May 2008

Germanium: not a houseplant

By D. Zlotnikov

Catalogued core samples are displayed at Tres Marias

Mention the word “germanium” and most people are likely to think that you’re mispronouncing the name of a popular houseplant rather than naming a distinguished member of the periodic table. For a mineral priced at more than $1,300/kg, surprisingly few people know what germanium is or why it’s important.  Nevertheless, numerous industries rely on this mystery mineral.

Germanium is primarily a byproduct of zinc ore processing. It is a hard, greyish-white element with a metallic lustre and is a semiconductor with electrical properties between those of a metal and an insulator.  Even though it was discovered in the late 1800s, a use for the mineral was not found until the mid-1940s, when it was used to make the first transistor. However, over the years, more uses were found for germanium.

Plastics: The largest portion of germanium (31 per cent) is consumed by the plastics industry, where the mineral is used as a catalyst in the manufacture of polyethylene terephthalate (PET). PET produced using germanium is much clearer than when other catalysts are used.

Fibre optics: The fibre-optics industry is the second biggest consumer of germanium at 24 per cent. Here it is used to enhance the optical properties of the silica fibres, especially in long-distance, transoceanic communications.

Infrared sensing: A close third (23 per cent), germanium is employed by the infrared sensing sector primarily for military use. As it turns out, germanium is transparent to infrared emissions, which makes it an ideal choice for use in lenses in infrared sensors and night-vision equipment. In recent years the automotive industry has also expressed an interest in these products, installing infrared sensors in some luxury cars as a nighttime aid for the drivers. But it is the military applications that have caused germanium to be added to the U.S. National Defense Stockpile — a list of “strategic and critical materials” that were deemed valuable enough that their supply had to remain uninterrupted in the case of war.

Microelectronics: Perhaps the best known use of germanium is in the realm of microelectronics. Microchip manufacturers are already experimenting with germanium as a replacement for silicon that, while cheaper, is approaching its physical limits in terms of conductivity. Most promising so far is the silicon-germanium combination, which improves on the chips’ properties and allows for even greater processing power.

Satellite and solar panels: Germanium is also used in the satellite and solar panel manufacturing sectors, where its light weight and efficiency in converting heat to electricity make it ideal for use in photovoltaic cells. Rising energy costs and growing public interest have certainly made the mineral an attractive option for many companies.

Still, despite the fame, the photovoltaic and electronics markets account for only 12 per cent of global consumption, though the photovoltaic portion is expected to grow.

Thanks to Keith Knobelauch of Murdock Capital Partners Corp. for his assistance with this overview.

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