A soft, soluble, water-absorbent optical substance called sodium chloride (NaCl) is used to create prisms, lenses, and optical windows. It is perfect for lenses and other optical components in the UV and IR regions since it transmits light throughout a broad wavelength range of roughly 0.25 to 16 μm. NaCl components should be kept dry and used optimally to maintain a polished appearance. Alfa Chemistry can produce optical components utilizing NaCl material that are nearly any size and shape on demand. Contact us if you require assistance.
Advantages and Uses of Sodium Chloride Materials
NaCl is particularly well suited for Fourier Transform Infrared (FTIR) spectroscopy and high-power laser systems because of its low absorption. NaCl is a low-cost alternative to KBr for IR sampling. Its refractive index is very similar to that of KBr, thus providing good IR transmittance. However, depending on the crystal thickness, the spectral range coverage may be constrained since its long wavelength cutoff wavelength is larger than KBr. NaCl is stiffer and less hygroscopic than KBr, but can only be used with anhydrous solvents, glycerol, or alcohols. The material is capable of withstanding both mechanical and thermal shocks. It becomes more resistant to moisture with a protective layer.
NaCl has a maximum operating temperature of 400°C and requires protection from atmospheric conditions due to moisture degradation. Beware that NaCl materials can be polished to a high standard in humidity-controlled conditions. In order to keep the polished surface dry and protected from moisture, it must either be exposed to dry air or heated with a heating element. The shielding coating increases its moisture resistance. It has a soft texture that requires careful handling.
Spectral Range
- Short wavelength limit: 52600 cm-1 (1 mm)
- Long wavelength limit: 457 cm-1 (2 mm), 584 cm-1 (4 mm)
Properties of Sodium Chloride Materials
| Density | 2.17 g/cc |
| Molecular Weight | 58.45 |
| Solubility | 35.7g/100g water at 273K |
| Class/Structure | Cubic FCC, NaCl, Fm3m, (100) cleavage |
| Melting Point | 801 ℃ |
| Hardness | Knoop 18.2 in <100> with 200g indenter |
| Refractive Index | 1.49065 at 10.6 μm |
| Transmission Range | 0.2 ~ 15 μm |
| Reflection Loss | 7.5% at 10.6 μm |
| dn/dT | -40.83 x 10-6/℃ |
| Absorption Coefficient | 7x10-6 cm-1 at 1.06 μm |
| Reststrahlen Peak | 50.1 μm |
| Youngs Modulus (E) | 39.98 GPa |
| Shear Modulus (G) | 12.61 GPa |
| Bulk Modulus (K) | 24.42 GPa |
| Thermal Expansion | 44 x10-6/℃ |
| Thermal Conductivity | 6.49 W/m/K at 289K |
| Dielectric Constant | 5.9 at 1MHz |
| Specific Heat Capacity | 854 J Kg-1 K-1 |
| Poisson Ratio | 0.252 |
| Elastic Coefficients | C11=48.5; C12=12.3; C44=12.61 |
About refractive index parameters.
"No" means ordinary light.
| µm | No | µm | No | µm | No |
|---|---|---|---|---|---|
| 0.589 | 1.54427 | 0.640 | 1.54141 | 0.760 | 1.53682 |
| 0.884 | 1.53395 | 0.972 | 1.53253 | 1.054 | 1.53153 |
| 1.555 | 1.53815 | 2.074 | 1.52736 | 9.000 | 1.501 |
| 9.500 | 1.4998 | 10.600 | 1.49065 | 11.400 | 1.48476 |
| 12.500 | 1.47568 | 13.500 | 1.4666 | 14.600 | 1.45572 |
| 16.000 | 1.4399 | 17.800 | 1.41649 | 19.800 | 1.38559 |
| 20.570 | 1.3735 | 22.300 | 1.3403 |