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Thorium ( Th )

Material Information

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General Description:  

Thorium was discovered in 1829 by J.J. Berzelius in Stockholm.

Thorium is a dark grey, radioactive metal of which the principal source is the ore, monazite, a complex phosphate of thorium, uranium, cerium and lanthanides. The metal is soft and ductile and is extracted by precipitation as the hydroxide, along with cerium and uranium; separation is achieved by further extraction with tributyl phosphate from an acid solution. The metal is made by calcium reduction of the oxide or fluoride, and pure thorium can be obtained by decomposing ThI4 on a hot filament (the Van Arkel process).

Thorium is used as an alternative reactor fuel to uranium, thorium being converted readily into uranium in the reactor. Thorium is extremely efficient as an energy source, the earthly reserves of thorium containing more energy than all other fossil fuel sources combined.
   

Atomic Properties

Atomic number 90
Atomic radius - Goldschmidt ( nm ) 0.180
Atomic weight ( amu ) 232.0381
Crystal structure Face centred cubic
Electronic structure Rn 6d2 7s2
Ionization potential No. eV
1 6.95
2 11.5
3 20.0
4 28.8
Natural isotope distribution Mass No. %
232 100
Photo-electric work function ( eV ) 3.5
Thermal neutron absorption cross-section ( Barns ) 7.4
Valences shown 2, 3, 4

Electrical Properties

Electrical resistivity @20C ( µOhmcm ) 14.0
Temperature coefficient @0-100C ( K-1 ) 0.0040
Superconductivity critical temperature ( K ) 1.38
Thermal emf against Pt (cold 0C - hot 100C) ( mV ) -0.13

Mechanical Properties

Material condition Soft Hard Polycrystalline
Bulk modulus ( GPa )     54
Hardness - Vickers 38 70
Izod toughness ( J m-1 ) 41 6
Poisson's ratio     0.26
Tensile modulus ( GPa )     78.3
Tensile strength ( MPa ) 115 305
Yield strength ( MPa ) 48 295

Physical Properties

Boiling point ( C ) 4790
Density @20C ( g cm-3 ) 11.72
Melting point ( C ) 1750

Thermal Properties

Coefficient of thermal expansion @0-100C ( x10-6 K-1 ) 11.2
Latent heat of evaporation ( J g-1 ) 2202
Latent heat of fusion ( J g-1 ) 82.8
Specific heat @25C ( J K-1 kg-1 ) 113
Thermal conductivity @0-100C ( W m-1 K-1 ) 54
All information and technical data are given as a guide only. Although every effort has been made to ensure that the information is correct, no warranty is given as to its completeness or accuracy.

Buy Thorium on-line

We stock and supply the following standard forms:
Foil Wire
Foil Wire

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