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Potassium Bromide (KBr) Optical Material

Potassium bromide is a non-glass, inorganic optical material. It has a moderately low density relative to other 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).

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 m2/s

Followup Questions

Further Reading

Handbook of Optical Constants of Solids, Edward D. Palik (editor), 1998

Handbook of Optical Materials, Marvin J. Weber, 2003