Magnesium fluoride (MgF2) is a UV to IR transmitting material that is widely used in UV wavelength applications and has excellent high transmittance in the vacuum UV spectrum. MgF2 can tolerate high-stress settings thanks to its superior mechanical strength. Additionally, MgF2 can be utilized to create polarized wave sheets because of its birefringence. Alfa chemistry can custom fabricate optical components of virtually any shape and size using MgF2 materials. Please get in touch with us if you require assistance.
Advantages and Uses of Magnesium Fluoride Materials
MgF2 has been successfully used in high-energy lasers, particularly those that operate in the UV region. The material transmits effectively up to and past the hydrogen Lyman-alpha line (121 nm) in the VUV spectrum. The vacuum Stockbarger method is used to develop MgF2 in ingots of varying sizes. It has a tough nature and can be polished very well. It can be used to the highest standards as a result.
Fig 1. The transmittance of MgF2 (the black and red line represent mid-infrared transmittance with 50 nm pre-layer and without pre-layer, respectively.) (Zhang G, et al. 2019)
MgF2 is commonly supplied with an optical axis that is cut perpendicular to the window surface and is mildly birefringent. Alfa Chemistry commonly cuts and positions the window to produce minimal birefringence using an optical axis perpendicular to a surface parallel to the (001) plane (c-axis) [001]. There is an a-cut available that is equivalent to a b-cut if maximum birefringence is required.
- Very hard and robust
- Resistant to mechanical and thermal shock
- The only optical material that combines a broad spectral transmission band with the phenomenon of birefringence
Properties of Magnesium Fluoride Materials
| Density | 3.18 g/cc |
| Molecular Weight | 62.32 |
| Solubility | 0.0002 g/100g water |
| Class/Structure | Tetragonal, can cleave on c-axis |
| Melting Point | 1255 ℃ |
| Hardness | Knoop 415 |
| Refractive Index | No 1.413 at 0.22 μm |
| Transmission Range | 0.12 ~ 7 μm |
| Reflection Loss | 5.7% at 0.22 μm |
| Reststrahlen Peak | 20 μm |
| Absorption Coefficient | 40 x 10-3 cm-1 at 2.7 μm |
| dn/dT | 2.3 (para) 1.7 (perp) at 0.4 μm |
| Youngs Modulus (E) | 138 GPa |
| Shear Modulus (G) | 54.66 GPa |
| Bulk Modulus (K) | 101.32 GPa |
| Apparent Elastic Limit | 49.6 MPa (7200 psi) |
| Thermal Expansion | 13.7 (para) 8.9 (perp) x 10-6/K |
| Thermal Conductivity | 21 (para) 33.6 (perp) W/m/K at 300K |
| Dielectric Constant | 4.87 (para) 5.45 (perp) at 1MHz |
| Specific Heat Capacity | 1003 J Kg m-1 K-1 |
| Poisson Ratio | 0.276 |
| Elastic Coefficients | C11=140, C12=89, C44=57, C13=63, C66=96 |
About refractive index parameters.
"No" means ordinary light, "Ne" means extraordinary light.
| µm | No | Ne | µm | No | Ne | µm | No | Ne |
|---|---|---|---|---|---|---|---|---|
| 0.1137 | 1.781 | 0.115 | 1.742 | 0.118 | 1.680 | |||
| 0.1198 | 1.651 | 0.121 | 1.628 | 1.632 | 0.130 | 1.566 | 1.568 | |
| 0.140 | 1.510 | 1.523 | 0.150 | 1.480 | 1.494 | 0.160 | 1.461 | 1.475 |
| 0.170 | 1.448 | 1.462 | 0.180 | 1.439 | 1.453 | 0.190 | 1.431 | 1.444 |
| 0.200 | 1.423 | 1.437 | 0.220 | 1.413 | 1.426 | 0.248 | 1.403 | 1.416 |
| 0.257 | 1.401 | 1.414 | 0.266 | 1.399 | 1.412 | 0.280 | 1.396 | 1.409 |
| 0.300 | 1.393 | 1.405 | 0.330 | 1.389 | 1.402 | 0.337 | 1.389 | 1.401 |
| 0.350 | 1.387 | 1.400 | 0.355 | 1.386 | 1.399 | 0.400 | 1.384 | 1.396 |
| 0.546 | 1.379 | 1.390 | 0.700 | 1.376 | 1.388 | 1.087 | 1.373 | 1.385 |
| 1.512 | 1.370 | 1.382 | 2.000 | 1.368 | 1.379 | 2.500 | 1.364 | 1.375 |
| 3.030 | 1.360 | 1.370 | 3.571 | 1.354 | 1.364 | 4.000 | 1.349 | 1.359 |
| 4.546 | 1.341 | 1.350 | 5.000 | 1.334 | 1.343 | 5.556 | 1.324 | 1.332 |
| 6.060 | 1.314 | 1.321 |
Reference
- Zhang G, et al. (2019). "Influences of Oxygen Ion Beam on the Properties of Magnesium Fluoride Thin Film Deposited Using Electron Beam Evaporation Deposition." Precision Engineering. Coatings. 9(12): 834.