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This article is about the chemical element. For other uses, see Tungsten (disambiguation).
Tungsten, 74W
Tungsten
Pronunciation/ˈtʌŋstən/ ​(TUNG-stən)
Alternative nameWolfram, pronounced: /ˈwʊlfrəm/ (WUUL-frəm)
Allotropesα-tungsten (common), β-tungsten
AppearanceGrayish white, lustrous
Standard atomic weight Ar°(W)
Tungsten in the periodic table
Hydrogen Helium
Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon
Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon
Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton
Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon
Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon
Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson
Mo
↑
W
↓
Sg
tantalum ← tungsten → rhenium
Atomic number (Z)74
Groupgroup 6
Periodperiod 6
Block  d-block
Electron configuration[Xe] 4f14 5d4 6s2[3]
Electrons per shell2, 8, 18, 32, 12, 2
Physical properties
Phase at STPsolid
Melting point3695 K ​(3422 °C, ​6192 °F)
Boiling point6203 K ​(5930 °C, ​10706 °F)
Density (at 20° C)19.254 g/cm3 [4]
when liquid (at m.p.)17.6 g/cm3
Heat of fusion52.31 kJ/mol[5][6]
Heat of vaporization774 kJ/mol
Molar heat capacity24.27 J/(mol·K)
Vapor pressure
P (Pa) 1 10 100 1 k 10 k 100 k
at T (K) 3477 3773 4137 4579 5127 5823
Atomic properties
Oxidation statescommon: +4, +6
−4,? −2,[7] −1,[7] 0,? +1,[7] +2,[7] +3,[7] +5[7]
ElectronegativityPauling scale: 2.36
Ionization energies
  • 1st: 770 kJ/mol
  • 2nd: 1700 kJ/mol
Atomic radiusempirical: 139 pm
Covalent radius162±7 pm
Color lines in a spectral range
Spectral lines of tungsten
Other properties
Natural occurrenceprimordial
Crystal structure ​body-centered cubic (bcc) (cI2)
Lattice constant
Body-centered cubic crystal structure for tungsten
a = 316.52 pm (at 20 °C)[4]
Thermal expansion4.42×10−6/K (at 20 °C)[4]
Thermal conductivity173 W/(m⋅K)
Electrical resistivity52.8 nΩ⋅m (at 20 °C)
Magnetic orderingparamagnetic[8]
Molar magnetic susceptibility+59.0×10−6 cm3/mol (298 K)[9]
Young's modulus411 GPa
Shear modulus161 GPa
Bulk modulus310 GPa
Speed of sound thin rod4620 m/s (at r.t.) (annealed)
Poisson ratio0.28
Mohs hardness7.5
Vickers hardness3430–4600 MPa
Brinell hardness2000–4000 MPa
CAS Number7440-33-7
History
Discovery and first isolationJuan José Elhuyar and Fausto Elhuyar[10] (1783)
Named byTorbern Bergman (1781)
Symbol"W": from Wolfram, originally from Middle High German wolf-rahm 'wolf's foam' describing the mineral wolframite[11]
Isotopes of tungsten
Main isotopes Decay
abun­dance half-life (t1/2) mode pro­duct
180W 0.120% 1.8×1018 y α 176Hf
181W synth 121.2 d ε 181Ta
182W 26.5% stable
183W 14.3% stable
184W 30.6% stable
185W synth 75.1 d β− 185Re
186W 28.4% stable
188W synth 69.78 d β− 188Re
 Category: Tungsten
| references

Tungsten, also known as wolfram, is a chemical element with the chemical symbol W and atomic number 74. The word tungsten comes from the Swedish language tung sten directly translatable to heavy stone,[12] though the name is volfram in Swedish to distinguish it from Scheelite, which in Swedish is alternatively named tungsten.

A hard, rare metal under standard conditions when uncombined, tungsten is found naturally on Earth only in chemical compounds. It was identified as a new element in 1781, and first isolated as a metal in 1783. Its important ores include wolframite and scheelite. The free element is remarkable for its robustness, especially the fact that it has the highest melting point of all the elements. Also remarkable is its high density of 19.3 times that of water, comparable to that of uranium and gold, and much higher (about 1.7 times) than that of lead.[13] Tungsten with minor amounts of impurities is often brittle[14] and hard, making it difficult to work. However, very pure tungsten, though still hard, is more ductile, and can be cut with a hard-steel hacksaw.[15]

Tungsten's many alloys have numerous applications, most notably in incandescent light bulb filaments, X-ray tubes (as both the filament and target), electrodes in TIG welding, superalloys, and radiation shielding. About half is used in the form of tungsten carbide, a durable carbon alloy. Tungsten's hardness and high density give it military applications in penetrating projectiles. Tungsten compounds are also often used as industrial catalysts.

