Almaz Optics, Inc.
12 Chadsford Ct.  Marlton, NJ 08053, USA
Tel:  856 797-0491, Fax: 856 797-0228
e-mail: mail@almazoptics.com

 

































GERMANIUM, Ge

Germanium is most widely used for lenses and windows in IR systems operating in the 2 m - 12 m range. Its transmission is very temperature sensitive, becoming opaque near 100C. Environment does not cause problems because Germanium is inert, mechanically rugged, and fairly hard. Maximum available size: 100 mm Dia x 50 mm Thk.




Main Properties

Chemical Formula Ge
Crystal Form Poly or Single Crystal
Crystal Class Cubic
Lattice Constant, 5.66
Molecular Weight 72.60
Density, g/cm3 at 300 K 5.33
Dielectric Constant for 9.37 x 109 Hz at 300 K 16.6
Melting Temperature, K 1210
Thermal Conductivity, W/(m K) at 293 K 59
Thermal Expansion, 1/K at 298 K 6.1 x 10-6
Specific Heat, cal/(g K) at 273-373 K 0.074
Debye Temperature, K 370
Bandgap, eV 0.67
Solubility in water None
Knoop Hardness, kg/mm2 800
Mohs Hardness 6.3
Young's Modulus, GPa 102.66
Shear Modulus, GPa 67.04
Bulk Modulus, GPa 77.86
Poisson's Ratio 0.278

Refractive Index

Wavelength, m 2.06 2.15 2.44 2.58 3.00 3.42 4.36 6.24 8.66 9.72 11.04 13.02
Refractive Index 4.10 4.09 4.07 4.06 4.05 4.03 4.02 4.01 4.00 4.00 4.00 4.00