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Potassium Bromide (KBr) Optical Material

Potassium bromide is a non-glass, inorganic optical material. It has a moderately low density among the non-glass optical ceramics in the database. The graph bars on the material properties cards below compare potassium bromide 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

24 GPa 3.4 x 106 psi

Poisson's Ratio


Shear Modulus

7.0 GPa 1.0 x 106 psi

Thermal Properties

Melting Onset (Solidus)

730 °C 1350 °F

Specific Heat Capacity

450 J/kg-K 0.11 BTU/lb-°F

Thermal Conductivity

4.8 W/m-K 2.8 BTU/h-ft-°F

Thermal Expansion

39 µm/m-K

Electrical Properties

Dielectric Constant (Relative Permittivity) At 1 MHz


Electrical Dissipation At 1 MHz


Otherwise Unclassified Properties


2.8 g/cm3 170 lb/ft3

Light Transmission Range

0.22 to 26 µm

Refractive Index


Common Calculations

Stiffness to Weight: Axial

4.7 points

Stiffness to Weight: Bending

35 points

Thermal Diffusivity

3.9 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

CRC Materials Science and Engineering Handbook, 4th ed., James F. Shackelford et al. (editors), 2015