Tungsten is the only metal from the third transition series that is known to occur in biomolecules, where it is used in a few species of bacteria and archaea. It is the heaviest element known to be used by any living organism. Tungsten interferes with molybdenum and copper metabolism, and is somewhat toxic to animal life.[16][17]

Characteristics

Physical properties

In its raw form, tungsten is a hard steel-grey metal that is often brittle and hard to work. If made very pure, tungsten retains its hardness (which exceeds that of many steels), and becomes malleable enough that it can be worked easily.[15] It is worked by forging, drawing, or extruding. Tungsten objects are also commonly formed by sintering.

Of all metals in pure form, tungsten has the highest melting point (3,422 °C, 6,192 °F), lowest vapor pressure (at temperatures above 1,650 °C, 3,000 °F) and the highest tensile strength.[18] Although carbon remains solid at higher temperatures than tungsten, carbon sublimes, rather than melts, so tungsten is considered to have a higher melting point. Tungsten has the lowest coefficient of thermal expansion of any pure metal. The low thermal expansion and high melting point and tensile strength of tungsten originate from strong covalent bonds formed between tungsten atoms by the 5d electrons.[19] Alloying small quantities of tungsten with steel greatly increases its toughness.[13]

Tungsten exists in two major crystalline forms: α and β. The former has a body-centered cubic structure and is the most stable form. The structure of the β phase is called A15 cubic; it is metastable, but can coexist with the α phase at ambient conditions owing to non-equilibrium synthesis or stabilization by impurities. Contrary to the α phase which crystallizes in isometric grains, the β form exhibits a columnar habit. The α phase has a three times lower electrical resistivity[20] and a much lower superconducting transition temperature TC than the β phase: ca. 0.015 K vs. 1–4 K; mixing the two phases allows obtaining intermediate TC values.[21][22] The TC value can also be raised by alloying tungsten with another metal (e.g. 7.9 K for W-Tc).[23] Such tungsten alloys are sometimes used in low-temperature superconducting circuits.[24][25][26]

Isotopes

Main article: Isotopes of tungsten

Naturally occurring tungsten consists of five isotopes whose half-lives are so long that they can be considered stable. Theoretically, all five can decay into isotopes of element 72 (hafnium) by alpha emission, but only 180W has been observed[27] to do so with a half-life of (1.8 ± 0.2)×1018 years; on average, this yields about two alpha decays of 180W in one gram of natural tungsten per year.[28] The other naturally occurring isotopes have not been observed to decay, constraining their half-lives to be:

182W, T1/2 > 1.7×1020 years
183W, T1/2 > 8×1019 years
184W, T1/2 > 1.8×1020 years
186W, T1/2 > 4.1×1018 years

Another 30 artificial radioisotopes of tungsten have been characterized, the most stable of which are 181W with a half-life of 121.2 days, 185W with a half-life of 75.1 days, 188W with a half-life of 69.4 days, 178W with a half-life of 21.6 days, and 187W with a half-life of 23.72 h.[28] All of the remaining radioactive isotopes have half-lives of less than 3 hours, and most of these have half-lives below 8 minutes.[28] Tungsten also has 4 meta states, the most stable being 179mW (T½ 6.4 minutes).

Chemical properties

Main article: Tungsten compounds

Elemental tungsten resists attack by oxygen, acids, and alkalis.[29]

The most common formal oxidation state of tungsten is +6, but it exhibits all oxidation states from −2 to +6.[29][30] Tungsten typically combines with oxygen to form the yellow tungstic oxide, WO3, which dissolves in aqueous alkaline solutions to form tungstate ions, WO2−
4.

Tungsten carbides (W2C and WC) are produced by heating powdered tungsten with carbon. W2C is resistant to chemical attack, although it reacts strongly with chlorine to form tungsten hexachloride (WCl6).[13]

In aqueous solution, tungstate gives the heteropoly acids and polyoxometalate anions under neutral and acidic conditions. As tungstate is progressively treated with acid, it first yields the soluble, metastable "paratungstate A" anion, W
7O6–
24, which over time converts to the less soluble "paratungstate B" anion, H
2W
12O10–
42.[31] Further acidification produces the very soluble metatungstate anion, H
2W
12O6–
40, after which equilibrium is reached. The metatungstate ion exists as a symmetric cluster of twelve tungsten-oxygen octahedra known as the Keggin anion. Many other polyoxometalate anions exist as metastable species. The inclusion of a different atom such as phosphorus in place of the two central hydrogens in metatungstate produces a wide variety of heteropoly acids, such as phosphotungstic acid H3PW12O40.

Tungsten trioxide can form intercalation compounds with alkali metals. These are known as bronzes; an example is sodium tungsten bronze.

