Index

Molybdenum ( Mo )

Material Information

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General Description:  

Discovered in 1871 by P.J. Hjelm in Uppsala, Sweden.

Molybdenum is a lustrous, silvery coloured metal which has an abundance of 1.5 ppm in the earth's crust. In many instances, it shows a resemblance to tungsten with which it tends to be paired in the transition series in the periodic table, but their chemistries tend to show more distinct differences than might be expected.

Molybdenum has a high melting point and applications for the pure metal take advantage of this; for example, the pure material is used as resistance heating elements in furnaces, as filament supports in electric lamps, and as electrodes for mercury vapour lamps. Molybdenum is used as an alloying agent in certain grades of steel, Permalloys and Stellites (a series of alloys which contain varying proportions of Cr, Co, W and Mo, are very hard and are used in cutting tools and to protect surfaces subject to heavy wear).

   

Atomic Properties
     
Atomic number 42
Atomic radius - Goldschmidt ( nm ) 0.140
Atomic weight ( amu ) 95.94
Crystal structure Body centred cubic
Electronic structure Kr 4d5 5s1
Ionisation potential No. eV
1 7.10
2 16.15
3 27.2
4 46.4
5 61.2
6 68
Natural isotope distribution Mass No. %
92 14.8
94 9.3
95 15.9
96 16.7
97 9.6
98 24.1
100 9.6
Photo-electric work function ( eV ) 4.2
Thermal neutron absorption cross-section ( Barns ) 2.65
Valences shown 2, 3, 4, 5, 6

Electrical Properties
     
Electrical resistivity @20C ( µOhmcm ) 5.7
Temperature coefficient @0-100C ( K-1 ) 0.00435
Superconductivity critical temperature ( K ) 0.915
Thermal emf against Pt (cold 0C - hot 100C) ( mV ) +1.45

Mechanical Properties
     
Material condition Soft Hard Polycrystalline
Bulk modulus ( GPa ) 261.2
Hardness - Vickers 200 250
Poisson's ratio 0.293
Tensile modulus ( GPa ) 324.8
Tensile strength ( MPa ) 485-550 620-690
Yield strength ( MPa ) 415-450 550

Physical Properties
     
Boiling point ( C ) 4612
Density @20C ( g cm-3 ) 10.22
Melting point ( C ) 2617

Thermal Properties
     
Coefficient of thermal expansion @0-100C ( x10-6 K-1 ) 5.1
Latent heat of evaporation ( J g-1 ) 6153
Latent heat of fusion ( J g-1 ) 290
Specific heat @25C ( J K-1 kg-1 ) 251
Thermal conductivity @0-100C ( W m-1 K-1 ) 138


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.

Standard products are available in these forms
Foil Insulated-Wire Lump Mesh Microfoil Powder Rod Single-Crystal Sputtering-Target Tube Wire

Choose a form to search our on-line catalogue