Germanium (pronEng|dʒɚˈmeɪniəm) is a
chemical elementwith the symbol Ge and atomic number32. It is a lustrous, hard, silver-white metalloidin the carbon group, chemically similar to its group neighbors tinand silicon. Germanium has five naturally occurring isotopes ranging in atomic mass numberfrom 70 to 76. It forms a large number of organometalliccompounds, including tetraethylgermaneand isobutylgermane.
Because few minerals contain it in large concentration, germanium was discovered relatively late despite the fact that it is relatively abundant in the Earth's crust. In 1869,
Dmitri Mendeleevpredicted its existence and some of its properties based on its position on his periodic tableand called the element ekasilicon. Nearly two decades later, in 1886, Clemens Winklerfound it in the mineral argyrodite. Winkler found that experimental observations agreed with Mendeleev's predictions and named the element after his country, Germany.
Germanium is an important
semiconductormaterial used in transistors and various other electronic devices. Its major end uses are fiber-opticsystems and infrared optics, but is also used for polymerizationcatalysts, in electronics and in solar electric applications. Germanium is mined primarily from sphalerite, though it is also recovered from silver, lead, and copperores. Some germanium compounds, such as germanium chloride and germane, can irritate the eyes, skin, lungs, and throat.
In his report on "The Periodic Law of the Chemical Elements", in 1869,
Dmitri Mendeleevpredicted the existence of several unknown elements, including one filling a gap in the carbon family, between siliconand tin. [ cite journal| first = Masanori | last = Kaji |title = D. I. Mendeleev's concept of chemical elements and "The Principles of Chemistry"|journal=Bulletin for the History of Chemistry|volume=27|issue=1|pages=4–16|year=2002|url=http://www.scs.uiuc.edu/~mainzv/HIST/awards/OPA%20Papers/2005-Kaji.pdf| format=pdf|accessdate = 2008-08-20 ] Because of its position in the table, he called it "ekasilicon (Es)" and assigned it an atomic weightof 72.
In the summer of 1885, in a mine near
Freiberg, Saxony, a new mineral was found. It was named " argyrodite", because of its high silvercontent.Ref_label|A|a|none Clemens Winklerexamined this new mineral and was able to isolate an element similar to antimonyin 1886.cite journal | journal = Berichte der deutschen chemischen Gesellschaft | volume = 19 | issue = 1 | pages = 210–211 | title = Germanium, Ge, a New Nonmetal Element | language=German | first = Clemens | last = Winkler | authorlink = Clemens Winkler | year = 1887 | doi = 10.1002/cber.18860190156 | url = http://gallica.bnf.fr/ark:/12148/bpt6k90705g/f212.chemindefer | format= [http://dbhs.wvusd.k12.ca.us/webdocs/Chem-History/Disc-of-Germanium.html English translation] ] Before he published his results on the new element Winkler intended to name the element "neptunium", as the actual discovery of planet Neptunein 1846 had been preceded by mathematical prediction of its existence.Ref_label|B|b|none However, the name neptunium had already been given to an element (though not the element that today bears the name neptunium, discovered in 1940),Ref_label|C|c|none and instead, Winkler named the new metal "germanium" (from the Latin"Germania" for Germany) in honor of his fatherland. Because the element showed similarities with the elements arsenicand antimony, its place in the periodic table was under discussion, but the similarities between Mendeleev's ekasilicon and germanium confirmed its place. [cite journal | journal = The Manufacturer and Builder | url = http://cdl.library.cornell.edu/cgi-bin/moa/pageviewer?frames=1&coll=moa&view=50&root=%2Fmoa%2Fmanu%2Fmanu0018%2F&tif=00187.TIF | year = 1887| title = Germanium, a New Non-Metallic Element | pages =181| accessdate = 2008-08-20] With further material from 500 kg of ore from the mines in Saxony, Winkler could confirm the chemical properties of the new element in 1887.cite journal | first = Clemens | last = Winkler | title = Mittheilungen über das Germanium | journal = J. Prak. Chemie | volume= 34 | year = 1886 | pages=177–229 | doi = 10.1002/prac.18860340122 | url = http://gallica.bnf.fr/ark:/12148/bpt6k90797z/f185.table | language=German ] cite journal | first = Clemens | last = Winkler | journal = J. Prak. Chemie | volume = 36 | year = 1887 |pages = 177–209 | title = Mittheilungen über des Germanium. Zweite Abhandlung |doi = 10.1002/prac.18870360119 | url = http://gallica.bnf.fr/ark:/12148/bpt6k90799n/f183.table| accessdate = 2008-08-20| language=German ] [cite journal | first = O. | last = Brunck | title = Obituary: Clemens Winkler | journal = Berichte der deutschen chemischen Gesellschaft | volume= 39 | issue = 4 | year = 1886 | pages=4491–4548 | doi = 10.1002/cber.190603904164 | language=German ] He also determined an atomic weight of 72.32 by analyzing pure germanium tetrachloride (chem|GeCl|4), whilst Lecoq de Boisbaudrandeduced 72.3 by a comparison of the lines in the spark spectrumof the element. [cite journal | title = Sur le poids atomique du germanium | first = M. Lecoq | last = de Boisbaudran | journal = Comptes rendus | year = 1886 | volume = 103 |pages = 452 | url = http://gallica.bnf.fr/ark:/12148/bpt6k3059r/f454.table | accessdate = 2008-08-20| language=French]
