Actinide Materials Research Supported by the Office of Basic Energy Sciences, U.S. Department of Energy

摘要

The fundamental research topic in actinide chemistry and materials sciences is the role that the 5f electrons play in bond formation, which provides the central focus for DOE BES-supported actinide science. Structural systematics of the actinide metals, oxides, and other compounds as a function of atomic number are well established. Magnetic measurements have shown that the light actinide metals have delocalized 5f orbitals (i.e., the 5f electrons form bands), whereas the f electrons become localized at americium. Thus, the magnetic behavior of the first part of the actinide series resembles that of the d transition metals whereas the heavier actinides exhibit behavior similar to the rare earth metals. Spectroscopic results have established electronic energy levels, crystal field splitting, and near-neighbor coordination. The 5f orbitals participate in the band structure of materials that contain the light actinide metals and some of their intermetallic compounds, and perhaps in molecular compounds. Molecular-level information on the geometry and bonding in solids, at surfaces, and in clusters can now be obtained at BES-supported facilities.