Germanium (Ge) - Properties, Applications

Topics Covered

Chemical Properties
Physical Properties
Mechanical Properties
Thermal Properties


Germanium is a chemical element with Ge as its symbol. It belongs to group 14 of the periodic table and its atomic number is 32.

Germanium was first located in a rare mineral called argyrodite. However, today it is primarily obtained from the smelting of zinc ores and as a byproduct of burning certain types of coal.

Germanium has a diamond-like crystalline structure which is hard, lustrous, gray-white, and brittle. It is known to be stable in air and water, and is not affected by alkalis and acids with the exception of nitric acid.

Chemical Properties

The chemical properties of germanium are provided in the table below.

Chemical Data
CAS number 7440-56-4
Thermal neutron cross section 2.5 barns/atom
Ionic radius 0.530 Å
Electronegativity 2.01
X-ray absorption edge 1.116 Å

Physical Properties

The following table discusses the physical properties of germanium.

Properties Metric Imperial
Density 5.323 g/cm3 0.1923 lb/in3
Melting point 937°C 1719°F
Boiling point 2830 °C 2830°F

Mechanical Properties

The mechanical properties of germanium are tabulated below.

Properties Metric Imperial
Tensile strength 135-150 MPa 19.5801-21.7557 ksi
Poisson’s ratio 0.3 0.3
Modulus of elasticity 130 GPa 18900 ksi
Shear modulus 50 GPa 7250 ksi

Thermal Properties

The thermal properties of germanium are tabulated below.

Properties Metric Imperial
Thermal expansion co-efficient (@20-°C/68°F) 6.10 µm/m°C 3.39 µin/in°F
Thermal conductivity 64 W/mK 444 BTU in/hr.ft².°F


Germanium is largely used in the semiconductor industry. The following are the other application areas of germanium:

  • To manufacture alloys
  • Electronics and solar electric components
  • As a phosphor in fluorescent lamps

Germanium and germanium oxide are used in infrared optical instruments and infrared detectors. Germanium compounds are being researched for killing some types of bacteria and for use in chemotherapy.

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