Occurrence

Tungsten is found in the minerals wolframite (iron-manganese tungstate, (Fe,Mn)WO4), scheelite (calcium tungstate, (CaWO4), ferberite (FeWO4) and hübnerite (MnWO4). China produced 51,000 tonnes of tungsten concentrate in 2009, which was 83% of the world output. In the prelude to WWII China's production of tungsten played a role as China could use this leverage to demand material assistance from the US government.[32] Most of the remaining production originated from Russia (2,500 t), Canada (1,964 t), Bolivia (1,023 t), Austria (900 t), Portugal (900 t), Thailand (600 t), Brazil (500 t), Peru (500 t) and Rwanda (500 t).[33] Tungsten is also considered to be a conflict mineral due to the unethical mining practices observed in the Democratic Republic of the Congo.[34][35] Rising prices in 2014 have enabled works to reopen the disused Hemerdon Bal tungsten-tin mine in Plymouth in the United Kingdom.[36]

Biological role

Tungsten, at atomic number 74, is the heaviest element known to be biologically functional, with the next heaviest being iodine (Z = 53). It is used by some bacteria, but not in eukaryotes. For example, enzymes called oxidoreductases use tungsten similarly to molybdenum by using it in a tungsten-pterin complex with molybdopterin (molybdopterin, despite its name, does not contain molybdenum, but may complex with either molybdenum or tungsten in use by living organisms). Tungsten-using enzymes typically reduce carboxylic acids to aldehydes.[37] The tungsten oxidoreductases may also catalyse oxidations. The first tungsten-requiring enzyme to be discovered also requires selenium, and in this case the tungsten-selenium pair may function analogously to the molybdenum-sulfur pairing of some molybdenum cofactor-requiring enzymes.[38] One of the enzymes in the oxidoreductase family which sometimes employ tungsten (bacterial formate dehydrogenase H) is known to use a selenium-molybdenum version of molybdopterin.[39] Although a tungsten-containing xanthine dehydrogenase from bacteria has been found to contain tungsten-molydopterin and also non-protein bound selenium, a tungsten-selenium molybdopterin complex has not been definitively described.[40]

In soil, tungsten metal oxidizes to the tungstate anion. It can be selectively or non-selectively imported by some prokaryotic organisms and may substitute for molybdate in certain enzymes. Its effect on the action of these enzymes is in some cases inhibitory and in others positive.[41] The soil's chemistry determines how the tungsten polymerizes; alkaline soils cause monomeric tungstates; acidic soils cause polymeric tungstates.[42]

Sodium tungstate and lead have been studied for their effect on earthworms. Lead was found to be lethal at low levels and sodium tungstate was much less toxic, but the tungstate completely inhibited their reproductive ability.[43]

Tungsten has been studied as a biological copper metabolic antagonist, in a role similar to the action of molybdenum. It has been found that tetrathiotungstates may be used as biological copper chelation chemicals, similar to the tetrathiomolybdates.[44]

History

In 1781, Carl Wilhelm Scheele discovered that a new acid, tungstic acid, could be made from scheelite (at the time named tungsten). Scheele and Torbern Bergman suggested that it might be possible to obtain a new metal by reducing this acid.[45] In 1783, José and Fausto Elhuyar found an acid made from wolframite that was identical to tungstic acid. Later that year, in Spain, the brothers succeeded in isolating tungsten by reduction of this acid with charcoal, and they are credited with the discovery of the element.[46][47]

In World War II, tungsten played a significant role in background political dealings. Portugal, as the main European source of the element, was put under pressure from both sides, because of its deposits of wolframite ore at Panasqueira. Tungsten's resistance to high temperatures and its strengthening of alloys made it an important raw material for the arms industry.[48][49]

Etymology

The name "tungsten" (from the Swedish tung sten, "heavy stone") is used in English, French, and many other languages as the name of the element, but not in the Nordic countries. Tungsten was the old Swedish name for the mineral scheelite. The other name "wolfram" (or "volfram"), is used in most European (especially Germanic and Slavic) languages, and is derived from the mineral wolframite, which is the origin of its chemical symbol, W.[15] The name "wolframite" is derived from German "wolf rahm" ("wolf soot" or "wolf cream"), the name given to tungsten by Johan Gottschalk Wallerius in 1747. This, in turn, derives from "Lupi spuma", the name Georg Agricola used for the element in 1546, which translates into English as "wolf's froth", and is a reference to the large amounts of tin consumed by the mineral during its extraction.[11]

Production

Wolframite, scale in cm
Tungsten output in 2005

About 61,300 tonnes of tungsten concentrates were produced in the year 2009.[33] Tungsten is extracted from its ores in several stages. The ore is eventually converted to tungsten(VI) oxide (WO3), which is heated with hydrogen or carbon to produce powdered tungsten.[45] Because of tungsten's high melting point, it is not commercially feasible to cast tungsten ingots. Instead, powdered tungsten is mixed with small amounts of powdered nickel or other metals, and sintered. During the sintering process, the nickel diffuses into the tungsten, producing an alloy.

