BaF2 (Barium Fluoride)

Barium Fluoride is used in spectroscopic components. Barium Fluoride is often suitable for applications in the passive IR band (8 to 14μm) 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. The highest quality Barium Fluoride also has application as the fastest known scintillator material and is used in High Energy Physics Experiments.

Physical and optical properties 

Transmission Range :	0.15 to 12 μm
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

Refractive Index 

No = Ordinary Ray

µm	No	µm	No	µm	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

Product Notes

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

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

 

 

Tags: BaF2 (Barium Fluoride)

---