Superconductivity in the actinides

The trends in the occurrence of superconductivity in actinide materials are discussed. Most of them seem to show simple transition metal behavior. However, the superconductivity of americium proves that the f electrons are localized in that element and that ''actinides'' is the correct name for this row of elements. Recently the superconductivity of UBe13 and UPt3 has been shown to be extremely unusual, and these compounds fall in the new class of compounds now known as heavy fermion materials. (orig.)