Winkler was able to prepare several new compounds of germanium, including the fluorides, chlorides, sulfides, germanium dioxide, and
tetraethylgermanium, the first organogermane. With the physical data from these compounds—which corresponded with Mendeleev's predictions—it made the discovery an important confirmation of Mendeleev's idea of element periodicity. Here is a comparison between the prediction and Winkler's data:
Until the late 1930s, germanium was believed to be a poorly conducting metal.cite web|title=Germanium: From Its Discovery to SiGe Devices|author= Haller, E. E.| work=Department of Materials Science and Engineering, University of California, Berkeley, and Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, |url=http://www.osti.gov/bridge/servlets/purl/922705-bthJo6/922705.PDF| format=pdf| accessdate=2008-08-22] It did not become economically significant until after 1945, when its properties as a semiconductor were recognized as being valuable in electronics. It was only during World War II, in 1941, that germanium diodes began to supplant
vacuum tubes in electronic devices. [cite web| author = W. K. | url = http://select.nytimes.com/gst/abstract.html?res=F30715FE3F5B157A93C2A8178ED85F478585F9 | publisher = NY Times | year = 1953| title = Germanium for Electronic Devices| accessdate=2008-08-22] [cite web | url = http://www.computerhistory.org/semiconductor/timeline/1941-semiconductor.html | title = 1941 - Semiconductor diode rectifiers serve in WW II | publisher = Computer History Museum| accessdate=2008-08-22] Its first major use was the point contact Schottky diodes for radar reception during WWII. The first silicon-germaniumalloys were obtained in 1955. [cite web | url = http://www.sp.phy.cam.ac.uk/~SiGe/Silicon%20Germanium%20(SiGe)%20History.html | title = SiGe History | publisher = University of Cambridge| accessdate=2008-08-22] Before 1945, only a few hundred kilograms of the element were produced each year, but by the end of the 1950s, annual worldwide production had reached 40 metric tons.cite news|url=http://pubs.acs.org/cen/80th/print/germanium.html| year=2003| title=Germanium| first = Bethany | last = Halford| work= Chemical & Engineering News |publisher= American Chemical Society| accessdate=2008-08-22]
The development of the germanium
transistorin 1948 [cite journal | journal = Physical Reviews | volume = 74 | pages = 230–231 | title = The Transistor, A Semi-Conductor Triode |first = J. | last = Bardeen | coauthor = Brattain, W. H.| year = 1948 | doi = 10.1103/PhysRev.74.230 ] opened the door to countless applications of solid state electronics. [cite web | title = Electronics History 4 - Transistors | url = http://www.greatachievements.org/?id=3967 | publisher = National Academy of Engineering | accessdate=2008-08-22] From 1950 through the early 1970s, this area provided an increasing market for germanium, but then high purity siliconbegan replacing germanium in transistors, diodes, and rectifiers.cite journal|title=Germanium—Statistics and Information| author=U.S. Geological Survey | year=2008 | journal=U.S. Geological Survey, Mineral Commodity Summaries | url=http://minerals.usgs.gov/minerals/pubs/commodity/germanium/ |quote=Select 2008| accessday=2008-08-28] Silicon has superior electrical properties, but requires much higher purity—a purity which could not be commercially achieved in the early days. [cite journal|journal=IEEE Transactions on Electron Devices | volume = ED-23 | issue = 7 | year = 1976 | month = July | title = Single Crystals of Germanium and Silicon-Basic to the Transistor and Integrated Circuit | first = Gordon K. | last = Teal |pages = 621–639 | url=http://ieeexplore.ieee.org/iel5/16/31752/01478478.pdf|doi=10.1109/T-ED.1976.18464]
Meanwhile, demand for germanium in
fiber opticscommunication networks, infrared night visionsystems, and polymerization catalystsincreased dramatically. These end uses represented 85% of worldwide germanium consumption for 2000. The U.S. government even designated germanium as a strategic and critical material, calling for a 146 tons (132 t) supply in the national defense stockpile in 1987. Germanium differs from silicon in that the supply of silicon is only limited by production capacity, while that for germanium is limited by the shortage of exploitable sources. As a result, while silicon could be bought in 1998 for less than $10 per kg, the price of 1 kg of germanium was then almost $1800.
standard conditionsgermanium is a brittle, silvery-white, semi-metallic element. This form constitutes an allotropetechnically known as "α-germanium", which has a metallic luster and a diamond cubic crystal structure, the same as diamond. At pressures above 120 kbar, a different allotrope known as "β-germanium" forms, which has the same structure as β- tin. Along with silicon, gallium, bismuth, antimony, and water, it is one of the few substances that expands as it solidifies (i.e. freezes) from its molten state.
