ZnS materials have two grades and can be use in imaging systems. Regular grade material is grown by the chemical vapor deposition process. This material is often used in the 3um to 5 um and 8um to 12 um region. It has reasonable hardness and is moderately priced.
Multi Spectral grade ZnS (CLEARTRAN ZnS) is treated after growth to eliminate microscopic voids and defects which occur in the regular grade, thus extending the usefulness of this material to include the visible region.
Compared with zinc selenium (ZnSe), zinc sulfide is lower priced and harder, more resistant to inclement weather, with fracture strength two times that of zinc selenium, thus making it an ideal material for production of missile radome and infrared winder for military aircrafts.
Physical and chemical properties
|
|
CVD zinc sulfide |
Multi Spectral CVD zinc sulfide |
|
Density (g.cm-3@298k) |
4.09 |
4.09 |
|
Specific resistance (Ω.cm) |
~1012 |
~1013 |
|
Melting point (℃) |
1827 |
|
|
Chemical purity (%) |
99.9996 |
99.9996 |
|
Thermal expansion coefficient (1/k) |
6.6×10-6@273k |
6.3×10-6@273k |
|
|
7.3×10-6@373k |
7.0×10-6@373k |
|
Thermal conductivity (j/k.m.s) |
16.7@298k |
27.2@298k |
|
Thermal capacity (j/g.k) |
0.469@298k |
0.515@298k |
|
Knoop hardness (kg/mm2) |
200-235 |
160 |
|
Bending strength (MPa) |
103 |
|
|
Young's modulus (GPa) |
74.5 |
74.5 |
|
Poissons ratio |
0.29 |
0.28 |
Optical properties
|
CVD zinc sulfide |
Multi Spectral CV zinc sulfide |
|
|
Transmission wavelength range |
1.0μm-14μm |
0.37μm-14μm |
|
Refractivity unevenness, △n/n |
<3×[email protected]μm |
<0.2×[email protected]μm |
|
Absorption coefficient (1/cm) |
||
|
Thermal optical coefficient, dn/dt (1/k, |
4.6×[email protected]μm |
5.43×[email protected]μm |
|
298-358k) |
||
|
4.3×[email protected]μm |
4.21×[email protected]μm |
|
|
4.1×[email protected]μm |
3.87×[email protected]μm |
Change of refractivity n as a function of wavelength
CVD ZnS (20℃):
|
Wavelength (μm) |
Refractivity (n) |
Wavelength (μm) |
Refractivity (n) |
|
0.62 |
2.355 |
9.80 |
2.203 |
|
1.00 |
2.292 |
10.60 |
2.192 |
|
3.80 |
2.253 |
11.40 |
2.180 |
|
5.00 |
2.246 |
12.20 |
2.167 |
|
7.00 |
2.232 |
13.80 |
2.132 |
|
9.00 |
2.212 |
14.20 |
2.126 |
Multi Spectral CVD zinc sulfide (CLEARTRAN ZnS)(20℃)
|
Wavelength (μm) |
Refractivity (n) |
Wavelength (μm) |
Refractivity (n) |
|
0.40 |
2.545 |
8.00 |
2.223 |
|
1.01 |
2.292 |
9.00 |
2.213 |
|
2.06 |
2.264 |
10.00 |
2.201 |
|
3.50 |
2.255 |
11.25 |
2.183 |
|
4.50 |
2.250 |
12.00 |
2.171 |
|
5.00 |
2.247 |
13.00 |
2.153 |
Specifications
|
Material |
CVD ZnS |
|
Dimension Tolerance |
+0.0/-0.1mm |
|
Thickness Tolerance |
±0.2mm |
|
Clear Aperture |
>90% |
|
Parallelism |
<1arc minutes |
|
Surface Quality |
60/40 or better |
|
Flatness |
<λ /2@633nm or better |
|
Chamfer |
Protected <0.5mmx45deg |
|
Coating |
None, per your request |
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