Potassium chloride (KCl) is used in IR spectroscopy as well as in high power CO2 laser applications. It refers to salt crystals (like KBr and NaCl). KCl is a soft and stable to thermal influence monocrystal. Due to material hygroscopicity the polished parts require storage in desiccator or in sealed package with silica gel in a warm room.
Application:
- IR spectroscopy
- CO2 laser optics
Product types:
- Plane-parallel windows and wedges
- Lenses
Specifications
Tab.1. Typical specification of KCl optical components
| Specification |
Typical |
State-of-the-art |
| Sizes |
See table in the article Plane Windows and Wedged Windows |
Up to 100 mm |
| Diameter tolerance, mm |
+0/-0.25 |
RFQ |
| Thickness tolerance, mm |
±0.25 |
RFQ |
| Thickness matching, mm |
— |
RFQ |
| Surface quality, scr/dig |
60/40 |
RFQ |
| Surface flatness, λ @ 633nm per inch* |
2 |
RFQ |
| Parallelism (wedge tolerance) |
5 arc min |
RFQ |
| Coating |
none |
protecting |
| Packaging |
Typak® |
|
|
Transmission Spectrum
The measurements were carried out on Perkin Elmer Lambda-35 spectrophotometer and on BrukerVertex-70 Fourier-spectrometer.
Tab.2. Refractive index
| λ, µm |
n |
| 0.20 |
1.7187 |
| 0.51 |
1.4962 |
| 1.18 |
1.4783 |
| 5.00 |
1.4705 |
| 6.00 |
1.4684 |
| 7.00 |
1.466 |
| 8.00 |
1.4629 |
| 9.00 |
1.4600 |
| 10.00 |
1.4564 |
| 11.00 |
1.4524 |
| 12.00 |
1.4480 |
| 13.00 |
1.4431 |
| 14.00 |
1.4378 |
| 15.00 |
1.4320 |
| 16.00 |
1.4256 |
| 17.00 |
1.4188 |
| 18.00 |
1.4113 |
| 19.00 |
1.4033 |
| 20.00 |
1.3947 |
| 21.00 |
1.3854 |
| 22.00 |
1.3754 |
| 23.00 |
1.3646 |
| 24.00 |
1.3530 |
| 25.00 |
1.3406 |
| 26.00 |
1.3272 |
| 27.00 |
1.3128 |
| 28.00 |
1.2973 |
|
Tab.3. Optical properties
| Transmission range, microns |
0.22-21 |
| Colour |
Colourless |
| Reflection losses @ 11 µm (2 surfaces), % |
8.3 |
| Absorption coefficient, @ 3.8 µm, 10-4 cm-1 |
1.6 |
| Restrahlen peak, μm |
63.1 |
| dN/dT, 10-6/C |
-33.2 |
|
Tab.4. Physical and mechanical properties
| Class / Structure |
Cubic FCC, NaCl type, Fm3m, (100) cleavage |
| Density @300K, g/cm3 |
1.98 |
| Molecular Weight |
74.55 |
| Melting Point, °C |
776 |
| Thermal Conductivity @322K, W/(mxK) |
6.53 |
| Thermal Expansion @300K, 10-6/C |
36 |
| Hardness, Knoop with 200g indenter |
in (100) |
9.3 |
| in (110) |
7.2 |
| Specific Heat Capacity, J/(kg×K) |
690 |
| Debye temperature, K |
235 |
| Dielectric Constant for 106 Hz @300K |
4.64 |
| Bandgap, eV |
8.5 |
| Young Modulus (E), GPa |
29.67 |
| Shear Modulus (G), GPa |
6.24 |
| Bulk Modulus (K), GPa |
17.36 |
| Elastic Coefficient |
C11 = 40.2 C12 = 6.7 C44 = 6.29 |
| Apparent Elastic Limit, MPa |
2.3 (330psi) |
| Poisson Ratio |
0.216 |
|
Tab.5. Chemical stability / Solubility
in water
(at 0 оС) |
34.7 g/100cm3
hygroscopic |
| in acids |
soluble |
| in organic solvents: |
|
| spirits |
insignificantly soluble |
|
Please pay your attention that this article is for your information only. We do not supply KCl in ingots as well as semi-finished products. Our standard products are polished parts.
For further information on our KCl optical components please see the following: Windows for IR-spectroscopy, Packaging or fill in our request form.
