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Barium (Ba)
Wir sind führender Hersteller und Lieferant von Forschungsmaterialien
Barium 56Ba137.327
Von Sir Humphry Davy 1808 in London, UK, dargestellt.
[Greek: barys = heavy, Latin: barium]
French: baryum
English: Barium
Italian: bario
Spanish: bario
Beschreibung: Relativ weiches, silberweißes Metall. Man erhält es aus BaO durch Erhitzen mit Aluminium. Wird von Luft und Wasser angegriffen. Verwendung überwiegend als BaSO4 in Bohrflüssigkeiten zur Öl- und Gas-Exploration; in kleinen Mengen für Farben, Glas usw.
Further Materials properties
| Crystal structure: |
(cell dimensions/pm), space group, b.c.c. (a=502.5), Im3m, high pressure form (a=390.1, c=615.5), P63/mmc |
|---|---|
| X-ray diffractions mass absorption coefficients: | CuKa 330 (µ/r) / cm2g-1 MoKa 43.5 (µ/r) / cm2g-1 |
| Neutron scattering length: | 0.507 b/10-12 cm |
| Thermal neutron capture cross-section: | 1.3 sa / barns |
| Density: | 3594 kg/m-3 [293 K] 3325 [liquid at m.p.] |
| Melting point: | 728.85 °C / 1002°K (α, under pressure) |
| Boiling point: | 1636.85 °C / 1910°K |
| Molar volume: | 38.21 cm3 |
| Thermal conductivity: | 18.4 [300 K] Wm-1K-1 |
| Coefficient of linear thermal expansion: | (18.1- 21.) x 10-6 K-1 |
| Electrical resistivity: | 50 x 10-8 [273 K] Ωm |
| Mass magnetic susceptibility: | +1.9 x 10-9 kg-1m3 |
| Young's modulus | 12.8 GPa |
| Rigidity modulus | 4.86 GPa |
| Bulk modulus | n.a. |
| Poisson's ratio | 0.28 GPa |
| Radi: | Ba2+ 143; atomic 217; covalent 198 |
| Electronegativity: | 0.89 (Pauling); 0.97 (Allred); 2.4 eV (absolute) |
| Effective nuclear charge: | 2.85 (Slater); 7.58 (Clementi); 10.27 (Froese-Fischer) |
| Number of Isotopes (incl. nuclear isomers): | 37 |
| Isotope mass range: | 117 -> 148 |
Biological data
| Biological role: | None, but Barium is stimulatory |
|---|---|
| Toxicity | |
| Toxic intake: | 100 - 200 mg |
| Lethal intake: | LD50 (BaCO3, oral, rat) = 418 mg kg-1 |
| Hazards: | Barium sulfate is insoluble and used for body imaging, but soluble barium salts are highly toxic causing vomiting, colic, diarrhoea, tremors, paralysis etc. |
| Level in humans | |
| Blood: | 0.068 mg dm-3 |
| Bone: | 3 - 70 ppm |
| Liver: | 0.04 - 1.2 ppm |
| Muscle: | 0.09 ppm |
| Daily dietary intake: | 0.6 - 1.7 mg |
| Total mass of element in average [70 kg] person: |
22 mg |
Geological data
| Minerals: | ||||
|---|---|---|---|---|
| Mineral | Formula | Density | Hardness | Crystal apperance |
| Barite | BaSO4 | 4.50 | 3 - 3.5 | orth., vitr./res. colourless-yellow |
| Benitoite (gemstone) | BaTiSi3O2 | 3.6 | 6.3 | hex., trans. blue |
| Witherite | BaCO3 | 4.219 | 3-3.5 | orth., vitr./res. colourless/grey |
| Chief ores: | barite mainly, witherite occasionally |
|---|---|
| World production: | 6 x 106 (barium ores) tonnes/year |
| Main mining areas: | UK, Italy, Czech Republic (Pribram), USA, Germany |
| Reserves: | 450 x 106 tonnes |
| Specimen: | available as granules, rods or stick. Warning! |
| Abundances | |
|---|---|
| Sun: | 123 (relative to H = 1 x 1012) |
| Earth's crust: | 500 ppm |
| Seawater | |
| Atlantic surface: | 4.7 x 10-3 ppm |
| Atlantic deep: | 9.3 x 10-3 ppm |
| Pacific surface: | 4.7 x 10-3 ppm |
| Pacific deep: | 20.0 x 10-3 ppm |
| Residence time: | 10 000 years |
| Classification: | recycled |
| Oxidation state: | II |
Source: Emsley, J. (1998) The Elements (3rd Edition)
Other sizes and specifications on request
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