Germanium is lustrous, hard, grayish-white solid metalloid in the carbon group, chemically similar to its group neighbors tin and silicon. The purified germanium is a 'p-type' semiconductor material. The conductivity depends largely on added impurities. It has the same cubic crystal structure as diamond.
It has a high refractive index and is high transparency to infrared radiation. Germanium is a semiconductor and is one of the purest metals on earth (99.99999999999%).
1. Ge is used mainly in three applications: optical fiber, infrared optics, and catalyst in PET synthesis.
2. Optical fiber: In the form of GeCl4, GeO2 is deposited in the core of the fiber. GeO2 has a high refractive index and a low optical dispersion.
3. Infrared optics: Ge is used as lenses or windows. It is used in thermal imaging cameras, hot-spot detection mobile night vision applications.
4. Catalyst: GeO2 is used as a catalyst for the synthesis of polyethylene terephthalate (PET) used to make bottles.
5. Ge is also used electronic applications such as LEDs.
6. A niche application is ultra-high purity single crystal germanium. This is the most pure metal on earth and is used in gamma radiation detectors.