Фторид бария

Описание

Barium fluoride appears as colourless, odourless crystals/white powder and is slightly soluble in water but soluble in ethanol and methanol. When heated, barium fluoride decomposes and emits toxic fumes of fluorine and barium. Barium fluoride is used as a preopacifying agent and in enamel and glazing frits production. Its other use is in the production of welding agents (an additive to some fluxes, a component of coatings for welding rods and in welding powders). It is also used in metallurgy as a molten bath for refining aluminium.

Химические свойства

Barium fluoride, BaF2, is a white crystal or powder.Under the microscope crystals may be clear and colorless. Barium fluoride is used commercially in combination with other fluorides for arc welding (qv) electrode fluxes.

Физические свойства

Barium fluoride (BaF2), also known as barium(II) fluoride, is a solid which can also be a transparent crystal. Its molecular weight is 175.34 g/mol. It occurs in nature as the mineral “Frankdicksonite”. It occurs as a white powder with a melting point of 1290 and a boiling point of 2259°C. It is slightly soluble in water (0.159 at 0.0°C and 0.162 g/100 ml of water at 20°C). The solid generally assumes the fluorite structure, but when subjected to high pressure, changes to the PbCl2 structure. In the vapor phase, the BaF2 molecule is nonlinear with an F–Ba–F angle of approximately 108°C.

Использование

Barium Fluoride is used in ceramic flux, carbon brushes for electrical equipment, glass making, in the manufacture of other fluorides, crystals for spectroscopy, electronics and dry-film lubricants. Barium Fluoride is used in spectroscopic components. Barium Fluoride is often suitable for applications in the passive IR band (8 to 14 ?m) and is often used as a viewport window for thermography.

Профиль безопасности

A poison by ingestion and intraperitoneal routes. Moderately toxic by subcutaneous route. An experimental teratogen. See also FLUORIDES and BARIUM COMPOUNDS (soluble). When heated to decomposition it emits toxic fumes of F-.

Методы очистки

Wash it well with distilled H2O and dry it in a vacuum. Its solubility in H2O is 1.6g (10o), 1.6g (20o) and 1.62g (30o) per L, and is soluble in mineral acids and aqueous NH4Cl. It may be stored in glass bottles. [Kwasnik in Handbook of Preparative Inorganic Chemistry (Ed. Brauer) Academic Press Vol I p 234 1963.]

Структура и конформация

The space lattice of Barium fluoride (BaF2) belongs to the cubic system, and its calcium fluoride structure has a lattice constant of a=0.6187 nm and Ba–F=0.268 nm.