Sodium chloride



Sodium chloride Sodium Chloride (NaCl) is commonly used for optical components in wide spectrum band from the ultraviolet to the infrared, since it is transparent over the entire range of wavelengths (about 0.25µm to 16µm). Sodium Chloride can be used at temperatures up to 400°C. The material is sensitive to thermal shock.


Sodium Chloride is hygroscopic and highly soluble in water. That's why it must be kept in a dry environment or protected against moisture degradation of polished surfaces. The material can be polished to a high standard under humidity-controlled conditions.


Sodium Chloride is commonly used for optical windows, lenses, prisms and other optical items in the range from the ultraviolet to the infrared. It is one of the most useful materials for IR spectroscopic components and optical items for Fourier transform infrared (FTIR) spectroscopy. Due to its low absorption Sodium Chloride is mainly used in high power laser systems.

Optical Properties
Transmission range in µm @10% min. 0.17 - 23
Transmission range in µm @50% min. 0.18 - 20
Refractive index @ 633nm 1.54159
(1.49065 @10.6µm)
Reflection losses in % at 1 surface 3.93 @ 10µm
Reflection losses in % at 2 surfaces 7.6 @ 10.6µm
dn/dT in 1/K -36 · 10-6
Physical Properties
Density in g/cm³ 2.164
Melting point in °C 801
Specific heat capacity in J/(kg · K) 870
Thermal Conductivity in W/(m · K) 6.49
Thermal Expansion in 1/K 44 · 10-6
Dielectric constant 5.9
Solubility in water in g/100g 36 @ 25°C
Mohs hardness 3
Knoop hardness in kg/mm² 18.2 (<100>)
Material type Single crystal, synthetic
Crystal type cubic face-centered
Crystal structure cF8
Lattice constant in Å a = 5.6
Elastic coeficients in GPa C11 = 49.1
C12 = 12.8
C44 = 12.8
Young's Modulus (E) in GPa 39.98
Shear Modulus (G) in GPa 12.61
Bulk Modulus (K) in GPa 24.42
Rupture Modulus in MPa 2.4
Apparent elastic limit in MPa 3.9
Poisson ratio 0.26
Spectral Properties