Barium Fluoride (BaF2)

Barium Fluoride is used for optical windows, lenses and prisms. The transmission range is 0.2μm - 11μm. Barium fluoride is grown by vacuum Stockbarger technique. Polishing is quicker than calcium fluoride using diamond pastes but is less easy to obtain free of sleeks. Barium fluoride is less resistant to attack by water than Calcium Fluoride. Pronounced water attack occurs at 500 °C, but the material can be used to 800 °C in a dry environment. The material is relatively hard but is highly sensitive to thermal shock.

Maximum available size: 200 mm, Dia x 50 mm Thickness

Specifications of BaF2
Transmission Range 0.13 to 10μm
Refractive Index 1.4626 at 2.6μm
Reflection Loss 6.8% at 2.6μm (2 surfaces)
Restrahlen Peak 47μm
dn/dT -15.2 x 10-6/ °C
Density 4.89 g/cm3
Melting Point 1280 °C
Thermal Conductivity 11.72 W/(m K) at 13 °C
Thermal Expansion 18.1 x 10-6/ °C at -100 to +200 °C
Hardness Knoop 82 kg/mm2 with 500g indenter
Specific Heat Capacity 410 J/(kg K) at 27 °C
Dielectric Constant 7.33 at 2MHz
Young's Modulus (E) 53.07 GPa
Shear Modulus (G) 25.4 GPa
Bulk Modulus (K) 56.4 GPa
Elastic Coefficients C11=89.2MPa C12=40.0Mpa C44=25.4MPa
Apparent Elastic Limit 26.89 MPa
Poisson Ratio 0.343