Barium Fluoride (BaF2)

Barium Fluoride



Barium Fluoride is commonly used for optical components in expanded spectrum band from ultraviolet to infrared regions, since it is transparent over an extremely wide range of wavelengths (from 0.15-0.20 µm to 11-11.5 µm). Barium Fluoride (BaF2) transmittance at 200 nm is relatively low (~60%), but at 500 nm Barium Fluoride (BaF2) goes up to 96%-97% and stays at that level until 9 µm, then it starts falling off (85% for 10 µm and 42% for 12 µm).

BaF2 is hard but is very sensitive to thermal shock. In dry environment, BaF2 can be used up to 800 °C, but its resistance to water is less than that of Calcium Fluoride. That’s why it is corroded by water when it is heated to 500 °C. Nevertheless, BaF2 is the most resistant of all optical fluorides to high-energy radiation.


BaF2 is used for optical windows, lenses, prisms and other optical items in the range from the ultraviolet to the infrared. For an equivalent thickness the transmission extends approximately 1 micron further into the IR than Calcium Fluoride. In addition, BaF2 has application as the fastest known scintillator material and is used for production of fast-acting and radiation resistant scintillation detectors for positron-emission tomography, nuclear calorimetry, gamma-spectroscopy and for identification of charged particles, neutrons and Cherenkov counters.



We use for our Barium Fluoride (BaF2) optics high quality crystals grown by Czochralsky and Bridgman Methods and supply high transparent and low-loss BaF2 optical windows, prisms, lenses, achromatic lenses and other optical components. BaF2 is sold in two qualities (monodomain and polydomain) and in three grades – IR-, UV- and scintillator-grade.

Optical Properties
Transmission range in µm @10% min. 0.14 - 15
Transmission range in µm @50% min. 0.14 - 14
Refractive index @ 633nm 1.47326
Reflexion loss in % at 1 surface 3.4 @ 4µm
Reflexion loss in % at 2 surfaces 6.5 @ 5µm
dn/dT in 1/K -15.2 · 10-6
Physical Properties
Density in g/cm³ 4.89
Melting Point in °C 1368
Specific heat capacity in J/(kg · K) 410
Thermal Conductivity in W/(m · K) 10.9
Thermal Expansion in 1/K 18.4 · 10-6
Dielectric Constant 7.33
Solubility in water in g/100g 0.16 @ 25°C
Mohs hardness 3
Knoop hardness in kg/mm² 82
Material type Single crystal, synthetic
Crystal Type Cubic, CaF2 strukture
Crystal structure cF12
Lattice Constant in Å a = 6.2
Elastic Coefficients in GPa C11 = 91
C12 = 41.2
C44 = 25.3
Youngs's Modulus (E) in GPa 53.07
Shear Modulus (G) in GPa 25.4
Bulk Modulus (K) in GPa 57.8
Rupture Modulus in MPa 26.9
Apparent elastic limit in MPa 26,9
Poissonzahl 0,31
Spectral Properties
Availiable Products

Impex supplies following barium fluoride optics:

BaF2 blanks
BaF2 windows
BaF2 lenses
BaF2 prisms

The following barium fluoride optics are in stock:

BaF2 blanks
BaF2 windows