- Germanium dioxide
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IUPACName = germanium dioxide
OtherNames = Germanium oxide, Germanium(IV) oxide, Germania, Germanic oxide (crystalline), Germanic acid, ACC10380, G-15
Section1 = Chembox Identifiers
CASNo = 1310-53-8
PubChem = 14796
SMILES = O= [Ge] =O
InChI = 1/GeO2/c2-1-3
Section2 = Chembox Properties
Formula = GeO2
MolarMass = 104.61 g/mol
Appearance = white powder or colourless crystals
Density = 3.64 g/cm3
MeltingPt = 1115 °C
BoilingPt = 1200 °C
Solubility =5.2 g/l (25 °C)10.7 g/l (100 °C)
Section3 = Chembox Hazards
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RPhrases = R22Germanium dioxide, also called germanium oxide and germania, is an
inorganic compound , anoxide ofgermanium . Its chemical formula is GeO2. Its other names are germanic acid, G-15, and ACC10380. It forms as apassivation layer on pure germanium in contact with atmospheric oxygen.tructure
The forms of germanium dioxide to an extent parallel those of silicon dioxide, hexagonal GeO2 has the same structure as β-quartz (coordination number of germanium 4), tetragonal GeO2 (the mineral
argutite ) has therutile like structure ofstishovite ,(coordination number of germanium 6) and amorphous GeO2 is similar tofused silica . Greenwood&Earnshaw] It can be prepared bothcrystalline andamorphous . At very high pressures,amorphous (glassy) germanium dioxide forms changes coordination to 6 coordinate, when the pressure is reduced the structure reverts back to the 4 coordinate form. [Formation and Structure of a Dense Octahedral Glass, M. Guthrie, C. A. Tulk, C. J. Benmore, J. Xu, J. L. Yarger, D. D. Klug, J. S. Tse, H-k. Mao, R. J. Hemley, Physical Review Letters, 93, 115502, doi|10.1103/PhysRevLett.93.115502] At high pressure the rutile form converts to an orthorhombic CaCl2 form [Structural evolution of rutile-type and CaCl2-type germanium dioxide at high pressure, J. Haines, J. M.Léger, C.Chateau, A. S.Pereira, Physics and Chemistry of Minerals, 27, 8 ,(2000), 575-582,doi|10.1007/s002690000092]Reactions
Heating germanium dioxide with powdered
germanium at 1000 °C formsgermanium monoxide (GeO).
The rutile form of germanium dioxide is more soluble than the hexagonal form and dissolves to formgermanic acid , H4GeO4 which may be Ge(OH)4.Egon Wiberg, Arnold Frederick Holleman, (2001) "Inorganic Chemistry", Elsevier ISBN 0123526515] GeO2 is only slightly soluble in acid but dissolves more readily in alkali to give germanates.
It is not flammable. In contact withhydrochloric acid it releases volatile and corrosivegermanium tetrachloride .Uses
Germanium dioxide's
refractive index (1.7) and optical dispersion properties make it useful as an optical material forwide-angle lens es and inoptical microscope objective lenses. It is transparent ininfrared .
A mixture of silicon dioxide and germanium dioxide ("silica-germania") is used as an optical material foroptical fiber s andoptical waveguide s.cite web| url =http://minerals.usgs.gov/minerals/pubs/commodity/germanium/220400.pdf | title = GERMANIUM| author = Robert D. Brown, Jr.| publisher = U.S. Geological Survey | year = 2000] Controlling the ratio of the elements allows precise control of refractive index. Silica-germania glasses have lower viscosity and higher refractive index than pure silica. Germania replaced titania as the silica dopant for silica fiber, eliminating the need for subsequent heat treatment, which made the fibers brittle. [ [http://www.sri.com/policy/csted/reports/sandt/techin2/chp3.html Chapter Iii: Optical Fiber For Communications ] ]Germanium dioxide is also used as a
catalyst in production ofpolyethylene terephthalate resin,cite journal | author = Thiele, 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 ] and for production of other germanium compounds. It is used as a feedstock for production of somephosphor s andsemiconductor material s.In the manufacture of integrated circuits and transistors, germanium dioxide is a rather poor dielectric and is chemically unstable, which is one of the disadvantages of germanium in comparison with silicon.Toxicity and medical
Germanium dioxide has low toxicity; in higher doses it is
nephrotoxic . Germanium dioxide is used as a germanium supplement in some questionabledietary supplement s and "miracle cures". [cite journal | author = Tao, S.H. and 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 ] High doses of these resulted in several cases of germanium poisonings.References
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