Tungsten can also be extracted by hydrogen reduction of WF6:

WF6 + 3 H2 → W + 6 HF

or pyrolytic decomposition:[50]

WF6 → W + 3 F2 (ΔHr = +)

Tungsten is not traded as a futures contract and cannot be tracked on exchanges like the London Metal Exchange. The prices are usually quoted for tungsten concentrate or WO3. If converted to the metal equivalent, they were about US$19 per kilogram in 2009.[33]

Applications

Close-up of a tungsten filament inside a halogen lamp
Tungsten carbide ring (jewelry)

Approximately half of the tungsten is consumed for the production of hard materials – namely tungsten carbide – with the remaining major use being in alloys and steels. Less than 10% is used in other chemical compounds.[51]

Hard materials

Tungsten is mainly used in the production of hard materials based on tungsten carbide, one of the hardest carbides, with a melting point of 2770 °C. WC is an efficient electrical conductor, but W2C is less so. WC is used to make wear-resistant abrasives, and "carbide" cutting tools such as knives, drills, circular saws, milling and turning tools used by the metalworking, woodworking, mining, petroleum and construction industries.[13] Carbide tooling is actually a ceramic/metal composite, where metallic cobalt acts as a binding (matrix) material to hold the WC particles in place. This type of industrial use accounts for about 60% of current tungsten consumption.[52]

The jewelry industry makes rings of sintered tungsten carbide, tungsten carbide/metal composites, and also metallic tungsten.[53] WC/metal composite rings use nickel as the metal matrix in place of cobalt because it takes a higher luster when polished. Sometimes manufacturers or retailers refer to tungsten carbide as a metal, but it is a ceramic.[54] Because of tungsten carbide's hardness, rings made of this material are extremely abrasion resistant, and will hold a burnished finish longer than rings made of metallic tungsten.[55] Tungsten carbide rings are brittle, however, and may crack under a sharp blow.[56]

Alloys

The hardness and density of tungsten are applied in obtaining heavy metal alloys. A good example is high speed steel, which can contain as much as 18% tungsten.[57] Tungsten's high melting point makes tungsten a good material for applications like rocket nozzles, for example in the UGM-27 Polaris submarine-launched ballistic missile.[58] Tungsten alloys are used in a wide range of different applications, including the aerospace and automotive industries and radiation shielding.[59] Superalloys containing tungsten, such as Hastelloy and Stellite, are used in turbine blades and wear-resistant parts and coatings.

Armaments

Tungsten, usually alloyed with nickel and iron or cobalt to form heavy alloys, is used in kinetic energy penetrators as an alternative to depleted uranium, in applications where uranium's radioactivity is problematic even in depleted form, or where uranium's additional pyrophoric properties are not required (for example, in ordinary small arms bullets designed to penetrate body armor). Similarly, tungsten alloys have also been used in cannon shells, grenades and missiles, to create supersonic shrapnel. Tungsten has also been used in Dense Inert Metal Explosives, which use it as dense powder to reduce collateral damage while increasing the lethality of explosives within a small radius.[60]

Chemical applications

Tungsten(IV) sulfide is a high temperature lubricant and is a component of catalysts for hydrodesulfurization.[61] MoS2 is more commonly used for such applications.[62]

Tungsten oxides are used in ceramic glazes and calcium/magnesium tungstates are used widely in fluorescent lighting. Crystal tungstates are used as scintillation detectors in nuclear physics and nuclear medicine. Other salts that contain tungsten are used in the chemical and tanning industries.[18]

Tungsten oxide (WO3) is incorporated into selective catalytic reduction (SCR) catalysts found in coal-fired power plants. These catalysts convert nitrogen oxides (NOx) to nitrogen (N2) and water (H2O) using ammonia (NH3). The tungsten oxide helps with the physical strength of the catalyst and extends catalyst life.[63]

Niche uses

Applications requiring its high density include weights, counterweights, ballast keels for yachts, tail ballast for commercial aircraft, and as ballast in race cars for NASCAR and Formula One; depleted uranium is also used for these purposes, due to similarly high density. 75-kg blocks of tungsten were used as "cruise balance mass devices" on the entry vehicle portion of the 2012 Mars Science Laboratory spacecraft. It is an ideal material to use as a dolly for riveting, where the mass necessary for good results can be achieved in a compact bar. High-density alloys of tungsten with nickel, copper or iron are used in high-quality darts[64] (to allow for a smaller diameter and thus tighter groupings) or for fishing lures (tungsten beads allow the fly to sink rapidly). Some types of strings for musical instruments are wound with tungsten wires.

Sodium tungstate is used in Folin-Ciocalteu's reagent, a mixture of different chemicals used in the "Lowry Assay" for protein content analysis.

Gold substitution

Its density, similar to that of gold, allows tungsten to be used in jewelry as an alternative to gold or platinum.[15][65] Metallic tungsten is hypoallergenic, and is harder than gold alloys (though not as hard as tungsten carbide), making it useful for rings that will resist scratching, especially in designs with a brushed finish.

Because the density is so similar to that of gold (tungsten is only 0.36% less dense), tungsten can also be used in counterfeiting of gold bars, such as by plating a tungsten bar with gold,[66][67][68] which has been observed since the 1980s,[69] or taking an existing gold bar, drilling holes, and replacing the removed gold with tungsten rods.[70] The densities are not exactly the same, and other properties of gold and tungsten differ, but gold-plated tungsten will pass superficial tests.[66]

Gold-plated tungsten is available commercially from China (the main source of tungsten), both in jewelry and as bars.[71]

Electronics

Because it retains its strength at high temperatures and has a high melting point, elemental tungsten is used in many high-temperature applications,[72] such as light bulb, cathode-ray tube, and vacuum tube filaments, heating elements, and rocket engine nozzles.[15] Its high melting point also makes tungsten suitable for aerospace and high-temperature uses such as electrical, heating, and welding applications, notably in the gas tungsten arc welding process (also called tungsten inert gas (TIG) welding).

