Hafnium (Hf)

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Hafnium 72Hf178.49

1923 von D. Coster und G.C. von Hevesey in Kopenhagen, Dänemark, entdeckt.

 [Latein: Hafnia = Kopenhagen]

  French: hafnium
   English: hafnium
  Italian: afnio
  Spanish: hafnio

Beschreibung: Glänzendes, silberfarbendes, duktiles Metall. Da es durch eine Oxidschicht passiviert wird, korrodiert es nicht, als Pulver jedoch verbrennt es in Luft. Es wird nicht von Säuren (außer HF) und Laugen angegriffen. Verwendet für Regelstäbe in Kernreaktoren, Hochtemperaturlegierungen und Keramiken.

Hafnium single crystal properties

 

State: Single crystal
Crystal structure: hexagonal
Production method: Floating zone
Standard size: diameter 7-8mm
thickness 1mm
Orientation: (0001)
Orientation accuracy: <2°, <1°, <0.4° or <0.1°
Polishing: as cut, one or two sides polished
Roughness of surface: <0.03 µm
Purity: 99.99%

 

 

Further Materials properties

 

Crystal structure: (cell dimensions/pm), space group
a-Hf h.c.p. (a=319.46, c=505.10), P63/mmc
b-Hf cubic (a=362)
T(a -> a)=2033 K
X-ray diffractions mass absorption coefficients: CuKa 159 (µ/r) / cm2g-1
MoKa 91.7 (µ/r) / cm2g-1
Neutron scattering length: 0.777 b/10-12 cm
Thermal neutron capture cross-section: 104 sa / barns
Density: 13.1 kg/m-3 [293 K]; 2390 [liquid at m.p.]
Melting point: 2229.85 °C / 2503 °K
Boiling point: 5196.85 °C / 5470 °K
Molar volume: 13.41 cm3
Thermal conductivity: 23.0 [300 K] Wm-1K-1
Coefficient of linear thermal expansion: 5.9 x 10-6 K-1
Electrical resistivity: 35.1 x 10-8 [293 K] Wm
Mass magnetic susceptibility: +5.3 x 10-9(s) kg-1m3
Young's modulus: 141 GPa
Rigidity modulus: 56 GPa
Bulk modulus: 109 GPa
Poisson's ratio: 0.26 GPa
Radi: Hf3+ 84; atomic 156; covalent 144
Electronegativity: 1.3 (Pauling); 1.23 (Allred); 3.8 eV (absolute)
Effective nuclear charge: 3.15 (Slater); 9.16 (Clementi); 13.27 (Froese-Fischer)
Number of Isotopes (incl. nuclear isomers): 33
Isotope mass range: 158 -> 184

 

 

Biological data

 

Biological role: none
Toxicity  
Toxic intake: hafnium and hafnium salts generally have low toxicity
Lethal intake: LD50 (chloride, oral, rat)=2400 mg kg-1
Hazards: Hafnium is poorly absorbed by the body and poisoning by hafnium compounds is very rare.
Level in humans  
Organs: n.a.
Daily dietary intake: n.a.
Total mass of element in average
[70 kg] person:		 n.a.

 

Geological data

 

Minerals:Many minerals are known, and aluminium is present in many other minerals
MineralFormulaDensityHardnessCrystal apperance
Hafnon  HfSiO4  6.97  n.a.  tet.

 

Chief ore: hafnium is obtained as a by-product of zirconium refining
World production: c. 50 tonnes/year
Main mining areas: see zirconium
Reserves: n.a.
Specimen: available as foil, pieces, powder sponge or wire. Safe.

 

Abundances  
Sun: 6 (relative to H = 1 x 1012)
Earth's crust: 5.3 ppm
Seawater: 7 x 10-6 ppm
Residence time: n.a.
Classification: n.a.
Oxidation state: IV

 

Other sizes and specifications on request


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