Germanium is a
semiconductor. Zone refiningtechniques have led to the production of crystalline germanium for semiconductors that has an impurity of only one part in 1010,cite web|url=http://periodic.lanl.gov/elements/32.html|publisher=Los Alamos National Laboratory|title=Germanium|accessdate=2008-08-28] making it one of the purest materials ever obtained. [cite book |title=The Primordial Universe: 28 June - 23 July 1999 |editor=Binetruy, B. |author=Chardin, B. |chapter=Dark Matter: Direct Detection |publisher=Springer |year=2001 |isbn=3540410465 |pages=308] The first metallic material becoming a superconductorin the presence of an extremely strong electromagnetic fieldwas a alloy of germanium with uranium and rhodium. The discovery was made in 2005. [cite journal | doi = 10.1126/science.1115498 | year = 2005|month=August | last =Lévy| first= F. | coauthors = Sheikin, I.; Grenier, B.; Huxley, Ad.|title=Magnetic field-induced superconductivity in the ferromagnet URhGe|volume=309|issue=5739|pages=1343–1346|pmid=16123293|journal=Science]
Pure germanium is known to spontaneously extrude very long
screw dislocations, referred to as "germanium whiskers". The growth of these whiskers is one of the primary reasons for the failure of older diodes and transistors made from germanium, as, depending on what they eventually touch, they may lead to an electrical short. [cite journal| title = Morphology of Germanium Whiskers | first = E. I. | last = Givargizov | journal = Kristall und Technik | volume = 7 | issue = 1–3 |doi = 10.1002/crat.19720070107| pages = 37–41| year = 1972]
Elemental germanium oxidizes slowly to GeO2 at 250 oC. [cite journal|doi=10.1016/S0169-4332(98)00251-7|title=KRXPS study of the oxidation of Ge(001) surface|year=1998|author=Tabet, N|journal=Applied Surface Science|volume=134|pages=275 ] Germanium is insoluble in dilute acids and alkalis but dissolves slowly in concentrated
sulfuric acidand reacts violently with molten alkalis to produce germanates (chem| [GeO|3|] 2−). Germanium occurs mostly in the oxidation state+4 although many compounds are known with the oxidation state of +2.Greenwood&Earnshaw] Other oxidation states are rare, such as +3 found in compounds such as Ge2Cl6, and +3 and +1 observed on the surface of oxides, [cite journal|doi=10.1016/S0368-2048(98)00451-4|title=XPS study of the growth kinetics of thin films obtained by thermal oxidation of germanium substrates|year=1999|author=Tabet, N|journal=Journal of Electron Spectroscopy and Related Phenomena|volume=101-103|pages=233] or negative oxidation states in germanes, such as -4 in chem|GeH|4. Germanium cluster anions, (Zintl ions), such as Ge42−, Ge94−, Ge92−, [(Ge9)2] 6− have been prepared by the extraction from e.g. alloys containing alkali metals and germanium in liquid ammonia in the presence of ethylenediamineor a cryptand. [cite journal|title=Oxidative Coupling of Deltahedral [Ge9] 4− Zintl Ions|first = Li | last = Xu | coauthors = Sevov, Slavi C.|journal=J. Am. Chem. Soc. | format = communication | year = 1999 | volume = 121| issue = 39 | pages = 9245–9246 | doi = 10.1021/ja992269s] The oxidation states of the element in these ions are not integers—similar to the ozonides O3-.
Two oxides of germanium are known:
germanium dioxide(chem|GeO|2, germania) and germanium monoxide, (chem|GeO).cite book | last = Holleman | first = A. F. | coauthors = Wiberg, E.; Wiberg, N. | title=Lehrbuch der Anorganischen Chemie, 102nd ed. | publisher=de Gruyter | year=2007 | isbn=978-3-11-017770-1 | oclc = 145623740 180963521 219549154] The dioxide, GeO2 can be obtained by roasting germanium sulfide(chem|GeS|2), and is a white powder that is only slightly soluble in water but reacts with alkalis to form germanates. The monoxide, (germanous oxide), can be obtained by the high temperature reaction of GeO2 with Ge metal. The dioxide (and the related oxides and germanates) exhibits the unusual property of having a high refractive index for visible light, but transparency to infraredlight. [cite journal | title = Infrared Transparent Germanate Glass-Ceramics | first = Shyam S. | last = Bayya | coauthors = Sanghera, Jasbinder S.; Aggarwal, Ishwar D.; Wojcik, Joshua A. | journal = Journal of the American Ceramic Society | volume = 85 | issue = 12 | pages= 3114–3116 | year = 2002] [cite journal | doi = 10.1007/BF00614256 | title = Infrared reflectance and transmission spectra of germanium dioxide and its hydrolysis products | year = 1975 |last = Drugoveiko | first = O. P. | journal = Journal of Applied Spectroscopy | volume = 22 | pages = 191 ] Bismuth germanate, Bi4Ge3O12, (BGO) is used as a scintillator.cite journal | title = A Bismuth Germanate-Avalanche Photodiode Module Designed for Use in High Resolution Positron Emission Tomography | last = Lightstone | first = A. W. | coauthors = McIntyre, R. J.; Lecomte, R.; Schmitt, D. | journal = IEEE Transactions on Nuclear Science| year = 1986 | volume =33 | issue= 1 | pages = 456–459 | doi =10.1109/TNS.1986.4337142] Binary compounds with other chalcogens are also known, such as the di sulfide(chem|GeS|2), di selenide(chem|GeSe|2), and the monosulfide (GeS), selenide (GeSe), and Telluride (GeTe). GeS2 forms as a white precipitate when hydrogen