Magnesium Fluoride crystal is used as a lens, prism and window for wavelength from 110nm to 7.5μm. It is a most suitable material as window for ArF Excimer Laser, for the reason of its good transmission at 193nm. It is also effective as an, optical polarizing element in the ultraviolet region. Any more MgF2 crystal has fine grain, which is appropriate as a vacuum evaporation coating materials.

Optical Properties

Transmission Range110 nm to 7.5 μm

Transmittance>90% at 193 nm to 6 μm

Refractive IndexNo=1.37608; Ne=1.38771 (at 0.7μm)

Reflection Loss5.2% at 0.6 μm (both surfaces)

Residual Radiation Peak20 nm

Absorption Coefficient0.04 cm-1 at 2.7 μm

dn/dT2.3 x 10-6 /℃ parallel c-axis

1.7 x 10-6 /℃ perpendicular c-axis

Physical Properties

Density3.18 g/cm3

Melting Point1255℃

Thermal Conductivity0.3 Wm-1K-1 at 300K

Thermal Expansion13.7 x 10-6 /℃ parallel c-axis

8.9 x 10-6 /℃ perpendicular c-axis

Knoop Hardness415 with 100g indenter (kg/mm2)

Specific Heat Capacity1003 J/(kg.k)

Dielectric Constant1.87  at 1MHz parallel c-axis

1.45  at 1MHz perpendicular c-axis

Youngs Modulus (E)138.5 GPa

Shear Modulus (G)54.66 GPa

Bulk Modulus (K)101.32 GPa

Elastic CoefficientC11=164; C12=53; C44=33.7

C13=63; C66=96

Apparent Elastic Limit49.6 MPa (7200 psi)

Poisson Ratio0.276

Chemical Properties

Solubility0.0002 g/ 100g water at 20℃

Molecular Weight62.32

StructureTetragonal Crystal

Cleavage Plane(110)