Zinc selenide

Material
ZnSe

Zinc selenide (ZnSe) is a widely used material for optical components in the IR range. Unlike other materials such as Ge or Si, zinc selenide is also transparent in the visible range. It has a transmission of about 70% in the wavelength range between 0.6 µm and 20 µm. The material is easy to process, chemically inert and has a high resistance to thermal shock and environmental influences.

ZnSe is not a naturally occurring material and is grown by chemical vapor deposition (CVD).

Compared to zinc sulfide (ZnS), zinc selenide is softer and more susceptible to scratching. However, ZnSe has better absorption and refractive index homogeneity at a wavelength of 10.6 µm and is therefore used in 10.6 µm high-power lasers. Furthermore, the material is used in the wide IR range for night vision devices as well as lenses, windows and prisms.

 

Special care must be taken when machining ZnSe, as fumes generated during grinding and polishing of the material are toxic.

Properties
Optical and spectral properties
Transmission range in µm (minimum 10%)
0,48‐20
Transmission range in µm (minimum 50%)
0,5‐20
Refractive index @633nm
2,591

(2,403 @10,6µm)

Reflection losses in % at 1 surface
17,05 @10µm
Reflection losses, % for two surfaces
29,1 @10,6µm
dN/dT in 1/K
61 · 10-6 @10,6µm @298K
Physical properties
Density in g/cm3
5,27
Melting point in °C
subl. >500°C
Specific heat capacity in J/(kg · K)
339
Thermal conductivity in W/(m · K)
18
Thermal expansion in 1/K
7,1 · 10-6 @271K
Dielectric constant
9,12
Solubility in water in g/100g
insoluble
Mohs hardness
4
Knoop hardness in kg/mm²
110
Material type
polycrystalline, synthetic
Crystal type
cubic, zincblende structure
Crystal structure
F43m
Lattice constant in Å
a = 5,67
Elastic coefficient in GPa
C11 = 86,4

C12 = 51,5

C44 = 40,2

Young's Modulus (E) in Gpa
70,3
Shear Modulus (G) in GPa
28,9
Bulk Modulus (K) in GPa
63,1
Rupture Modulus in MPa
55
Apparent elastic limit in MPa
55,1
Poisson's ratio
0,3
Spectral properties
sample thickness: 2 mm
Optical Properties
Transmission range in µm @10% min. 0.48 - 20
Transmission range in µm @50% min. 0.5 - 20
Refractive index @ 633nm 2.5906
(2.4028 @10.6µm)
Reflection losses in % at 1 surface 17.05 @ 10µm
Reflection losses in % at 2 surfaces 29.1 @ 10.6µm
dn/dT in 1/K 61 · 10-6
Physical Properties
Density in g/cm³ 5.27
Melting point in °C Subl. @ >500
Specific heat capacity in J/(kg · K) 339
Thermal Conductivity in W/(m · K) 18
Thermal Expansion in 1/K 7.1 · 10-6 @ 271K
Dielectric constant 9.12
Solubility in water in g/100g unsoluble
Mohs hardness 4
Knoop hardness in kg/mm² 110
Material type Polycrystalline, synthetic
Crystal type cubic
Crystal structure F43m
Lattice constant in Å a = 5.67
Elastic coeficients in GPa C11 = 86.4
C12 = 51.5
C44 = 40.2
Young's Modulus (E) in GPa 70.3
Shear Modulus (G) in GPa 28.9
Bulk Modulus (K) in GPa 63.1
Rupture Modulus in MPa 55
Apparent elastic limit in MPa 55.1
Poisson ratio 0.3
Spectral Properties