 |
|
|
|
|
Chromium single crystal 24Cr51.996
Discovered and isolated in 1780 by Nicholas Louis Vauquelin at Paris, France.
[Greek: chroma = colour]
French: chrome
German: chrom
Italian: cromo
Spanish: cromo
|
Description: Chromium is a hard, blue-white metal. It will dissolve in HCl and H2SO4 but not in HNO3, H3PO4 or HClO4 due to reaction and formation of a protective layer on the surface. Chromium can be polished to a high shine and resists oxidation in air. It main uses are in alloys, chrome plating and metal ceramics.
|
Metal single crystal properties
| State: |
single crystal |
|
| Crystal structure: |
bcc |
|
| Production method: |
Floating zone |
|
| Standard size: |
diameter 6-10mm
thickness 1-2mm |
|
| Orientation: |
(100), (110) and (111) |
|
| Orientation accuracy: |
<2°, <1°, <0.5° or <0.1d° |
|
| Polishing: |
as cut, one or two sides polished |
|
| Roughness of surface: |
<0.03µm |
|
| Purity: |
99.999% |
|
| Typical analysis (ppm): |
Ag < 0.10
C 10.0
Ca 0.01
Cd < 0.10
Cl 1.60
Co < 0.10
Cu < 0.10
Fe 18.0
H < 2.00 |
Mg < 0.10
Mn < 0.10
Mo < 0.20
N < 5.00
Na < 0.10
Ni 3.00
O < 5.00
Si 4.80
Cr balance |
Further Materials properties
| Crystal structure: |
(cell dimensions/pm), space group,
b.c.c. (a=288.46), Im3m |
| X-ray diffractions mass absorption coefficients: |
CuKa 260 (µ/r) / cm2g-1
MoKa 31.1 (µ/r) / cm2g-1 |
| Neutron scattering length: |
0.3635 b/10-12 cm |
| Thermal neutron capture cross-section: |
3.1 sa / barns
|
| Density: |
7.19 g/cm3 |
| Melting point: |
1856.85 ±20 °C / 2130 ±20 °K |
| Boiling point: |
2671.85 °C / 2945 °K |
| Molar volume: |
7.23 cm3 |
| Thermal conductivity: |
93.7 [300 K] Wm-1K-1 |
| Coefficient of linear thermal expansion: |
6.2 x 10-6 K-1 |
| Electrical resistivity: |
12.7x10-8 [273 K] Wm |
| Mass magnetic susceptibility: |
+4.45 x 10-8(s) kg-1m3 |
| Young's modulus: |
279 GPa |
| Rigidity modulus: |
115.3 GPa |
| Bulk modulus: |
160.2 GPa |
| Poisson's ratio: |
0.21 GPa |
| Radii: |
Cr4+ 56; Cr3+ 64; Cr2+ 84; atomic 125 |
| Electronegativity: |
1.66 (Pauling); 1.56 (Allred); 3.72 eV (absolute) |
| Effective nuclear charge: |
3.45 (Slater); 5.13 (Clementi); 6.92 (Froese-Fischer) |
| Number of Isotopes (incl. nuclear isomers): |
13 |
| Issotope mass range: |
45 -> 57 |
Biological data
| Biological role: |
Essential to some species, including humans; it is also stimulatory. |
| Toxicity |
|
| Toxic intake: |
200 mg |
| Lethal intake: |
metal, oral, human = 70 mg kg-1. LD50 (acetate, oral, rat) = 11000 mg kg-1 |
| Hazards: |
Chromium is a human poison by ingestion, it is also a suspected carcinogen. Chromates have a corrosive action on skin an tissue |
| Level in humans |
|
| Blood: |
0.006 - 0.11 mg dm-3 |
| Bone: |
0.1 - 0.33 p.p.m. |
| Liver: |
0.02 - 3.3 p.p.m. |
| Muscle: |
0.024 - 0.84 p.p.m. |
| Daily dietary intake : |
0.01 - 1.2 mg |
Total mass of element in average
[70 kg] person: |
14 mg |
Geological data
| Minerals: |
|
| Mineral |
Formula |
Density |
Hardness |
Crystal apperance |
| Chromite |
FeCr2O4 |
4.7 |
5.5 |
cub., compacted, met. black |
| Chrocoite |
PbCrO4 |
6.0 |
2.5 - 3 |
mon., adam./vit. red-orange |
| Chief ore: |
chromite
|
| World production: |
20000 tonnes/year (chromium metal); 9.6 x 106 (chromite ore) |
| Main mining areas: |
Turkey, South Africa, Zimbabwe, Rusia, Philippines. |
| Reserves: |
1 x 109 |
| Specimen: |
available as chips, chunks, crystallites or powder. Safe.
|
| Abundances |
|
| Sun: |
5.13 x 105 (relative to H = 1 x 1012) |
| Earth's crust: |
c. 100 ppm |
| Seawater: |
|
| Atlantic surface: |
1.8 x 10-4 p.p.m. |
| Atlantic deep: |
2.3 x 10-4 p.p.m. |
| Pacific surface: |
1.5 x 10-4 p.p.m. |
| Pacific deep: |
2.5 x 10-4 p.p.m. |
| Residence time:: |
10000 years |
| Classification: |
recycled |
| Oxidation state: |
VI |
Other sizes and specifications on request
© 1996 - 2008 MaTecK GmbH - Im Langenbroich 20 - D-52428 Juelich - phone: +49 (0) 2461 / 9352-0 - fax: +49 (0) 2461 / 9352-11 - Contact: info@mateck.de
|
|
|
|
