Barium fluoride (BaF2) is a general-purpose optical window material that offers a wide range of transparency, from the ultraviolet to the long-wave infrared, with low reflectance loss and low dispersion. BaF2 single crystal is an intensively studied scintillator for the detection of gamma radiation due to its relatively high stopping power, radiation hardness and extremely fast response. BaF2 possesses the fast cross-luminescence component at 195 and 220 nm with a lifetime of several hundred picoseconds. However, this component coexists with slow one at 310 nm related to the self-trapped exciton (STE). BaF2 is a broad band gap crystal with Eg=10:9 eV. It is currently regarded as the fastest inorganic scintillator which has cross-luminescence bands peaked at 195 and 220 nm and a broad band peaking at about 300 nm due to self-trapped excitons. Much attention has been focused on the luminescent properties of rare earth ions activated BaF2.
Parameter
| Orientation | [100] or [111] < ±0.5° |
| Angle Tolerance | < 0.5° |
| Parallelism | <20〞 |
| Perpendicularity | 5ˊ |
| Surface Quality | 10-5 (MIL-O-13830A) |
| Wavefront Distortion | <λ/4@633 nm |
| Surface Flatness | <λ/8 @633 nm |
| Clear Aperture | >90% |
| Thickness/Diameter Tolerance | ±0.05 mm |
| Crystal System | Isometric |
| Habit | Cubic |
| Space Group | Fm3m(Oh5 |
| Lattice Constants | 6.2001 Å |
| Specific mass | 4.886 g/cm3 |
| Melting Point | 1354°C |
| Flexure Strength (MPa) | 27 |
| Tenacity | Brittle |
| Thermal Conductivity /(W·cm-1·K-1@25°C) | 0.07 |
| Specific Heat/ (J·g-1·K-1) | 1.003 |
| Thermal Expansion /（10-6·K-1@25°C ） | 13.7 |
| Hardness (kg/mm2@Knoop) | 78 |
| Young`s Modulus /GPa | 138.5 |
| Fracture | {111} and {100} |
| Transmission Range | 0.15 … 12 µm |
| Reflective Loss | 6 … 16%@0.2 … 10 µm |
| Thermo-optic coefficient（10-6·K-1@30…90°C ） | -18.8 |
| Poisson Ratio | 0.31 |
| Dielectric Constant | 7.33@f=2MHz |
| λ(μm) | n | λ(μm) | n | λ(μm) | n |
| 0.2 | 1.5573 | 4 | 1.4558 | 9 | 1.4144 |
| 0.5 | 1.4779 | 5 | 1.4511 | 10 | 1.4011 |
| 1 | 1.4686 | 6 | 1.4441 | 11 | 1.3865 |
| 2 | 14647 | 7 | 1.4357 | 12 | 1.3696 |
| 3 | 1.4612 | 8 | 1.4258 | 12.5 | 1.3585 |
| 15 | 1.305 |
- Excellent transmission from 150nm to 12um
- Chemically stable
- Low reflectance loss and low dispersion
- High stopping power, radiation hardness and extremely fast response
- Broad band gap
- Susceptible to thermal shock
- Possesses the fast cross-luminescence component at 195 and 220 nm with a lifetime of several hundred picoseconds
- Window and focusing mirror for deep uv and excimer lasers
- Scintillator,IR optics
- Inorganic scintillator for subnanosecond timing
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