Germanium (Ge) is useful for ATR prisms, CO ₂ laser optics, optical coatings for beam splitters and other IR optical applications. This material is somewhat brittle and tends to chip and spall.

 

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Optical Properties - Germanium (Ge) Optical Crystals

Transmission Range: 1.8µm to 23µm
Refractive Index: 4.0
Reflection Loss: 52.9 @ 10.6µm (2 surfaces)
dN/dT: 396 x 10^-6/°C

Physical Properties-- Germanium (Ge) Optical Crystals

Melting Point: 936° C
Hardness (Knoop): 550 psi
Young's Modulus: 102.7 GPa (100)
Modulus of Rupture: 7000 psi
Structure: Cubic

Chemical Properties- Germanium (Ge) Optical Crystals

Solubility: Insoluble in water. Soluble in hot H₂SO₄ and aqua-regia.