Germanium tetrachloride
Encyclopedia
Germanium tetrachloride is a colourless liquid used as an intermediate in the production of purified germanium
metal. In recent years, GeCl4 usage has increased substantially due to its use as a reagent for fiber optic
production.
is from treating flue-dusts of zinc- and copper-ore smelters, although a significant source is also found in the ash from the combustion of certain types of coal called vitrain
. Germanium tetrachloride is an intermediate for the purification of germanium metal or its oxide, GeO2.
Germanium tetrachloride can be generated directly from GeO2 by dissolution of the oxide in concentrated hydrchloric acid. The resulting mixture is fractionally distilled to purify and separate the germanium tetrachloride from other products and impurities. The GeCl4 can be rehydrolyzed with deionized water to produce pure GeO2, which is then reduced under hydrogen to produce germanium metal.
Production of GeO2, however, is dependent on the oxidized form of germanium extracted from the ore. Copper-lead-sulfide and zinc-sulfide ores will produce GeS2, which is subsequently oxidized to GeO2 with an oxidizer such as sodium chlorate
. Zinc-ores are roasted and sintered and can produce the GeO2 directly. The oxide is then processed as discussed above.
and low optical dispersion, used for wide camera lens, microscopy, and for the core of fiber-optic lines. See Optical fiber
for specifics on the manufacturing process. Overall, silicon tetrachloride
, SiCl4 and germanium tetrachloride, GeCl4 are introduced with oxygen
into a hollow glass preform, which is carefully heated to allow for oxidation of the reagents to their respective oxides and formation of a glass mixture. The GeO2 has a high index of refraction, so by varying the flowrate of germanium tetrachloride the overall index of refraction of the optical fiber can be specifically controlled. The GeO2 is about 4% by weight of the glass.
consumption of germanium is used for infrared optics technology and 50% for fiber-optics. Over the past 20 years, infrared use has consistently decreased; fiber optic demand, however, is slowly increasing. There is discussion on the over-production of fiber-optic networks and that 30-50% of current lines are unused dark fiber
, suggesting a future reduction in demand. Worldwide, demand is increasing dramatically as countries such as China are expanding fiber-optic based telecommunication throughout the country.
Germanium
Germanium is a chemical element with the symbol Ge and atomic number 32. It is a lustrous, hard, grayish-white metalloid in the carbon group, chemically similar to its group neighbors tin and silicon. The isolated element is a semiconductor, with an appearance most similar to elemental silicon....
metal. In recent years, GeCl4 usage has increased substantially due to its use as a reagent for fiber optic
Optical fiber
An optical fiber is a flexible, transparent fiber made of a pure glass not much wider than a human hair. It functions as a waveguide, or "light pipe", to transmit light between the two ends of the fiber. The field of applied science and engineering concerned with the design and application of...
production.
Production
Most commercial production of germaniumGermanium
Germanium is a chemical element with the symbol Ge and atomic number 32. It is a lustrous, hard, grayish-white metalloid in the carbon group, chemically similar to its group neighbors tin and silicon. The isolated element is a semiconductor, with an appearance most similar to elemental silicon....
is from treating flue-dusts of zinc- and copper-ore smelters, although a significant source is also found in the ash from the combustion of certain types of coal called vitrain
Vitrain
Vitrain is a type of coal. Its combustion leads to ash containing extractable levels of germanium compounds such as germanium dioxide....
. Germanium tetrachloride is an intermediate for the purification of germanium metal or its oxide, GeO2.
Germanium tetrachloride can be generated directly from GeO2 by dissolution of the oxide in concentrated hydrchloric acid. The resulting mixture is fractionally distilled to purify and separate the germanium tetrachloride from other products and impurities. The GeCl4 can be rehydrolyzed with deionized water to produce pure GeO2, which is then reduced under hydrogen to produce germanium metal.
Production of GeO2, however, is dependent on the oxidized form of germanium extracted from the ore. Copper-lead-sulfide and zinc-sulfide ores will produce GeS2, which is subsequently oxidized to GeO2 with an oxidizer such as sodium chlorate
Sodium chlorate
Sodium chlorate is a chemical compound with the chemical formula . When pure, it is a white crystalline powder that is readily soluble in water. It is hygroscopic. It decomposes above 250 °C to release oxygen and leave sodium chloride...
. Zinc-ores are roasted and sintered and can produce the GeO2 directly. The oxide is then processed as discussed above.
Application
Germanium tetrachloride is used almost exclusively as an intermediate for several optical processes. GeCl4 can be directly hydrolyzed to GeO2, an oxide glass with several unique properties and applications, described below:Fiber Optics
Most notable of GeO2 is its high index of refractionRefraction
Refraction is the change in direction of a wave due to a change in its speed. It is essentially a surface phenomenon . The phenomenon is mainly in governance to the law of conservation of energy. The proper explanation would be that due to change of medium, the phase velocity of the wave is changed...
and low optical dispersion, used for wide camera lens, microscopy, and for the core of fiber-optic lines. See Optical fiber
Optical fiber
An optical fiber is a flexible, transparent fiber made of a pure glass not much wider than a human hair. It functions as a waveguide, or "light pipe", to transmit light between the two ends of the fiber. The field of applied science and engineering concerned with the design and application of...
for specifics on the manufacturing process. Overall, silicon tetrachloride
Silicon tetrachloride
Silicon tetrachloride is the inorganic compound with the formula SiCl4. It is a colourless volatile liquid that fumes in air. It is used to produce high purity silicon and silica for commercial applications.-Preparation:...
, SiCl4 and germanium tetrachloride, GeCl4 are introduced with oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
into a hollow glass preform, which is carefully heated to allow for oxidation of the reagents to their respective oxides and formation of a glass mixture. The GeO2 has a high index of refraction, so by varying the flowrate of germanium tetrachloride the overall index of refraction of the optical fiber can be specifically controlled. The GeO2 is about 4% by weight of the glass.
Infrared
Germanium and its glass oxide, GeO2 are transparent to the infrared spectrum. The glass can be manufactured into IR windows and lenses, used for night-vision technology in the military and luxury vehicles. GeO2 is preferred over other IR transparent glasses because it is mechanically strong and therefore preferred for rugged military usage.Future
As of the year 2000, about 15% of United StatesUnited States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
consumption of germanium is used for infrared optics technology and 50% for fiber-optics. Over the past 20 years, infrared use has consistently decreased; fiber optic demand, however, is slowly increasing. There is discussion on the over-production of fiber-optic networks and that 30-50% of current lines are unused dark fiber
Dark fiber
A dark fiber or unlit fiber is an unused Optical fiber, available for use in fiber-optic communication.The term dark fiber was originally used when referring to the potential network capacity of telecommunication infrastructure, but now also refers to the increasingly common practice of leasing...
, suggesting a future reduction in demand. Worldwide, demand is increasing dramatically as countries such as China are expanding fiber-optic based telecommunication throughout the country.