We review our current understanding of the mechanical, electronic and structural properties of the element uranium, with the focus on the low-temperature regime in which the α-phase is stable We start with a historical perspective, as the need for understanding the metallurgy of uranium so that its use as a nuclear fuel in the late 1940s could be optimized led to an increasing number of experiments aimed at exploring the solid-state properties This was further accelerated when single crystals became available in the 1950s and when the superconductivity of the low-temperature α phase became the subject of controversy in the 1960s The late 1960s and 1970s saw a considerable effort towards understanding the nature of the 5f electrons around the uranium nucleus The increasing availability of sophisticated methods in computational physics first showed in the 1970s that the 5f electrons should be treated as itinerant, and the decade ended with the observation (by neutron diffraction) of a subtle pe

The solid-state properties of uranium A historical perspective and review

The superconducting transition temperature of single-crystal and polycrystal uranium has been determined as a function of hydrostatic pressure to 24 kbar. Although the general form of theT c (P) variation is similar for the two types of material, features are present in the detailed behavior for the single-crystal samples which are not found for polycrystal samples. These features are presumed to be associated with the first-order transitions observed at zero pressure. A low-temperature phase diagram has been constructed and the electronic nature of the various phases is discussed.

Superconductivity and phase transitions in single-crystal and polycrystal α-U at high pressure

Electrical Resistivity of Alpha Uranium at Low Temperatures

Specific heat of α-uranium

The first 30 years of research on the physical properties of α-U

The low temperature thermal expansion behaviour of α-Uranium

This review covers the effects of self-irradiation damage on the physical properties of the α-emitting actinide metals Th, Pa, U, Np, and Pu and some of their alloys: compounds are not considered. The damage to the lattice caused by the α-particles and recoiling nuclei anneals out below room temperature so that the experiments have to be carried out at cryogenic temperatures, mainly in liquid helium. The properties that have been studied include resistivity, length, lattice parameters, thermal conductivity, and specific heat. Most work has been done on the resistivities. These increase with time, showing an exponential approach to saturation after some thousands of hours. In addition to the main exponential law, smaller exponential terms can be separated in some cases, indicating that more than one damage mechanism occurs. The lengths and lattice parameters also saturate exponentially. For most materials these increase but the metastable phases β- and δ-plutonium contract with time. Because the α-...

J.A. Lee

Papers

The low temperature thermal expansion behaviour of α-Uranium

Self-Irradiation Damage in Actinide Metals and Alloys