sulfide is passed through strongly acid solutions containing Ge(IV). The disulfide is appreciably soluble in water and in solutions of caustic alkalis or alkaline sulfides. Nevertheless, it is not soluble in acidic water, which allowed for Winkler to make the discovery of the element. [cite journal | first =Otto H. | last = Johnson | title = Germanium and its Inorganic Compounds | journal = Chem. Rev. | year = 1952 | volume= 3| pages=431 – 431 | doi = 10.1021/cr60160a002] By heating the disulfide in a current of hydrogen, the monosulfide (GeS) is formed. which sublimes in thin plates of a dark color and metallic luster, and is soluble in solutions of the caustic alkalis. Upon melting with alkaline carbonates and sulfur, germanium compounds form salts known as thiogermanates. [cite journal|doi=10.1039/a703634e|title=First synthesis of mesostructured thiogermanates|year=1997|last = Fröba | first = Michael |journal=Chemical Communications|pages=1729]
halidesare known. Under normal conditions GeI4 is a solid, GeF4 a gas and the others volatile liquids. For example germanium tetrachloride, GeCl4, is obtained as a colourless fuming liquid boiling at 83.1°C by heating the metal with chlorine. All the tetrahalides are readily hydrolysed to hydrated germanium dioxide. GeCl4 is used in the production of organogermanium compounds. All four dihalides are known and in contrast to the tetrahalides are polymeric solids. Additionally Ge2Cl6 and some higher compounds of formula GenCl2n+2 are known. The unusual compound Ge6Cl16 has been prepared that contains the Ge5Cl12 unit with a neopentanestructure. [cite journal | title = The Crystal Structure and Raman Spectrum of Ge5Cl12·GeCl4 and the Vibrational Spectrum of Ge2Cl6| last = Beattie | first = I.R. | coauthors = Jones, P.J.; Reid, G.; Webster, M.; | journal = Inorg. Chem. | volume = 37 | issue =23 | pages = 6032–6034 | year = 1998 | doi =10.1021/ic9807341 S0020-1669(98)00734-4] Germane(GeH4) is a compound similar in structure to methane. Polygermanes—compounds that are similar to alkanes—with formula GenH2n+2 containing up to five germanium atoms are known. The germanes are less volatile and less reactive than their corresponding silicon analogues. GeH4 reacts with alkali metals in liquid ammonia to form white crystalline MGeH3 which contain the GeH3− anion. The germanium hydrohalides with one, two and three halogen atoms are colorless reactive liquids.
organogermanium compoundwas synthesised by Winkler in 1887; the reaction of germanium tetrachloride with diethylzincyielded tetraethylgermane(chem|Ge(C|2|H|5|)|4). Organogermanes of the type R4Ge (where R is an alkyl) such as tetramethylgermane(chem|Ge(CH|3|)|4) and tetraethylgermane are accessed through the cheapest available germanium precursor germanium tetrachlorideand alkyl nucleophiles. Organic germanium hydrides such as isobutylgermane(chem|(CH|3|)|2|CHCH|2|GeH|3) were found to be less hazardous and may be used as a liquid substitute for toxic germanegas in semiconductorapplications. Many germanium reactive intermediates are known: germyl free radicals, germylenes (similar to carbenes), and germynes (similar to carbynes). [cite journal | title = Reactive intermediates in organogermanium chemistry | first = Jacques | last = Satge | journal = Pure & Appl. Chem. | volume = 56 | issue = 1 | pages = 137–150 | year =1984 | doi = 10.1351/pac198456010137] [cite journal | title = Organogermanium Chemistry| first = Denis | last = Quane | coauthors = Bottei, Rudolph S. | journal = Chemical Reviews | volume = 63 | issue = 4 | pages = 403–442 | year =1963 | doi = 10.1021/cr60224a004] The organogermanium compound 2-carboxyethylgermasesquioxanewas first reported in the 1970s, and for a while was used as a dietary supplement and thought to possibly have anti-tumor qualities.
Germanium has five naturally-occurring
isotopes, 70Ge, 72Ge, 73Ge, 74Ge, and 76Ge. Of these, 76Ge is very slightly radioactive, decaying by double beta decaywith a half-lifeof 1.58 × 1021 years. 74Ge is the most common isotope, having a natural abundanceof approximately 36%. 76Ge is the least common with a natural abundance of approximately 7%.cite journal| last = Audi | first = G.| title = Nubase2003 Evaluation of Nuclear and Decay Properties| journal = Nuclear Physics A| volume = 729| pages = 3–128| publisher = Atomic Mass Data Center| year = 2003| doi=10.1016/j.nuclphysa.2003.11.001] When bombarded with alpha particles, the isotope 72Ge will generate stable 77Se, releasing high energy electrons in the process. Because of this, it is used in combination with radon for nuclear batteries.cite web|url=http://www.nuenergy.org/disclosures/AlphaFusionPatent_05-04-2007.pdf |title=Alpha Fusion Electrical Energy Valve |format=pdf |accessdate=2008-09-10 | publisher = Nu Energy Research Institute]
At least 27
radioisotopes have also been synthesized ranging in atomic mass from 58 to 89. The most stable of these is 68Ge, decaying by electron capturewith a half-life of 270.95 d. The least stable is 60Ge with a half-life of 30 ms. While most of germanium's radioisotopes decay by beta decay, 61Ge and 64Ge decay by β+ delayed proton emission. 84Ge through 87Ge also have minor β- delayed neutron emissiondecay paths.