Tungsten electrode used in a Gas tungsten arc welding torch

Because of its conductive properties and relative chemical inertness, tungsten is also used in electrodes, and in the emitter tips in electron-beam instruments that use field emission guns, such as electron microscopes. In electronics, tungsten is used as an interconnect material in integrated circuits, between the silicon dioxide dielectric material and the transistors. It is used in metallic films, which replace the wiring used in conventional electronics with a coat of tungsten (or molybdenum) on silicon.[50]

The electronic structure of tungsten makes it one of the main sources for X-ray targets,[73][74] and also for shielding from high-energy radiations (such as in the radiopharmaceutical industry for shielding radioactive samples of FDG). It is also used in gamma imaging as a material from which coded apertures are made, due to its excellent shielding properties. Tungsten powder is used as a filler material in plastic composites, which are used as a nontoxic substitute for lead in bullets, shot, and radiation shields. Since this element's thermal expansion is similar to borosilicate glass, it is used for making glass-to-metal seals.[18]

Precautions

Because tungsten is rare and its compounds are generally inert, the effects of tungsten on the environment are limited.[75] The median lethal dose LD50 depends strongly on the animal and the method of administration and varies between 59 mg/kg (intravenous, rabbits)[76][77] and 5000 mg/kg (tungsten metal powder, intraperitoneal, rats).[78][79]

Patent claim

Tungsten is unique amongst the elements in that it has been the subject of patent proceedings. In 1928, a US court rejected General Electric's attempt to patent it, overturning U.S. patent 1,082,933 granted in 1913 to William D. Coolidge.[80][81]

