Physical and optical properties
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Transmission Range :
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1.8 to 23 μm (1)
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Refractive Index :
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4.0026 at 11 μm (1)(2)
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Reflection Loss :
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53% at 11 μm (Two surfaces)
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Absorption Coefficient :
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<0.027 cm-1 @ 10.6 μm
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Reststrahlen Peak :
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n/a
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dn/dT :
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396 x 10-6 /°C (2)(6)
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dn/dμ = 0 :
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Almost constant
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Density :
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5.33 g/cc
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Melting Point :
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936 °C (3)
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Thermal Conductivity :
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58.61 W m-1 K-1 at 293K (6)
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Thermal Expansion :
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6.1 x 10-6/°C at 298K (3)(4)(6)
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Hardness :
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Knoop 780
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Specific Heat Capacity :
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310 J Kg-1 K-1 (3)
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Dielectric Constant :
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16.6 at 9.37 GHz at 300K
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Youngs Modulus (E) :
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102.7 GPa (4) (5)
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Shear Modulus (G) :
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67 GPa (4) (5)
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Bulk Modulus (K) :
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77.2 GPa (4)
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Elastic Coefficients :
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C11=129; C12=48.3; C44=67.1 (5)
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Apparent Elastic Limit :
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89.6 MPa (13000 psi)
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Poisson Ratio :
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0.28 (4) (5)
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Solubility :
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Insoluble in water
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Molecular Weight :
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72.59
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Class/Structure :
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Cubic Diamond, Fd3m
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Product Notes
Germanium is grown using the Czochralski technique by a small number of manufacturers in Belgium, USA, China and Russia. The refractive index of Germanium changes rapidly with temperature and the material becomes opaque at all wavelengths a little above 350K as the band gap floods with thermal electrons.
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