Germanium is created through
stellar nucleosynthesis, mostly by the s-processin asymptotic giant branchstars. The s-process is a slow neutroncapture of lighter elements inside pulsating red giantstars.cite journal | journal = The Astrophysical Journal Letters | volume = 578 | pages = L55–L58 | year = 2002 | doi = 10.1086/344473 | title = Discovery of Enhanced Germanium Abundances in Planetary Nebulae with the Far Ultraviolet Spectroscopic Explorer | first = N. C. | last = Sterling | coauthors = Dinerstein, Harriet L.; Bowers, Charles W.] Germanium has been detected in the atmosphere of Jupiter [cite journal| title= The tropospheric gas composition of Jupiter's north equatorial belt /NH3, PH3, CH3D, GeH4, H2O/ and the Jovian D/H isotopic ratio| last = Kunde| first = V. | coauthors = Hanel, R.; Maguire, W.; Gautier, D.; Baluteau, J. P.; Marten, A.; Chedin, A.; Husson, N.; Scott, N. |journal = Astrophysical J.| volume= 263|year= 1982|pages= 443–467|doi=10.1086/160516] and in some of the most distant stars. [cite journal| journal=Nature | volume=423|issue= 29|date=2003-05-01| doi=10.1038/423029a | title=Astronomy: Elements of surprise| last = Cowan | first = John| pages=29] Its abundance in the Earth's crust is approximately 1.6 ppm.cite journal| doi = 10.1016/j.oregeorev.2005.07.034 | title = Metallogenesis of germanium—A review | first = R. | last = Höll | coauthors = Kling, M.; Schroll, E.| journal = Ore Geology Reviews | volume = 30 | issues = 3–4 | year = 2007| pages = 145–180] There are only a few minerals like argyrodite, briartite, germanite, and renieritethat contain appreciable amounts of germanium, but no minable deposits exist for any of them. Nonetheless, none is mined for its germanium content. [cite web|url=http://www.resourceinvestor.com/pebble.asp?relid=31285|publisher=Resource Investor.com|accessdate=2008-09-09|title=Byproducts II: Another Germanium Rush? |first=Jack | last = Lifton|date=2007-04-26] Some zinc-copper-lead ore bodies contain enough germanium that it can be extracted from the final ore concentrate.
An unusual enrichment process causes a high content of germanium in some coal seams, which was discovered by
Victor Mordechai Goldschmidtduring a broad survey for germanium deposits.cite journal | journal = Nachrichten von der Gesellschaft der Wissenschaften zu Göttingen, Mathematisch-Physikalische Klasse | title = Ueber das Vorkommen des Germaniums in Steinkohlen und Steinkohlenprodukten | last = Goldschmidt| first = V. M. | pages = 141–167| year = 1930 | url =http://resolver.sub.uni-goettingen.de/purl?GDZPPN002508303] cite journal | journal = Nachrichten von der Gesellschaft der Wissenschaften zu Göttingen, Mathematisch-Physikalische Klasse | title = Zur Geochemie des Germaniums | last = Goldschmidt| first = V. M. | coauthors = Peters, Cl. | pages = 141–167 | url =http://resolver.sub.uni-goettingen.de/purl?GDZPPN002509180 | year = 1933] The highest concentration ever found was in the Hartley coal ash with up to 1.6% of germanium. The coal deposits near Xilinhaote Inner Mongoliacontains estimated 1600 tonnes of germanium.
Worldwide production in 2006 was roughly 100
tonnes of germanium. Currently, it is recovered as a by-product from sphaleriteores where it is concentrated in amounts of up to 0.3%, [cite journal|doi=10.1016/0016-7037(85)90241-8|title=Germanium geochemistry and mineralogy|year=1985|author=Bernstein, L|journal=Geochimica et Cosmochimica Acta|volume=49|pages=2409] especially from sediment-hosted, massive Zn–Pb–Cu(–Ba) deposits and carbonate-hosted Zn–Pb deposits. Figures for worldwide Ge reserves are not available, but in the US it is estimated to be around 500 tonnes. In 2007 35% of the demand was met by recycled germanium.
It is produced mainly from
sphalerite, a zincore, but is also found in silver, lead, and copperores. A source of germanium is fly ashof coal power plants which use coal from certain coal deposits with a large concentration of germanium. Russia and China used this as a source for germanium.cite journal | first = A. V. | last = Naumov | title = World market of germanium and its prospects | journal = Russian Journal of Non-Ferrous Metals | volume = 48 | issue = 4 | year = 2007 | doi = 10.3103/S1067821207040049 | pages =265–272] Russia's deposits are located in the far east of the country on Sakhalinisland. The coal mines northeast of Vladivostokhave also been used as a germanium source. The deposits in China are mainly located in the lignitemines near Lincang, Yunnanand coal mines near Xilinhaote, Inner Mongoliaand are also used as germanium sources.
: GeS2 + 3O2 → GeO2 + 2SO2
Part of the germanium ends up in the dust produced during this process, while the rest is converted to germanates which are leached together with the zinc from the cinder by sulfuric acid. After neutralisation only the zinc stays in solution and the precipitate contains the germanium and other metals. After reducing the amount of zinc in the precipitate by the Waelz process the residing Waelz oxide is leached a second time. The dioxide is obtained as precipitate and converted with
chlorinegas or hydrochloric acid to germanium tetrachloride, which has a low boiling point and can be distilled off:
: GeO2 + 4HCl → GeCl4 + 2H2O: GeO2 + 2Cl2 → GeCl4 + O2
Germanium tetrachloride is either hydrolysed to the oxide (GeO2) or purified by fractionated distillation and than hydrolysed.The highly pure GeO2 is now suitable for the production of germanium glass. The pure germanium oxide is reduced by the reaction with hydrogen to obtain germanium suitable for the infrared optics or semiconductor industry:
: GeO2 + 4H2 → Ge + 2H2O
The germanium for steel production and other industrial processes is normally reduced using carbon:cite journal | journal = Minerals Engineering | voulume = 17 | year = 2004 | pages = 393–402 | doi = 10.1016/j.mineng.2003.11.014 | title = Review of germanium processing worldwide | author = Moskalyk, R. R. | volume = 17]
: GeO2 + C → Ge + CO2
The major end uses for germanium in 2007, worldwide, were estimated to be: 35% for
fiber-opticsystems, 30% infrared optics, 15% for polymerizationcatalysts, and 15% for electronics and solar electric applications. The remaining 5% went into other uses such as phosphors, metallurgy, and chemotherapy.