See also

References

  1. ^ "Standard Atomic Weights: Tungsten". CIAAW. 1991.
  2. ^ Prohaska, Thomas; Irrgeher, Johanna; Benefield, Jacqueline; Böhlke, John K.; Chesson, Lesley A.; Coplen, Tyler B.; Ding, Tiping; Dunn, Philip J. H.; Gröning, Manfred; Holden, Norman E.; Meijer, Harro A. J. (2022-05-04). "Standard atomic weights of the elements 2021 (IUPAC Technical Report)". Pure and Applied Chemistry. doi:10.1515/pac-2019-0603. ISSN 1365-3075.
  3. ^ Berger, Dan. "Why does Tungsten not 'Kick' up an electron from the s sublevel ?". Bluffton College, USA.
  4. ^ a b c Arblaster, John W. (2018). Selected Values of the Crystallographic Properties of Elements. Materials Park, Ohio: ASM International. ISBN 978-1-62708-155-9.
  5. ^ Lide, David R., ed. (2009). CRC Handbook of Chemistry and Physics (90th ed.). Boca Raton, Florida: CRC Press. p. 6-134. ISBN 978-1-4200-9084-0.
  6. ^ Tolias P. (2017). "Analytical expressions for thermophysical properties of solid and liquid tungsten relevant for fusion applications". Nuclear Materials and Energy. 13: 42–57. arXiv:1703.06302. Bibcode:2017arXiv170306302T. doi:10.1016/j.nme.2017.08.002. S2CID 99610871.
  7. ^ a b c d e f Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 28. ISBN 978-0-08-037941-8.
  8. ^ Lide, D. R., ed. (2005). "Magnetic susceptibility of the elements and inorganic compounds" (PDF). CRC Handbook of Chemistry and Physics (86th ed.). Boca Raton (FL): CRC Press. ISBN 978-0-8493-0486-6. Archived from the original (PDF) on 2011-03-03.
  9. ^ Weast, Robert (1984). CRC, Handbook of Chemistry and Physics. Boca Raton, Florida: Chemical Rubber Company Publishing. p. E110. ISBN 978-0-8493-0464-4.
  10. ^ "Tungsten". Royal Society of Chemistry. Royal Society of Chemistry. Retrieved May 2, 2020.
  11. ^ a b van der Krogt, Peter. "Wolframium Wolfram Tungsten". Elementymology& Elements Multidict. Archived from the original on 2010-01-23. Retrieved 2010-03-11. Cite error: The named reference "sweetums" was defined multiple times with different content (see the help page).
  12. ^ "Tungsten". Oxford English Dictionary (Online ed.). Oxford University Press. (Subscription or participating institution membership required.)
  13. ^ a b c d Daintith, John (2005). Facts on File Dictionary of Chemistry (4th ed.). New York: Checkmark Books. ISBN 0-8160-5649-8.
  14. ^ Lassner, Erik; Schubert, Wolf-Dieter (1999). "low temperature brittleness". Tungsten: properties, chemistry, technology of the element, alloys, and chemical compounds. Springer. pp. 20–21. ISBN 978-0-306-45053-2.
  15. ^ a b c d e Stwertka, Albert (2002). A Guide to the elements (2nd ed.). New York: Oxford University Press. ISBN 0-19-515026-0.
  16. ^ McMaster, J. and Enemark, John H (1998). "The active sites of molybdenum- and tungsten-containing enzymes". Current Opinion in Chemical Biology. 2 (2): 201–207. doi:10.1016/S1367-5931(98)80061-6. PMID 9667924.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  17. ^ Hille, Russ (2002). "Molybdenum and tungsten in biology". Trends in Biochemical Sciences. 27 (7): 360–367. doi:10.1016/S0968-0004(02)02107-2. PMID 12114025.
  18. ^ a b c C. R. Hammond (2004). The Elements, in Handbook of Chemistry and Physics 81st edition. CRC press. ISBN 0-8493-0485-7.
  19. ^ Erik Lassner, Wolf-Dieter Schubert (1999). Tungsten: properties, chemistry, technology of the element, alloys, and chemical compounds. Springer. p. 9. ISBN 0-306-45053-4.
  20. ^ Heather Bean Material Properties and Analysis Techniques for Tungsten Thin Films. October 19, 1998
  21. ^ Lita, A. E.; Rosenberg, D.; Nam, S.; Miller, A.; Balzar, D.; Kaatz, L. M.; Schwall, R. E (2005). "Tuning of Tungsten Thin Film Superconducting Transition Temperature for Fabrication of Photon Number Resolving Detectors" (PDF). IEEE Transactions on Applied Superconductivity. 15 (2): 3528–3531. doi:10.1109/TASC.2005.849033.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  22. ^ Johnson, R. T.; O. E. Vilches; J. C. Wheatley; Suso Gygax (1966). "Superconductivity of Tungsten". Physical Review Letters. 16 (3): 101–104. Bibcode:1966PhRvL..16..101J. doi:10.1103/PhysRevLett.16.101.
  23. ^ Autler, S. H.; J. K. Hulm; R. S. Kemper (1965). "Superconducting Technetium-Tungsten Alloys". Physical Review. 140 (4A): A1177–A1180. Bibcode:1965PhRv..140.1177A. doi:10.1103/PhysRev.140.A1177.
  24. ^ Shailos, A; W Nativel; A Kasumov; C Collet; M Ferrier; S Guéron; R Deblock; H Bouchiat (2007). "Proximity effect and multiple Andreev reflections in few-layer graphene". Europhysics Letters (EPL). 79 (5): 57008. arXiv:cond-mat/0612058. Bibcode:2007EL.....7957008S. doi:10.1209/0295-5075/79/57008.
