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Germanium, Ge, 32
Semi-metal
1211.4 K (938.3 °C)
3106 K (2830 °C)
Diamond structure
5.323 g/cm³ (at 20 °C)
6,0
50 Ω-cm (at 20 °C)
Physical properties
Germanium is a white-grey, shiny metallic semi-metal that is hard but brittle. It has a high density, chemical resistance and resistance to environmental influences.
It is permeable to infrared radiation, but blocks UV light. Of all infrared-transmitting materials, it has the lowest optical dispersion so that images remain particularly clear. Germanium also has the highest refractive index of all elements and refracts light more strongly than other materials - a major advantage for optical applications.
These properties make it possible to specifically control the refraction of light, which is why germanium dioxide (GeO₂) is incorporated into optical glass to increase the refraction of light or elemental germanium is used directly as a lens material. This makes germanium ideal for use in microscopes, wide-angle lenses and infrared and thermal imaging lenses.
Characteristic properties
The density of the element is lower in the solid state than in the liquid state, so molten germanium takes up less space than the same mass in the solid state. Only a few other elements exhibit this unusual behavior, including antimony, bismuth, gallium, lithium, silicon and tellurium.
Meaning and applications
Discovered in Germany in 1886 by chemist Clemens Alexander Winkler, the semimetal plays an important role in civil, industrial and military applications. The world's first germanium-based transistor was developed in 1947, so the semi-metal helped usher in the modern age of electronics.
Later largely displaced by silicon, germanium is now experiencing a technological renaissance through its use in silicon-germanium chips. These chips are used in modern electronics, for example in high-speed processors, fiber optic networks and high-frequency components. Germanium is also an indispensable raw material for modern communication and energy technologies.
According to the Fraunhofer Institute, demand could increase eightfold by 2035, particularly due to the global expansion of fiber optic communication and the spread of the Internet of Things (IoT).
In esotericism and homeopathy, germanium has gained a certain popularity as a so-called „active ingredient“ and is sold as colloidal germanium, for example. However, the semi-metal is not approved as a food supplement in the EU and taking it can pose serious health risks.