The most notable physical characteristics of germania (GeO2) are its high index of refraction and its low optical dispersion. These make it especially useful for
wide-angle camera lenses, microscopy, and for the core part of optical fibers. [cite journal|title=Infrared Detector Arrays for Astronomy|journal=Annu. Rev. Astro. Astrophys. | year = 2007 |doi = 10.1146/annurev.astro.44.051905.092436 |last = Rieke | first = G.H.| volume = 45 | pages = 77] cite web| url =http://minerals.usgs.gov/minerals/pubs/commodity/germanium/220400.pdf | title = Germanium| first = Robert D. | last = Brown, Jr.| publisher = U.S. Geological Survey |format=pdf | year = 2000 | accessdate = 2008-09-22] It also replaced titania as the silica dopant for silica fiber, eliminating the need for subsequent heat treatment, which made the fibers brittle. [cite web | url = http://www.sri.com/policy/csted/reports/sandt/techin2/chp3.html | title = Chapter III: Optical Fiber For Communications | publisher = Stanford Research Institute | accessdate = 2008-08-22 ] At the end of 2002 the fiber optics industry accounted for 60% of the annual germanium use in the United States, but this use accounts for less than 10% of world wide consumption. GeSbTeis a phase changealloy used for its optic properties, such as in rewritable DVDs. [cite web|url=http://www.osta.org/technology/pdf/dvdqa.pdf |title=Understanding Recordable & Rewritable DVD First Edition |format=pdf |accessdate=2008-09-22| publisher = Optical Storage Technology Association (OSTA)]
Because germanium is transparent in the infrared it is a very important
infraredoptical material, that can be readily cut and polished into lenses and windows. It is especially used as the front optic in thermal imaging cameras working in the 8 to 14 micron wavelengthrange for passive thermal imaging and for hot-spot detection in military, night visionsystem in cars, and fire fighting applications. It is therefore used in infrared spectroscopes and other optical equipment which require extremely sensitive infrared detectors.
The alloy silicon germanide (commonly referred to as "
silicon-germanium", or SiGe) is rapidly becoming an important semiconductor material, for use in high speed integrated circuits. Circuits utilizing the properties of Si-SiGe junctions can be much faster than those using silicon alone. [cite journal|doi=10.1109/TED.2003.810484|title=SiGe HBT and BiCMOS technologies for optical transmission and wireless communication systems|year=2003 |last=Washio | first= K.|journal=IEEE Transactions on Electron Devices|volume=50|pages=656] Silicon-germanide is beginning to replace gallium arsenide(GaAs) in wireless communications devices. The SiGe chips, with high-speed properties, can be made with low-cost, well-established production techniques of the silicon chipindustry.
The recent rise in energy cost has improved the economics of
solar panels, a potential major new use of germanium. Germanium is the substrate of the wafers for high-efficiency multijunction photovoltaic cells for space applications. Because germanium and gallium arsenidehave very similar lattice constants, germanium substrates can be used to make gallium arsenide solar cells. [cite journal|doi=10.1002/pip.446|title=Space and terrestrial photovoltaics: synergy and diversity|year=2002|last=Bailey| first= Sheila G.|journal=Progress in Photovoltaics Research and Applications|volume=10|pages=399] The Mars Exploration Rovers and several satellites use triple junction gallium arsenide on germanium cells. [cite journal | doi = 10.1016/S0094-5765(02)00287-4| title = The performance of gallium arsenide/germanium solar cells at the Martian surface | year = 2004 | first = D. | last = Crisp | coauthors = Pathare, A.; Ewell, R. C.| journal = Progress in Photovoltaics Research and Applications | volume = 54 | issue = 2 | pages = 83–101 ]
Germanium-on-insulator substrates are seen as a potential replacement for silicon on miniaturized chips. Other uses in electronics include
phosphors in fluorescent lamps, and germanium-base solid-state light-emitting diodes (LEDs). Germanium transistors are still used in some effects pedals by musicians who wish to reproduce the distinctive tonal character of the "fuzz"-tone from the early rock and rollera, most notably the Dallas Arbiter Fuzz Face. [cite journal | author = Szweda, Roy | year = 2005 | title = Germanium phoenix | journal = III-Vs Review | volume = 18 | issue = 7 | pages = 55 | doi = 10.1016/S0961-1290(05)71310-7 ]
Germanium dioxide is also used in
catalysts for polymerisationin the production of polyethylene terephthalate(PET).cite journal | last = Thiele | first = Ulrich K. | year = 2001 | title = The Current Status of Catalysis and Catalyst Development for the Industrial Process of Poly(ethylene terephthalate) Polycondensation | journal = International Journal of Polymeric Materials | volume = 50 | issue = 3 | pages = 387 – 394 |doi = 10.1080/00914030108035115 ] The high brilliance of the produced polyester is especially used for PET bottles marketed in Japan. However, in the United States, no germanium is used for polymerization catalysts. Due to the similarity between silica (SiO2) and germanium dioxide (GeO2), the silica stationary phase in some gas chromatographycolumns can be replaced by GeO2. [cite journal | title = Germania-Based, Sol-Gel Hybrid Organic-Inorganic Coatings for Capillary Microextraction and Gas Chromatography | last= Fang| first=Li | coauthors =Kulkarni, Sameer; Alhooshani, Khalid; Malik, Abdul | journal = Anal. Chem. | volume = 79 | issue = 24 | pages = 9441–9451 | year = 2007 | doi = 10.1021/ac071056f ]