  25. ^ Kasumov, A. Yu. (2005). "Proximity effect in a superconductor-metallofullerene-superconductor molecular junction". Physical Review B. 72 (3): 033414. arXiv:cond-mat/0402312. Bibcode:2005PhRvB..72c3414K. doi:10.1103/PhysRevB.72.033414. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  26. ^ Kirk, M. D. (1987). "Point-contact electron tunneling into the high-T_{c} superconductor Y-Ba-Cu-O". Physical Review B. 35 (16): 8850–8852. Bibcode:1987PhRvB..35.8850K. doi:10.1103/PhysRevB.35.8850. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  27. ^ F. A. Danevich; et al. (2003). "α activity of natural tungsten isotopes". Phys. Rev. C. 67 (1): 014310. arXiv:nucl-ex/0211013. Bibcode:2003PhRvC..67a4310D. doi:10.1103/PhysRevC.67.014310. {{cite journal}}: Explicit use of et al. in: |author= (help)
    C. Cozzini; et al. (2004). "Detection of the natural α decay of tungsten". Phys. Rev. C. 70 (6): 064606. arXiv:nucl-ex/0408006. Bibcode:2004PhRvC..70f4606C. doi:10.1103/PhysRevC.70.064606. {{cite journal}}: Explicit use of et al. in: |author= (help)
  28. ^ a b c Alejandro Sonzogni. "Interactive Chart of Nuclides". National Nuclear Data Center: Brookhaven National Laboratory. Retrieved 2008-06-06.
  29. ^ a b Emsley, John E. (1991). The elements (2nd ed.). New York: Oxford University Press. ISBN 0-19-855569-5.
  30. ^ Morse, P. M.; Shelby, Q. D.; Kim, D. Y.; Girolami, G. S. (2008). "Ethylene Complexes of the Early Transition Metals: Crystal Structures of [HfEt4(C2H4)2−] and the Negative-Oxidation-State Species [TaHEt(C2H4)33−] and [WH(C2H4)43−]". Organometallics. 27 (5): 984–993. doi:10.1021/om701189e.
  31. ^ Smith, Bradley J.; Patrick, Vincent A. (2000). "Quantitative Determination of Sodium Metatungstate Speciation by 183W N.M.R. Spectroscopy". Australian Journal of Chemistry. 53 (12). CSIRO: 965. doi:10.1071/CH00140. Retrieved 2008-06-17.
  32. ^ Skolnick, Sherman H. (January 15, 2012). "RED CHINA and THE AMERICAN PRESIDENTIAL ELECTIONS". Skolnick's Report. Retrieved January 16, 2012.[dead link‍][unreliable source?]
  33. ^ a b c Shedd, Kim B. (2009). "Tungsten (table 15)" (PDF). United States Geological Survey. Retrieved 2011-06-18.
  34. ^ Kristof, Nicholas D. Death by Gadget. The New York Times. June 26, 2010
  35. ^ The Genocide Behind Your Smart Phone. The Daily Beast. July 16, 2010
  36. ^ http://www.bbc.co.uk/news/uk-england-devon-27754535
  37. ^ Lassner, Erik (1999). Tungsten: Properties, Chemistry, Technology of the Element, Alloys and Chemical Compounds. Springer. pp. 409–411. ISBN 0-306-45053-4.
  38. ^ Stiefel, E. I. (1998). "Transition metal sulfur chemistry and its relevance to molybdenum and tungsten enzymes" (PDF). Pure & Appl. Chem. 70 (4): 889–896. doi:10.1351/pac199870040889.
  39. ^ Khangulov, S. V.; et al. (1998). "Selenium-Containing Formate Dehydrogenase H from Escherichia coli: A Molybdopterin Enzyme That Catalyzes Formate Oxidation without Oxygen Transfer". Biochemistry. 37 (10): 3518–3528. doi:10.1021/bi972177k. PMID 9521673. {{cite journal}}: Explicit use of et al. in: |author= (help)
  40. ^ Schrader, Thomas; Rienhofer, Annette; Andreesen, Jan R. (1999). "Selenium-containing xanthine dehydrogenase from Eubacterium barkeri". Eur. J. Biochem. 264 (3): 862–71. doi:10.1046/j.1432-1327.1999.00678.x. PMID 10491134.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  41. ^ Attention: This template ({{cite pmid}}) is deprecated. To cite the publication identified by PMID 18096847, please use {{cite journal}} with |pmid=18096847 instead.
  42. ^ Petkewich, Rachel A. (19 January 2009). "Unease over Tungsten". Chemical & Engineering News. 87 (3): 63–65. doi:10.1021/cen-v087n003.p063. ISSN 0009-2347.
  43. ^ Inouye, L. S. et al. (2006). "Tungsten effects on survival, growth, and reproduction in the earthworm, eisenia fetida". Environmental Toxicology & Chemistry. 25 (3): 763. doi:10.1897/04-578R.1.
  44. ^ McQuaid A; Lamand M; Mason J. (1994). "Thiotungstate-copper interactions II. The effects of tetrathiotungstate on systemic copper metabolism in normal and copper-treated rats". J Inorg Biochem. 53 (3): 205. doi:10.1016/0162-0134(94)80005-7.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  45. ^ a b Saunders, Nigel (2004). Tungsten and the Elements of Groups 3 to 7 (The Periodic Table). Chicago, Illinois: Heinemann Library. ISBN 1-4034-3518-9.
  46. ^ "ITIA Newsletter" (PDF). International Tungsten Industry Association. June 2005. Retrieved 2008-06-18.
  47. ^ "ITIA Newsletter" (PDF). International Tungsten Industry Association. December 2005. Retrieved 2008-06-18.
  48. ^ Stevens, Donald G. (1999). "World War II Economic Warfare: The United States, Britain, and Portuguese Wolfram". The Historian. Questia.
  49. ^ Wheeler, L. Douglas (Summer 1986). "The Price of Neutrality: Portugal, the Wolfram Question, and World War II". Luso-Brazilian Review. 23 (1). JSTOR 3513391.
  50. ^ a b Schey, John A. (1987). Introduction to Manufacturing Processes, 2nd ed. McGraw-Hill, Inc.
  51. ^ Erik Lassner, Wolf-Dieter Schubert, Eberhard Lüderitz, Hans Uwe Wolf, "Tungsten, Tungsten Alloys, and Tungsten Compounds" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim. doi:10.1002/14356007.a27_229.
