Zinc Sulphide is produced by synthesis from zinc vapour and H2S gas (chemical vapor desposition (CVD) process), forming as sheets on graphite substrates.
CVD-ZnS exhibits exceptional fracture strength, hardness and chemical inactivity leading to its frequent choice for military applications or other harsh environments.
Tydex produces optical componenst from both CVD-ZnS grades - IR grade (IR-ZnS) and multicspectral (water-clear) grade (MS-ZnS).
IR-ZnS is often used in the 8 to 12 microns region. Its high resistance to rain erosion and high-speed dust and particulate abrasion makes it particularly suitable for exterior IR windows for varios demanding applications.
MS-ZnS is treated by a hot isostatic press (HIP) process. Under intense heat and pressure, defects within the crystalline lattice are virtually eliminated, leaving a water-clear material with minimal scatter and high transmission characteristics from 0.4 to 12 microns.
Physical and Chemical Properties of ZnS
Parameter
|
IR-ZnS |
MS-ZnS |
| Density @ 300 K, g/cm3 |
4.09 |
| Melting point, K |
1830 |
| Thermal Conductivity @ 298 K , J/( K x m x s) |
19.0 |
27.2 |
Heat Capacity, 1/K @ 298 K, J/(g x K)
|
7.85 |
Thermal Expansion Coefficient 1/K @ 298 K
|
0.112 |
0.124 |
| Hardness (Knoop, indentor 50 g), kg/mm2 |
200-230 |
160 |
| Youngs Modulus (Е), GPa |
74.5 |
Poisson's Ratio
|
0.29 |
0.28 |
Modulus of Rupture, MPa
|
@ 298K |
103.4 |
68.9 |
| @ 933K |
160 |
160 |
Solubility
|
Нерастворим в воде |
|
Optical Properties
| Parameter |
IR-ZnS |
MS-ZnS |
Thermo-optic Coefficient,
(dn/dT)@298 K, 1/K |
@0.633 μm |
6.4 x 10-5 |
5.4 x 10-5 |
| @1,15 μm |
4.2 x 10-5 |
5.0 x 10-5 |
| @3,39 μm |
4.6 x 10-5 |
4.6 x 10-5 |
| @10,6 μm |
6.6 x 10-5 |
4.6 x 10-5
|
| Reflection loss @ 10.6 μm (2 surfaces), % |
24.7 |
| Index of Reflection Homogeneity (dn/n)@0.633 μm |
5.0 x 10-5 |
|
Refractive Index
| λ, μm |
n |
| IR-ZnS |
MS-ZnS |
|
0.5
|
2.4190
|
2.4130
|
0.5461
|
2.3910
|
2.3884 |
0.7
|
2.3320
|
2.3310
|
1.0
|
2.2920 |
2.2916
|
3.0
|
2.2570 |
2.2577
|
4.0
|
2.2520 |
2.2523
|
5.0
|
2.2460 |
2.2466
|
8.0
|
2.2233 |
2.2233
|
9.0
|
2.2120 |
2.2129
|
10.0
|
2.2005 |
2.2008
|
11.8
|
2.1730
|
2.1730
|
12.0
|
2.1710
|
2.1710
|
13.0
|
2.1525
|
2.1525
|
|
Fig. 1. Transmission spectra of CVD - ZnS windows of both grades.
Thicknesses are specified in mm.
Tydex offers optics from CVD-ZnS with the following limations in overal dimentions:
- diameters: 2-200mm;
- maximal thickness: 12mm (for meniscus shapes should be discussed additionally).
Please pay attention that this article is only for your information. We do not supply CVD-ZnS in blanks or as raw material. Our standard products are finished (polished, coated) parts.
Please link the following chapter to get more detailed information about ZnS optics: ZnS optics.
