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Uranium ( U )

Material Information

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General Description:  

Uranium was discovered in 1789 by M.H. Klaproth in Berlin, Germany.

Although uranium is the longest known member of the actinide group of metals, it attracted scant attention until the discovery of uranium fission in 1939. It is now of vital importance as a nuclear fuel. Uranium occurs naturally as two main isotopes, 238U (99.3%) and 235U (0.7%), along with a trace of a third isotope, 233U. Separation of the isotopes is achieved by conversion to the hexafluorides. The 235U isotope is the more important as this reacts with a neutron by fission to form lighter nuclei, the reaction being accompanied by the release of a considerable amount of energy and more neutrons which, in turn, fission more 235U and permits the build up of a chain reaction. The energy released as a result of this nuclear process is the order of a million times greater than that resulting from burning fossil fuel and it is for this reason that there is substantial interest in nuclear fission.

238U is also important in a nuclear reactor as it can absorb neutrons itself to produce heavier elements, the most important of which is plutonium, another nuclear fuel. Under the correct conditions, more plutonium can be produced from 238U than the amount of 235U consumed, and such an arrangement is found in a "breeder" type of nuclear reactor.

   

Atomic Properties

Atomic number 92
Atomic radius - Goldschmidt ( nm ) 0.138
Atomic weight ( amu ) 238.0289
Crystal structure Orthorhombic
Electronic structure Rn 5f3 6d1 7s2
Ionization potential No. eV
1 6.19
Natural isotope distribution Mass No. %
234 0.005
235 0.720
238 99.275
Photo-electric work function ( eV ) 3.6
Thermal neutron absorption cross-section ( Barns ) 7.6
Valences shown 2, 3, 4, 5, 6

Electrical Properties

Electrical resistivity @20C ( µOhmcm ) 27
Temperature coefficient @0-100C ( K-1 ) 0.0034

Mechanical Properties

Material condition Soft Hard Polycrystalline
Bulk modulus ( GPa )     97.9
Hardness - Vickers 187 250
Izod toughness ( J m-1 ) 19 15
Poisson's ratio     0.20
Tensile modulus ( GPa )     175.8
Tensile strength ( MPa ) 385 580
Yield strength ( MPa ) 190 250

Physical Properties

Boiling point ( C ) 3818
Density @20C ( g cm-3 ) 19.05
Melting point ( C ) 1132

Thermal Properties

Coefficient of thermal expansion @0-100C ( x10-6 K-1 ) 13.4
Latent heat of evaporation ( J g-1 ) 1753
Latent heat of fusion ( J g-1 ) 52.5
Specific heat @25C ( J K-1 kg-1 ) 116
Thermal conductivity @0-100C ( W m-1 K-1 ) 27.5

Buy Uranium on-line

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

Choose a form to search our on-line catalog  

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