  52. ^ "The Canadian Encyclopaedia". Retrieved 2009-05-05.
  53. ^ Tungsten: The Element, History, Uses and Wedding Bands. (2012)
  54. ^ Blair deLaubenfels; Christy Weber; Kim Bamberg (8 December 2009). Knack Planning Your Wedding: A Step-by-Step Guide to Creating Your Perfect Day. Globe Pequot. pp. 35–. ISBN 978-1-59921-397-2. Retrieved 7 August 2011.
  55. ^ How Tungsten Rings Are Made
  56. ^ Ken Schultz (18 November 2009). Ken Schultz's Essentials of Fishing: The Only Guide You Need to Catch Freshwater and Saltwater Fish. John Wiley and Sons. pp. 138–. ISBN 978-0-470-44431-3. Retrieved 7 August 2011.
  57. ^ "Tungsten Applications – Steel". azom.com. 2000–2008. Retrieved 2008-06-18. {{cite web}}: External link in |publisher= (help)
  58. ^ Ramakrishnan, P. (2007-01-01). "Powder metallurgy for Aerospace Applications". Powder metallurgy: processing for automotive, electrical/electronic and engineering industry. New Age International. p. 38. ISBN 81-224-2030-3.
  59. ^ http://www.wolfmet.com/applications
  60. ^ Dense Inert Metal Explosive (DIME). Defense-update.com. Retrieved on 2011-08-07.
  61. ^ Delmon, Bernard and Froment, Gilbert F. (1999). Hydrotreatment and hydrocracking of oil fractions: proceedings of the 2nd international symposium, 7th European workshop, Antwerpen, Belgium, November 14–17, 1999. Elsevier. pp. 351–. ISBN 978-0-444-50214-8. Retrieved 18 December 2011.{{cite book}}: CS1 maint: multiple names: authors list (link)
  62. ^ Mang, Theo and Dresel, Wilfried (28 May 2007). Lubricants and Lubrication. John Wiley & Sons. pp. 695–. ISBN 978-3-527-61033-4. Retrieved 18 December 2011.{{cite book}}: CS1 maint: multiple names: authors list (link)
  63. ^ Spivey, James J. (2002). Catalysis. Royal Society of Chemistry. pp. 239–. ISBN 978-0-85404-224-1. Retrieved 18 December 2011.
  64. ^ Turrell, Kerry (2004). Tungsten. Marshall Cavendish. p. 24. ISBN 0-7614-1548-3.
  65. ^ Hesse, Rayner W. (2007). "tungsten". Jewelrymaking through history: an encyclopedia. Westport, Conn.: Greenwood Press. pp. 190–192. ISBN 978-0-313-33507-5.
  66. ^ a b Gray, Theo (March 14, 2008). "How to Make Convincing Fake-Gold Bars". Popular Science. Retrieved 2008-06-18.
  67. ^ "Zinc Dimes, Tungsten Gold & Lost Respect", Jim Willie, Nov 18 2009
  68. ^ Largest Private Refinery Discovers Gold-Plated Tungsten Bar, March 2, 2010, Patrick A. Heller, reporting story by ProSieben
  69. ^ Reuters (1983-12-22). "Austrians Seize False Gold Tied to London Bullion Theft". The New York Times. Retrieved 2012-03-25. {{cite news}}: |last= has generic name (help)
  70. ^ Tungsten filled Gold bars, ABC Bullion, Thursday, March 22, 2012
  71. ^ Tungsten Alloy for Gold Substitution, China Tungsten
  72. ^ DeGarmo, E. Paul (1979). Materials and Processes in Manufacturing, 5th ed. New York: MacMillan Publishing.
  73. ^ Curry, Thomas S; Dowdey, James E; Murry, Robert C; Christensen, Edward E (1990-08-01). Christensen's physics of diagnostic radiology. pp. 29–35. ISBN 978-0-8121-1310-5.
  74. ^ Hasz, Wayne Charles et al. "X-ray target" U.S. patent 6,428,904, August 6, 2002
  75. ^ Strigul, N; Koutsospyros, A; Arienti, P; Christodoulatos, C; Dermatas, D; Braida, W (2005). "Effects of tungsten on environmental systems". Chemosphere. 61 (2): 248–58. doi:10.1016/j.chemosphere.2005.01.083. PMID 16168748.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  76. ^ Koutsospyros, A. (2006). "A review of tungsten: From environmental obscurity to scrutiny". Journal of Hazardous Materials. 136 (1): 1–19. doi:10.1016/j.jhazmat.2005.11.007. PMID 16343746. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
  77. ^ Lagarde, F; Leroy, M (2002). "Metabolism and toxicity of tungsten in humans and animals". Metal ions in biological systems. 39: 741–59. PMID 11913143. also reported in Astrid Sigel, Helmut Sigel (2002). Molybdenum and tungsten: their roles in biological processes. CRC Press. p. 741 ff. ISBN 0-8247-0765-6.
  78. ^ Masten, Scott (2003). "Tungsten and Selected Tungsten Compounds – Review of Toxicological Literature" (PDF). National Institute of Environmental Health Sciences. Retrieved 2009-03-19.
  79. ^ Marquet, P.; et al. (1997). "Tungsten determination in biological fluids, hair and nails by plasma emission spectrometry in a case of severe acute intoxication in man". Journal of forensic sciences. 42 (3): 527–30. PMID 9144946. {{cite journal}}: Explicit use of et al. in: |author= (help)
  80. ^ General Electric Co. v. De Forest Radio Co., 28 F.2d 641, 643 (3rd Cir. 1928)
  81. ^ Lakshman D. Guruswamy; Jeffrey A. McNeely (1998). Protection of global biodiversity: converging strategies. Duke University Press. pp. 333–. ISBN 978-0-8223-2188-0. Retrieved 7 August 2011.
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