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Barium Fluoride (BaF2)

Barium Fluoride (BaF2) Data Sheet     ♦ Barium Fluoride (BaF2) MSDS

Barium Fluoride is used in spectroscopic components. Barium Fluoride is often suitable for applications in the passive IR band (8 to 14 μm) and is often used as a viewport window for thermography. For an equivalent thickness the transmission extends approximately 1 micron further into the IR than Calcium Fluoride. Windows intended primarily for IR use and noted as having IR polish may have restricted transmission in the VUV being made from lower purity BaF2 crystal.

The highest quality Barium Fluoride also has application as the fastest known scintillator material and is used in High Energy Physics Experiments.

 

Transmission Range : 0.15 to 12 μm (Note: IR grade may have restricted performance in UV)
Refractive Index : 1.45 at 5 μm (1)
Reflection Loss : 6.5% at 5 μm (2 surfaces)
Absorption Coefficient : 3.2 x 10-4 cm-1 @ 6 μm
Reststrahlen Peak : 47 μm
dn/dT : -15.2 x 10-6/°C (2)
dn/dμ = 0 : 1.95 μm
Density : 4.89 g/cc
Melting Point : 1386°C
Thermal Conductivity : 11.72 W m-1 K-1 @ 286 K
Thermal Expansion : 18.1 x 10-6/°C @ 273 K
Hardness : Knoop 82 with 500g indenter (4)
Specific Heat Capacity : 410 J Kg-1 K-1 (3)
Dielectric Constant : 7.33 at 1 MHz
Youngs Modulus (E) : 53.07 GPa (3)
Shear Modulus (G) : 25.4 GPa (3)
Bulk Modulus (K) : 56.4 GPa
Elastic Coefficients : C11 = 89.2 C12 = 40.0 C44 = 25.4 (2)
Apparent Elastic Limit : 26.9 MPa (300psi) (4)
Poisson Ratio : 0.343
Solubility : 0.17g/100g water at 23°C
Molecular Weight : 175.36
Class/Structure : Cubic CaF2, Fm3m, (111) cleavage

 

Not all crystal is manufactured from the highest grade of chemical; for IR grade optics a lower specification of raw material is adequate and reduces cost, however the transmission in the UV may be restricted.

To download this data or our MSDS safety data sheet as a pdf, please click on the links at the top of the page.  To expand the transmission graphs, please click on the image.

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µm   Noµm   Noµm   No
0.1408    1.8150 0.1452    1.7820 0.1477    1.7670
0.1500    1.6780 0.2000    1.557 0.2652    1.5122
0.2803    1.5066 0.2893    1.5039 0.2967    1.5019
0.3021    1.5004 0.3130    1.4978 0.3254    1.4952
0.3403    1.4925 0.3466    1.4915 0.3610    1.4894
0.3663    1.4887 0.4046    1.4844 0.5461    1.4759
0.5893    1.4744 0.6438    1.4730 0.6563    1.4727
0.7065    1.4718 0.8521    1.4699 0.8944    1.4694
1.0140    1.4685 1.1287    1.4678 1.3673    1.4667
1.5295    1.4661 1.6810    1.4656 1.7012    1.4655
1.9701    1.4647 2.3254    1.4636 2.6738    1.4623
3.2434    1.4602 3.4220    1.4594 5.1380    1.4501
5.5490    1.44732 6.2380    1.4422 6.6331    1.4390
7.0442    1.4353 7.2680    1.4331 9.7240    1.4051
10.346    1.3936

Barium Fluoride is grown by vacuum Stockbarger technique. Unlike CaF2, BaF2 is not found in the native state and all material must be synthesised chemically making BaF2 relatively expensive to produce. Barium Fluoride cleaves easily and is highly susceptible to thermal shock. It polishes well and can be etched (5).

Not all crystal is manufactured from the highest grade of chemical; for IR grade optics lower specification is adequate and reduces cost, however the transmission in the UV and VUV is restricted.

The highest purity Barium Fluoride VUV material can be qualified as fast scintillator grade. (6)


REFERENCES:
(1) Handbook Optical Constants, ed Palik, V3, ISBN 0-12-544423-0
(2) I.H.Malitson; J.Opt.Soc.Am. Vol52, p1377, 1962
(3) D.Girlich; Elastic Constants of BaF2; Phys.Rev. Vol135, p1826, 1964
(4) S.Ballard et al; J.Opt.Soc.Am. Vol42, p684, 1952
(5) US patent. Chemical polish. 4,040,896 1977
(6) M.Laval et al; Nu. Insts.Meth, V206 p169, 1983

WEBLINKS:
Wikipedia.org - Has an entry with further information on Barium Fluoride.