Germanium (Ge)

Crystallographic

Syngony	Cubic
Symmetry Class	m3m
Lattice Constants	a = 5.657 Å c = a
Cleavability	(111), perfect

 

Optical

Refractive Index at n10.6	4.0034
Refractive Index at n8.0 - n12.5	0.0036
Thermal Coefficient of Refractive Index at 3.39 microns for ±60 °C	35 - 40 x 10-5
Transmission Range, microns	2 - 17

 

Thermal

Thermal Linear Expansion, °C-1 for ±60 °C	(5.1 ... 5.8) x 10-6
Thermal Conductivity, W/(m * °C) at 27 °C	59.8
Specific Heat Capacity, J/(kg * °C)	0.310
Melting Point, °C	937
Absorbance m (l), cm -1
at 10.6 microns	0.027

 

Mechanical

Density, g/cm3 at 25 °C	5.33
Mohs Hardness	6
Vickers Microhardness, Pa	900 x 107
Constants of Elastic Compliance, Pa-1	S11 = 9.69 x 10-12 S12 = -2.65 x 10-12 S44 = 14.89 x 10-12
Young Modulus (E), Pa
in <100> direction	10.32x 1010
in <111> direction	15.56 x 1010
Shear Modulus (G), Pa
in <100> direction	6.72 x 1010
in <111> direction	4.67 x 1010
Poisson Ratio	0.278

 

Chemical

Molecular Weight	72.61
Solubility
in water, gram/100 cm3	insoluble

 

Ref. Index vs. Wavelength l

Wavelength, Microns	Refractive Index
2.0	4.1079
3.0	4.0446
4.0	4.0242
5.0	4.0153
6.0	4.0106
7.0	4.0076
8.0	4.0053
9.0	4.0047
10.0	4.0040
11.0	4.0031
12.0	4.0029
12.5	4.0024
15.0	4.0017

 

Internal Transmittance

Wavelength, Microns	Internal Transmittance
3.0	0.97
5.0	0.97
6.0	0.97
7.0	0.97
8.0	0.97
9.0	0.97
10.0	0.96
12.0	0.70
15.0	0.56

Source: Emsley, J. (1998) The Elements (3rd Edition)

Custom sizes and specifications are available on request.