Zinc Sulphide Multispectral (Zinc Sulfide) (ZnS)
ZnS Multispectral (water-clear) is used for IR windows and lenses in the thermal band (8 to 14 μm) where maximum transmission and lowest absorption is required. Also selected for use where visible alignment is an advantage.
♦ Zinc Sulfide Visible Transmission data table ©2020. Open source for use with acknowledgement to Crystran Ltd.
|Transmission Range :||0.37 to 13.5 μm|
|Refractive Index :||2.20084 at 10 μm (1)|
|Reflection Loss :||24.7% at 10 μm (2 surfaces)|
|Absorption Coefficient :||0.0006 cm-1 at 3.8 μm|
|Reststrahlen Peak :||30.5 μm|
|dn/dT :||+38.7 x 10-6 /°C at 3.39 μm|
|Density :||4.09 g/cc|
|Melting Point :||1827°C (See notes below)|
|Thermal Conductivity :||27.2 W m-1 K-1 at 298K|
|Thermal Expansion :||6.5 x 10-6 /°C at 273K|
|Hardness :||Knoop 160 with 50g indenter|
|Specific Heat Capacity :||515 J Kg-1 K-1|
|Dielectric Constant :||88|
|Youngs Modulus (E) :||74.5 GPa|
|Shear Modulus (G) :||n/a|
|Bulk Modulus (K) :||n/a|
|Elastic Coefficients :||Not Avalailable|
|Apparent Elastic Limit :||68.9 MPa (10,000 psi)|
|Poisson Ratio :||0.28|
|Solubility :||65 x 10-6 g/100g water|
|Molecular Weight :||97.43|
|Class/Structure :||HIP polycrystalline cubic, ZnS, F42m|
To download this data or our MSDS safety data sheet as a pdf, please click on the links at the top of the page. To expand the transmission graphs, please click on the image.
Zinc Sulphide is produced by synthesis from Zinc vapour and H2S gas, forming as sheets on Graphite susceptors. Zinc Sulphide is microcrystalline in structure, the grain size being controlled to produce maximum strength. Multispectral grade is then Hot Isostatically Pressed (HIP) to improve the mid IR transmission and produce the visibly clear form. Single crystal ZnS is available, but is not common.
Zinc Sulphide oxidizes significantly at 300°C, exhibits plastic deformation at about 500°C and dissociates about 700°C. For safety, Zinc Sulphide windows should not be used above 250°C in normal atmosphere.
(1) Refractive Indices of Zinc Sulfide in the 0.405 - 13µm range. Mary Debenham (NPL) Applied OPtics / Vol 23, No 14 / July 1984