Calcium Fluoride (CaF2) Optical Material
Calcium fluoride is a non-glass, inorganic optical material. It has a fairly high heat capacity and a moderately high melting temperature among non-glass optical ceramics. The graph bars on the material properties cards below compare calcium fluoride to other non-glass optical ceramics (top) and the entire database (bottom). A full bar means this is the highest value in the relevant set. A half-full bar means it's 50% of the highest, and so on.
Mechanical Properties
Elastic (Young's, Tensile) Modulus
80 GPa 12 x 106 psi
Knoop Hardness
160
Poisson's Ratio
0.26
Shear Modulus
34 GPa 4.9 x 106 psi
Thermal Properties
Melting Onset (Solidus)
1420 °C 2590 °F
Specific Heat Capacity
860 J/kg-K 0.21 BTU/lb-°F
Thermal Conductivity
9.7 W/m-K 5.6 BTU/h-ft-°F
Thermal Expansion
19 µm/m-K
Otherwise Unclassified Properties
Density
3.2 g/cm3 200 lb/ft3
Light Transmission Range
0.15 to 9.0 µm
Refractive Index
1.4
Common Calculations
Stiffness to Weight: Axial
14 points
Stiffness to Weight: Bending
45 points
Thermal Diffusivity
3.5 mm2/s
Followup Questions
Further Reading
Handbook of Optical Materials, Marvin J. Weber, 2003
Handbook of Optical Constants of Solids, Edward D. Palik (editor), 1998
Ceramics and Composites: Processing Methods, Narottam P. Bansal and Aldo R. Boccaccini (editors), 2012