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1803 von S. Tennant in London, UK, entdeckt.
[Lateinisch, iris = Regenbogen]
French: iridium
English: iridium
Italian: iridio
Spanish: iridio
Beschreibung: Hartes, glänzendes, silberfarbiges Metall der Platingruppe. Beständig gegen Luft und Wasser, inert gegenüber allen Säuren, von geschmolzenem NaOH wird es angegriffen. Verwendet für Speziallegierungen und Zündkerzen.
State: | single crystal |
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Crystal structure: | fcc |
Production method: | Floating zone |
Standard size: | diameter 8-10mm thickness 1-2 |
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: | 99.99% |
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: | 22.5 g/cm3 |
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Melting point: | 2409.85 °C / 2683 °K |
Boiling point: | 4129.85 °C / 4403 °K |
Molar volume: | 8.57 cm3 |
Thermal conductivity: | 147 [300 K] Wm-1K-1 |
Coefficient of linear thermal expansion: | 6.4 x 10-6 K-1 |
Electrical resistivity: | 5.3x 10-8 [293 K] Wm |
Mass magnetic susceptibility: | +1.67 x 10-9(s) kg-1m3 |
Young's modulus: | 528 GPa |
Rigidity modulus: | 209 GPa |
Bulk modulus: | 371 GPa |
Poisson's ratio: | 0.26 GPa |
Radii: | Ir4+ 66; Ir3+ 75; Ir2+ 89; atomic 136; covalent 12 |
Electronegativity: | 2.20 (Pauling); 1.55 (Allred); 5.4 eV (absolute) |
Effective nuclear charge: | 3.90 (Slater); 10.57 (Clementi); 15.33 (Froese-Fischer) |
Number of Isotopes (incl. nuclear isomers): | 40 |
Issotope mass range: | 170 -> 198 |
Crystal structure, (cell dimentions / pm), space group | fcc |
X-ray diffraction: mass absorption coefficients: | CuKα 193 (µ/r) / cm2g-1 MoKα 110 (µ/r) / cm2g-1 |
Neutron scattering length: | 1.06 b/10-12 cm |
Thermal neutron capture cross-section: | 425 sa / barns |
Biological role: | none |
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Toxicity | |
Toxic intake: | the pure metal is clinically inet; data on compounds is sparse. |
Lethal intake: | LD50 (chloride, oral, mouse) = 8.12 mg kg-1 |
Hazards: | Indium chloride is moderately toxic by ingestion, but most compunds are insoluble and not absorbed by the body. |
Level in humans | |
Blood: | n.a., but very low |
Bone: | n.a. |
Liver: | n.a. |
Muscle: | c. 2 x 10-5 p.p.m. |
Daily dietary intake: | n.a., but very low |
Total mass of element in average [70 kg] person: | n.a. |
Mineral | Formula | Density | Hardness | Crystal apperance |
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Iridium | IR | 22.4 | 6 - 6.5 | cub., met. white |
Iridosmine | (Os, Ir) | 20 | 6 - 7 | hex., met. white/grey |
Osmiridium | (Ir, Os) | 20 | 6 - 7 | cub., met. white |
Chief ore: | osmiridium; also found with platinum ores |
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World production: | 3 tonnes/year |
Main mining areas: | Canada for native element; see also platinum. |
Reserves: | n.a. |
Specimen: | available as foil, powder, spronge or wire. Safe. |
Abundances | |
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Sun: | 7.1 (relative to H = 1 x 1012) |
Earth's crust: | 3 x 10-6 p.p.m. |
Seawater: | |
Residence time: | |
Classification: | |
Oxidation state: |