Zinc Selenide (ZnSe)

Zinc Selenide is used for optical windows, lenses, mirrors and prisms particularly for infrared applications. The transmission range is 0.5μm - 22μm. Used for high power CO2-laser optics at 10.6micronsZinc Selenide is produced by synthesis from zinc vapour and H2Se gas, forming as sheets on graphite susceptors. It is microcrystalline in structure, the grain size being controlled to produce maximum strength. Single crystal ZnSe is available, but is not common but has been reported as having lower absorption and thus more effective for CO2optics.

Specifications of ZnSe
Transmission Range 0.6 to 21.0μm
Refractive Index 2.4028 at 10μm
Reflection Loss 29.1% at 10.6μm (2 surfaces)
Absorption Coefficient 0.0005cm-1 at 10.6μm
Restrahlen Peak 45.7microns
dn/dT +61 x 10-6/°C at 10.6μm at 298K
dn/dμ = 0 5.5μm
Density 5.27g/cm3
Melting Point 1525°C (dissociates about 700°C)
Thermal Conductivity 18 W/(m K) at 298K
Thermal Expansion 7.1 x 10-6/ °C at 273K
Hardness Knoop 120 with 50g indenter
Specific Heat Capacity 339 J · kg-1 · K-1
Bulk Modulus (K) 40 GPa
Young's Modulus (E) 67.2 GPa
Apparent Elastic Limit 55.1 MPa (8,000psi)
Poisson Ratio 0.28