Germanium

Germanium is a chemical element with the symbol Ge. It is a metalloid, meaning it has properties intermediate between metals and nonmetals. Its appearance is a shiny grayish-white, and it is hard and brittle.

Germanium belongs to the carbon group in the periodic table, the same group that includes silicon and tin. Its most important property for industry is that it is a semiconductor—a material that conducts electricity moderately and can be controlled by adding small quantities of other elements (doping).

History of discovery

When Dmitri Mendeleev prepared the periodic table in the 1860s, he predicted the existence of a missing element he called 'eka-silicon', describing its properties. In 1886, the German chemist Clemens Winkler isolated this element from an ore called argyrodite and named it after his country, Germany. The properties found matched those predicted so closely that this confirmed the validity of the periodic table.

Extraction and production

Germanium is not abundant in the Earth's crust as a pure element; it is usually found in small quantities in zinc ores and in coal ash. Consequently it is mostly obtained as a byproduct from zinc extraction processes. It is then purified to extremely high levels before use in electronics.

Applications

The earliest transistors, made in the 1940s, were based on germanium, but silicon later replaced it in most electronic applications because silicon is more stable and has better heat resistance. Today germanium is used in optical fibres, infrared camera windows, high-efficiency solar cells, and as a catalyst in the production of PET plastic. It is also used in scientific detection equipment such as gamma-ray counters.