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Hafnium ( Hf )

Material Information

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Foil Lump Powder Rod Sputtering Target Wire
Foil Lump Powder Rod Sputtering Target Wire

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General Description:  

Discovered in 1923 by D. Coster and G.C. von Hevesey in Copenhagen, Denmark.

Hafnium is a silvery coloured, ductile metal which is found in all minerals containing zirconium. The chemistries of the two metals are similar which makes them difficult to separate, and the properties of each are greatly affected by the presence of the other as an impurity. Both zirconium and hafnium are extracted as the pure metal by reducing the tetrahalide with magnesium, the whole process being carried out under argon as both metals readily combine with other gases (e.g. nitrogen). The abundance of hafnium in the earth's crust is 5.3 ppm.

Hafnium will resist corrosion in air due to the formation of an oxide film, although powdered hafnium will burn in air. It is unaffected by alkalis and acids, with the exception of HF. Hafnium can be used to control recrystallisation of tungsten filaments but its main application is as control rod material in nuclear reactors due to its ability to absorb neutrons. The ability of hafnium to absorb neutrons means that it can sometimes be an annoying impurity in zirconium metal which is used for nuclear engineering.

   

Atomic Properties

Atomic number 72
Atomic radius - Goldschmidt ( nm ) 0.159
Atomic weight ( amu ) 178.49
Crystal structure Hexagonal close packed
Electronic structure Xe 4f14 5d2 6s2
Ionisation potential No. eV
1 7.0
2 14.9
3 23.3
4 33.3
Natural isotope distribution Mass No. %
174 0.2
176 5.2
177 18.5
178 27.1
179 13.8
180 35.2
Photo-electric work function ( eV ) 3.9
Thermal neutron absorption cross-section ( Barns ) 103
Valences shown 4

Electrical Properties

Electrical resistivity @20C ( µOhmcm ) 32.2
Temperature coefficient @0-100C ( K-1 ) 0.0044
Superconductivity critical temperature ( K ) 0.128

Mechanical Properties

Material condition Soft Hard Polycrystalline
Bulk modulus ( GPa )     109
Hardness - Vickers 150-180
Poisson's ratio     0.26
Tensile modulus ( GPa )     141
Tensile strength ( MPa ) 445 745
Yield strength ( MPa ) 240 365

Physical Properties

Boiling point ( C ) 4602
Density @20C ( g cm-3 ) 13.1
Melting point ( C ) 2227

Thermal Properties

Coefficient of thermal expansion @0-100C ( x10-6 K-1 ) 6.0
Latent heat of evaporation ( J g-1 ) 3700
Latent heat of fusion ( J g-1 ) 122
Specific heat @25C ( J K-1 kg-1 ) 146
Thermal conductivity @0-100C ( W m-1 K-1 ) 23.0

Buy Hafnium on-line

We stock and supply the following standard forms:
Foil Lump Powder Rod Sputtering Target Wire
Foil Lump Powder Rod Sputtering Target Wire

Choose a form to search our on-line catalogue  

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