In 1871 Mendeleev postulated the existence and properties of a hypothetical element situated between silicon and tin that he named eka-silicon. This element was eventually isolated by Winkler in 1886. He found it in a mineral while excavating a mine in the vicinity of Freiberg in Saxony. He gave it the name of his native country, Germania.
For a long time germanium remained a laboratory curiosity and found its use in multiple applications but was eventually superseded by silicon after a few decades.
- One of the most important properties of Germanium is its high refractive index, making it a very useful imaging component of IR systems.
- A very bright, hard, brittle grey metal that cannot be rolled or drawn.
- Crystallises in the face-centred cubic system, in which it forms covalent bonds (diamond structure).
- Germanium is an excellent semiconductor.
- GASIR® is transparent from 0.8 µm up to 16 µm and offers 8 times lower change of refractive index with temperature than germanium.
- Germanium's most important application is in the form of germanium tetrachloride for optical fibres.
- Applications in the field of infrared optics account for another sizeable part of germanium consumption. Here it is used in lenses or windows, given its high transparency to infrared radiation.
- Because germanium and gallium arsenide have very similar lattice constants, germanium substrates can be used to make gallium arsenide solar cells. The first two Mars Exploration Rovers and most satellites use triple junction gallium arsenide on germanium cells.
- Germanium is also used as a catalyst for the synthesis of polyethylene terephthalate (PET) used to make food containers and plastic bottles.
- High-purity germanium single crystals are used in the detection of γ-rays.
Germanium is mainly recycled from the production processes of various industries such as fibre optics, solar cells, LEDs and infrared optics. End-of-life recycling presents significant challenges due to the dissipative nature of some of the applications.