In recent years germanium has seen increasing use in precious metal alloys. In
sterling silveralloys, for instance, it has been found to reduce firescale, increase tarnish resistance, and increase the alloy's response to precipitation hardening. A tarnish-proof sterling silver alloy, trademarked Argentium, requires 1.2% germanium. The material has a very high refractive index(4.0) and so needs to be anti-reflection coated. Particularly, a very hard special antireflection coating of diamond-like carbon(DLC), refractive index 2.0, is a good match and produces a diamond-hard surface that can withstand much environmental rough treatment. [cite journal | first = Alan H. | last =Lettington | doi = 10.1016/S0008-6223(98)00062-1 | title = Applications of diamond-like carbon thin films | volume = 36 | issue = 5–6 | year = 1998 | pages =555–560 | journal = Carbon ] [cite journal | first = Michael N. | last = Gardos | coauthors = Bonnie L. Soriano, Steven H. Propst | title = Study on correlating rain erosion resistance with sliding abrasion resistance of DLC on germanium | journal = Proc. SPIE, | volume = 1325 | pages = 99 | year = 1990 | doi = 10.1117/12.22449 | issue = Mechanical Properties]
High purity germanium single crystal detectors can precisely identify radiation sources—for example in airport security. [cite web | title = Performance of Light-Weight, Battery-Operated, High Purity Germanium Detectors for Field Use | first = Ronald | last = Keyser | coauthor = Twomey, Timothy; Upp, Daniel | url = http://www.ortec-online.com/papers/inmm_2003_keyser.pdf |format=pdf| accessdate = 2008-09-06 | publisher = Oak Ridge Technical Enterprise Corporation (ORTEC)] Germanium is useful for monochromators for
beamlines used in single crystal neutron scatteringand synchrotron X-ray diffraction. The reflectivity has advantages over silicon in neutron and high energy X-ray applications. [cite journal |doi=10.1142/S0218301396000062 |year=1996 |author=Ahmed, F. U. |journal=International Journal of Modern Physics E |volume=5 |pages=131|title = Optimization of Germanium for Neutron Diffractometers] Crystals of high purity germanium are used in detectors for gamma spectroscopyand the search for dark matter. [citejournal |doi=10.1016/j.nuclphysa.2005.02.155 |title=Astrophysical constraints from gamma-ray spectroscopy |year=2006 |last=Diehl|first= R. |journal=Nuclear Physics A |volume=777 |pages=70 ]
Certain compounds of germanium have low toxicity to
mammals, but have toxic effects against certain bacteria.cite book| last = Emsley| first = John| title = Nature's Building Blocks| publisher = Oxford University Press| year = 2001| location = Oxford| pages = 506–510| isbn = 0-19-850341-5 ] This property makes these compounds useful as chemotherapeuticagents. [cite journal | first = Milan | last = Slavik | coauthors = Blanc, Oscar; Davis, Joan | title = Spirogermanium: A new investigational drug of novel structure and lack of bone marrow toxicity | journal = Investigational New Drugs | volume = 1 | issue = 3 | year = 1983 | doi = 10.1007/BF00208894 | pages = 225–234]
As early as 1922, doctors in the United States used the inorganic form of germanium to treat patients with
anemia. [cite report|url=http://minerals.usgs.gov/minerals/pubs/commodity/germanium/220798.pdf|format=pdf|publisher=US Geologial Surveys|accessdate=2008-09-09| title = Comodity Survey:Germanium | first = Robert D. | last = Brown Jr.] It was used in other forms of treatments, but its efficiency has been dubious. Its role in cancer treatments has been debated. [cite web | url = http://www.cancer.org/docroot/ETO/content/ETO_5_3X_Germanium.asp | title = Germanium | publisher = American Cancer Society| accessdate = 2008-08-31 ] FDAresearch has concluded that germanium, when used as a nutritional supplement, "presents potential human health hazard".cite journal | last = Tao | first = S. H. | coauthors = Bolger, P. M. | year = 1997 | month = June | title = Hazard Assessment of Germanium Supplements | journal = Regulatory Toxicology and Pharmacology | volume = 25 | issue = 3 | pages = 211–219 | doi = 10.1006/rtph.1997.1098 ]
Germanium is not thought to be essential to the health of plants or animals. Some of its compounds present a hazard to human health, however. For example, germanium chloride and germane (GeH4) are a liquid and gas, respectively, that can be very irritating to the eyes, skin, lungs, and throat. [cite journal | first = G.B. | last = Gerber | coauthors = Léonard, A.| year = 1997 | title = Mutagenicity, carcinogenicity and teratogenicity of germanium compounds | journal = Regulatory Toxicology and Pharmacology | volume = 387 | pages = 141–146 | doi = 10.1016/S1383-5742(97)00034-3 ] Germanium has little or no effect upon the environment because it usually occurs only as a trace element in ores and
carbonaceousmaterials and is used in very small quantities in commercial applications.
