Wir sind führender Hersteller und Lieferant von Forschungsmaterialien
1783 von J.J. und F. Elhuijar in Vergara, Spanien, dargestellt.
[Der englische Name tungsten kommt vom Schwedischen tung sten = schwerer Stein; Wolfram kommt vom Mineral Wolframit]
French: tungstène
German: wolfram
Italian: wolframio (tungsteno)
Spanish: wolframio
Beschreibung: Man erhält es als mattgraues Pulver, das schwer zu schmelzen ist. Das Metall ist glänzend und silberweiß. Durch Sauerstoff, Säuren und Alkalien wird es nicht angegriffen. Verwendung für Legierungen, Glühdrähte und Schneidwerkzeuge.
State: | single crystal |
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Crystal structure: | bcc |
Production method: | Floating zone |
Standard size: | diameter 8-12mm thickness 1-2mm |
Orientation: | (100), (110) and (111) |
Orientation accuracy: | <2°, <1°, <0.4° or <0.1° |
Polishing: | as cut, one or two sides polished |
Roughness of surface: | <0.03µm |
Purity: | 99.999% |
Typical analysis (ppm): | C 3 H < 1 O 9 N < 5 Cu 1.60 Fe 1.80 Ni < 1 Pb 0.30 Si 0.30 Ga, Hf and Ta are below the detection limit |
Density: | 19.3 g/cm3 |
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Melting point: | 3406.85±20 °C / 3680±20 °K |
Boiling point: | 5656.85 °C / 5930 °K |
Molar volume: | 9.53 cm3 |
Thermal conductivity: | 174 [300 K] Wm-1K-1 |
Coefficient of linear thermal expansion: | 4.59 x 10-6 K-1 |
Electrical resistivity: | 5.65x 10-8 [300 K] Wm |
Mass magnetic susceptibility: | +4.0 x 10-9(s) kg-1m3 |
Young's modulus: | 411 GPa |
Rigidity modulus: | 160.6 GPa |
Bulk modulus: | 311 GPa |
Poisson's ratio: | 0.28 GPa |
Radii: | W6+ 62; W4+ 68; atomic 137; covalent 130 |
Electronegativity: | 2.36 (Pauling); 1.40 (Allred); 4.40 eV (absolute) |
Effective nuclear charge: | 4.35 (Slater); 9.85 (Clementi); 14.22 (Froese-Fischer) |
Number of Isotopes (incl. nuclear isomers): | 29 |
Issotope mass range: | 160 -> 190 |
Crystal structure, (cell dimentions / pm), space group | bcc |
X-ray diffraction: mass absorption coefficients: | CuKα 172 (µ/r) / cm2g-1 MoKα 99.1 (µ/r) / cm2g-1 |
Neutron scattering length: | 0.486 b/10-12 cm |
Thermal neutron capture cross-section: | 18.3 sa / barns |
Biological role: | none |
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Toxicity | |
Toxic intake: | mildly toxic |
Lethal intake: | LD50 (metal, rat) = 2000 mg kg-1 |
Hazards: | Tungsten dust is a skin and eye irritant and an experimental teratogen. |
Level in humans | |
Blood: | 0.001 mg dm-3 |
Bone: | 0.00025 p.p.m. |
Liver: | n.a. |
Muscle: | n.a. |
Daily dietary intake: | 0.001 - 0.015 mg |
Total mass of element in average [70 kg] person: | c. 0.02 mg |
Mineral | Formula | Density | Hardness | Crystal apperance |
---|---|---|---|---|
Ferberite | FeWO4 | 7.40 | 4 - 4.5 | mon., met. black |
Scheelite | CaWO4 | 6.10 | 4.5 5 | tet., vit./adam. colourless |
Wolframite | (Fe, Mn) WO4 | 7.3 | 4 - 4.5 | mon., sub-met./adam. greyish-black |
Chief ore: | scheelite and wolframite |
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World production: | 45 100 tonnes/year |
Main mining areas: | China, Malaysia, Burma, Bolivia, Canada, Australia, Japan, USA |
Reserves: | 1.5 x 106 tonnes |
Specimen: | available as foil, powder, rod or wire. Safe. |
Abundances | |
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Sun: | 50 (relative to H = 1 x 1012) |
Earth's crust: | 1 p.p.m. |
Seawater: | |
Residence time: | |
Classification: | |
Oxidation state: | VI |