m≤8. A Pidgeon silicothermic process for smelting magnesium is also provided, which employs the mineralizer composition. The composition and process of the disclosure enable reduction and even avoidance of dust pollution caused by fluorite-containing magnesium slag.

A lubricant additive may be synthesized by forming a nanohybrid of a transition metal dichalcogenide and a metal borate, forming a base oil, and then dispersing the transition metal dichalcogenide into the base oil. An exemplary nanohybrid may be synthesized by forming a first solution by adding a borax solution to an aqueous solution of a metal source, forming a second solution by adding ethanol to the first solution, forming a mixture by mixing the transition metal dichalcogenide with the second solution, and heating the mixture at a temperature of 180° C. to 230° C. and a pressure of 5 to 20 bar under a nitrogen atmosphere.

A lubricant additive may be synthesized by forming a nanohybrid of a transition metal dichalcogenide and a metal borate, forming a base oil, and then dispersing the transition metal dichalcogenide into the base oil. An exemplary nanohybrid may be synthesized by forming a first solution by adding a borax solution to an aqueous solution of a metal source, forming a second solution by adding ethanol to the first solution, forming a mixture by mixing the transition metal dichalcogenide with the second solution, and heating the mixture at a temperature of 180° C. to 230° C. and a pressure of 5 to 20 bar under a nitrogen atmosphere.

Crystalline NH.sub.4Be.sub.2BO.sub.3F.sub.2 or Be.sub.2BO.sub.3F (abbreviated as BBF) has nonlinear optical effect, is not deliquescent in the air, is chemically stable. They can be used in a variety of nonlinear optical fields and will pioneer the nonlinear optical applications in the deep UV band.

A calcium metaborate birefringent crystal and a preparation method and use thereof, the crystal having a chemical formula of CaB.sub.2O.sub.4 and a molecular weight of 125.70, and belonging to the orthorhombic crystal system and space group Pbcn with unit-cell parameters a=11.60(4), b=4.28(8), c=6.21(6), and Z=4, wherein the calcium metaborate birefringent crystal is a negative biaxial crystal with a transmission range of 165-3400 nm and a birefringence between 0.09-0.36; the crystal is applicable to infrared-visible-ultraviolet-deep ultraviolet bands, and is grown by a melt method, a flux method, a Bridgman method or a heat exchange method; the crystal obtained by the method of the present invention is easy to grow and easy to process; and can be used for making polarizing beam-splitting prisms.

A calcium metaborate birefringent crystal and a preparation method and use thereof, the crystal having a chemical formula of CaB.sub.2O.sub.4 and a molecular weight of 125.70, and belonging to the orthorhombic crystal system and space group Pbcn with unit-cell parameters a=11.60(4), b=4.28(8), c=6.21(6), and Z=4, wherein the calcium metaborate birefringent crystal is a negative biaxial crystal with a transmission range of 165-3400 nm and a birefringence between 0.09-0.36; the crystal is applicable to infrared-visible-ultraviolet-deep ultraviolet bands, and is grown by a melt method, a flux method, a Bridgman method or a heat exchange method; the crystal obtained by the method of the present invention is easy to grow and easy to process; and can be used for making polarizing beam-splitting prisms.