Physical Properties of Actinide Metals From Am on

We assume, in this case, that the conduction band has become normal (that is, it has no longer any 5 f character). Thus, physical properties may be usefully compared with those of the lanthanides. In Table 5 we report known basic properties (metallic radii, crystal structures, melting temperatures and enthalpies of sublimation) of the transplutonium metals. 

Examination of this table confirms what could already be guessed from atomic calculations only Am, Cm and to a less extent Bk can be considered similar to normal 

although it is safe to assume that the 5f states are localized states, excited f states are never far above the Fermi energy. They will, therefore, influence the electronic properties and high temperature phases of Cf and Es (which, with a metal radius R = 2.0 A seem to have attained divalency). 

The situation above described has important consequences in the understanding of the physical properties not only of heavy actinide metals, but also of their compounds. We can expect e.g. that the occurence of valence fluctuations should be quite common in Am, Bk and Cf compounds (to limit ourselves to the sufficiently stable isotopes) as well as in Cf metal itself  

Curium metal was found to be antiferromagnetic Its Curie-WeiB behaviour above the Neel point is in good agreement with the localized picture (pett = 8 Pb as in Gd metal). In the case of Bk, again the Curie-WeiB law gives the expected effective moment value  

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