- Note_label|A|a|noneFrom Greek, "argyrodite" means "silver-containing". [cite report|url=http://www.handbookofmineralogy.org/pdfs/argyrodite.pdf|publisher="Mineral Data Publishing"| format=pdf|title=Argyrodite—chem|Ag|8|GeS|6|accessdate=2008-09-01]
- Note_label|B|b|none Just as the existence of the new element was predicted, the existence of the planet Neptune was predicted around 1843 by the mathematicians
John Couch Adamsand Urbain Leverrierfor the fact that Uranus was being pulled slightly out of position in its orbit. [cite journal | first=J. C. | last=Adams | url=http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1846MNRAS...7..149A&db_key=AST&data_type=HTML&format=&high=42c888df4622238 | title=Explanation of the observed irregularities in the motion of Uranus, on the hypothesis of disturbance by a more distant planet | journal=Monthly Notices of the Royal Astronomical Society | volume=7 | pages=149 | date=November 13, 1846 | accessdate=2008-02-18 | publisher=Blackwell Publishing] James Challisstarted searching for it in July 1846 and sighted the planet 23 September 1846. [cite journal | first=Rev. J. | last=Challis | url=http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=1846MNRAS...7..145C&db_key=AST&data_type=HTML&format=&high=42c888df4622238 | title=Account of observations at the Cambridge observatory for detecting the planet exterior to Uranus | journal=Monthly Notices of the Royal Astronomical Society | volume=7 | pages=145–149 | date=November 13, 1846 | accessdate=2008-02-18 | publisher=Blackwell Publishing]
- note_label|C|c|none R. Hermann published in 1877 claims of the discovery of a new element beneath
tantalum, which he named "neptunium". [cite journal| title=Scientific Miscellany| journal= The Galaxy |volume= 24| issue= 1| month= July |year= 1877|pages= 131| isbn=0665501668| first =Robert | last = Sears | publisher=Siebert & Lilley| location=Columbus, O [hio] | oclc=16890343 243523661 77121148] [cite journal | title=Editor's Scientific Record| journal=Harper's new monthly magazine| volume= 55 | issue=325|month = June| year=1877 |pages= 152–153 |url = http://cdl.library.cornell.edu/cgi-bin/moa/moa-cgi?notisid=ABK4014-0055-21] But this was later regarded as some mixture of niobiumand tantalum. [cite web| title = Elementymology & Elements Multidict: Niobium| first = Peter | last =van der Krogt | url = http://elements.vanderkrogt.net/elem/nb.html| accessdate = 2008-08-20] The name neptuniumwas eventually given to the synthetic element past uraniumdiscovered in 1940. [cite book |title=Nobel Lectures, Chemistry 1942-1962 |publisher=Elsevier |year=1964 |chapter=The Nobel Prize in Chemistry 1951: presentation speech| first =A. | last =Westgren | url =http://nobelprize.org/nobel_prizes/chemistry/laureates/1951/press.html]
* [http://www.webelements.com/webelements/elements/text/Ge/index.html WebElements.com – Germanium]
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Germanium — Gallium ← Germanium → Arsenic Si … Wikipédia en Français
GERMANIUM — De Germania , Allemagne Symbole chimique: Ge Numéro atomique: 32 Masse atomique: 72,59 Point de fusion: 937,4 0C Point d’ébullition: 2 830 0C Densité (à 20 0C): 5,32. Semi métal argenté qui a été découvert par Clemens Winkler dans l’argyrodite… … Encyclopédie Universelle
Germanium — (Ge, Atomgew. 72,3, spez. Gew. 5,5), sehr seltenes, 1886 von Cl. Winkler in einem bei Freiberg gefundenen Minerale Argyrodit GeS2(Ag2S)3 entdecktes grauweißes, sprödes Metall. Schmelzpunkt 900°; an der Luft beständig, bei Glühhitze unter Bildung… … Lexikon der gesamten Technik
Germanium — Ger*ma ni*um, n. [NL., fr. L. Germania Germany.] (Chem.) A rare element, discovered in 1885 in a silver ore (argyrodite) at Freiberg. It is a brittle, silver white metal, chemically intermediate between the metals and nonmetals, resembles tin,… … The Collaborative International Dictionary of English
Germanĭum — Ge, Metall, findet sich mit Schwefel und Schwefelsilber verbunden im Argyrodit, auch im Canfieldit, im Samarskit, Euxenit, in Spuren im Tantalit, Fergusonit, Niobit, Gadolinit etc. Es ist grauweiß, kristallisiert regulär, ist sehr spröde,… … Meyers Großes Konversations-Lexikon
Germanium — Germanĭum (chem. Zeichen Ge), sehr seltenes, dem Zinn ähnliches Metall; Atomgewicht 71,93, spez. Gewicht 5,5. Grauweiße, spröde Kristalle, von Winkler 1886 im Argyrodit entdeckt. Existenz und Eigenschaften von Mendelejew nach dem periodischen… … Kleines Konversations-Lexikon
germanium — GERMÁNIUM s.n. v. germaniu. Trimis de LauraGellner, 13.09.2007. Sursa: DN … Dicționar Român
germanium — Symbol: Ge Atomic number: 32 Atomic weight: 72.59 Lustrous hard metalloid element, belongs to group 14 of the periodic table. Forms a large number of organometallic compounds. Predicted by Mendeleev in 1871, it was actually found in 1886 by… … Elements of periodic system
germanium — [jər mā′nē əm] n. [ModL < L Germania, Germany] a grayish white, nonmetallic chemical element of the carbon family used in semiconductors, transistors, infrared equipment, etc.: symbol, Ge; at. no., 32: see the periodic table of elements in the … English World dictionary
Germanium — Eigenschaften … Deutsch Wikipedia