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Potassium bromide

Material
KBr

 

Potassium bromide (KBr) is characterized by high transparency in the wavelength range between 0.25 µm and 26 µm. It can be used at temperatures above 300 °C and shows no optical absorption in the areas of high transmission. Potassium chloride is hygroscopic and highly soluble in water. For these reasons, it must be stored in a dry environment or protected against moisture by a special protective coating. Its chemical, optical and mechanical properties make potassium bromide a useful material for components of IR spectroscopy and beam splitters for CO2 lasers.


Properties
Optical Properties
Transmission range in µm @10% min. 0.2 - 25
Transmission range in µm @50% min. 0.23 - 25
Refractive index @ 633nm 1.55655
(1.537 @10µm)
Reflection losses in % at 1 surface 4.34 @ 10µm
Reflection losses in % at 2 surfaces 8.3 @ 10.6µm
dn/dT in 1/K -40.83 · 10-6
Physical Properties
Density in g/cm³ 2.7533
Melting point in °C 730
Specific heat capacity in J/(kg · K) 435
Thermal Conductivity in W/(m · K) 4.8
Thermal Expansion in 1/K 43 · 10-6
Dielectric constant 4.9
Solubility in water in g/100g 67.8 @ 25°C
Mohs hardness 1.5
Knoop hardness in kg/mm² 7 (<100>)
Material type Single crystal, synthetic
Crystal type cubic face-centered
Crystal structure Fm3m
Lattice constant in Å a = 6.598
Elastic coeficients in GPa C11 = 34.5
C12 = 5.4
C44 = 5.08
Young's Modulus (E) in GPa 26.8
Shear Modulus (G) in GPa 5.08
Bulk Modulus (K) in GPa 15.03
Rupture Modulus in MPa 3.3
Apparent elastic limit in MPa 3.3
Poisson ratio 0.3
Spectral Properties