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Barium Fluoride (BaF2)

Barium fluoride (BaF2) is a solid which can be a transparent crystal. It occurs in nature as the mineral frankdicksonite.

The solid adopts the fluorite structure and at high pressure the PbCl2 structure.In the vapor phase the BaF2 molecule is non-linear with an F-Ba-F angle of approximately 108°. This is an exception to VSEPR theory which would predict a linear structure. Ab initio calculations have been cited to propose that contributions from d orbitals in the shell below the valence shell are responsible.Another proposal is that polarisation of the electron core of the barium atom creates an approximately tetrahedral distribution of charge that interacts with the Ba-F bonds.

Application: Barium Fluoride is transparent from the ultraviolet to the infrared, from 150–200 nm to 11–11.5 μm, and can be used as a material to make optical components such as lenses. It is used eg. in windows for infrared spectroscopy, in particular in the field of fuel oil analysis. Its transmittance at 200 nm is relatively low (0.60), but at 500 nm it goes up to 0.96–0.97 and stays at that level until 9 μm, then it starts falling off (0.85 for 10 μm and 0.42 for 12 μm). The refractive index is about 1.46 from 700 nm to 5 μm

Barium fluoride is also a common, very fast (one of the fastest) scintillator for the detection of X-rays, gamma rays or other high energy particles. One of its applications is the detection of 511 keV gamma photons in positron emission tomography; other material used in this application is eg. bismuth germanate. It responds also to alpha and beta particles, but, unlike most scintillators, it does not glow in ultraviolet light . It can be also used for detection of high-energy (10–150 MeV) neutrons, and use pulse shape discrimination techniques to separate them from simultaneously occurring gamma photons.

When heated to 500 °C, it gets corroded by water, but in dry environment it can be used up to 800 °C. Prolonged exposure to moisture degrades transmission in the vacuum UV range. It is less resistant to water than calcium fluoride, but is the most resistant of all the optical fluorides to high-energy radiation, though its far ultraviolet transmittance is lower than theirs. It is quite hard, very sensitive to thermal shock and fractures quite easily.

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.

Base infomation

Molecular formula: BaF2

Molar mass: 175.34 g/mol

Appearance: white cubic crystals

Density: 4.893 g/cm3

Melting point: 1368 °C

Boiling point: 2260 °C

Solubility in water: 0.16 g/100 mL (20 °C)

Solubility: soluble in methanol, ethanol

Crystal structure: Fluorite (cubic)

Space group: Fm3m

Barium Fluoride (BaF2) Sputtering Targets

Purity---99.9%,99.95%

Refractive Index/Transparence Wave Band ---1.47 / 0.15~15

Density---4.9 g/ cm3

Shape --- Discs, Plate, Step (Dia 300mm,,  Thickness 1mm)

                 Rectangle, Sheet,  Step (Length 1000mm, Width 300mm, Thickness 1mm)

                 Tube( Diameter< 300mm,  Thickness >2mm )

Application --- Possible low index film.

Barium Fluoride (BaF2) Evaporation Materials 

Purity--- 99.9%,99.99% Density @ 293 K--- 4.83 g/cm3

Shape--- White transparent granules, Cylinders, Pellets, Irregular Pieces,Solid substance, Custom-Made

Dimension---1-3mm, 4-10mm, Custom-Made

Melting Point--- 1280 °C Boiling Point--- 2137 °C 

Evaporation temperature---Vapour pressure, at 1130 ℃ 1 Pa, at 1262 ℃ 10 Pa
Solubility---
0.12 g/100 g H2O (25℃)

Coefficient of linear thermal expansion ---2.03×10-5/K
Specific heat capacity--- 0.406 KJ/KG.K
Hardness ---(acc. to Mohs) 3, (acc. to knoop) 82 Kg/mm2
Properties of thin film---
   Transmission range ~ 220~11000nm
   Refractive index at 500nm 1.48, at 2800nm 1.46, at 10600nm 1.40
Hints on evaporation---

   Evaporation with molybdenum,tantalum , platinum boat or electron-beam gun.
   Substrate temperature ~100 ~ 300℃
   Evaporation temperature ~1300 ~ 1500℃

Application---Multi-layer coatings in the IR and anti-reflection coatings in the IR.

Barium Fluoride (BaF2)  Powder

Purity---99.9%,99.99%  Shape --- colorless, little cube crystal

Density - - 4.89 g/ cm 3

Application --- Brush of motor, optical glass, optical fibrin, coating material, enamel, antiseptic, or insecticide.

 

 

 

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