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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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All sourcesNASA NTRSDOE OSTI
DOE OSTI2014

Delocalization and occupancy effects of 5f orbitals in plutonium intermetallics using L3-edge resonant X-ray emission spectroscopy

Although actinide (An) L3 -edge X-ray absorption near-edge structure (XANES) spectroscopy has been very effective in determining An oxidation states in insulating, ionically bonded materials, such as in certain coordination compounds and mineral systems, the technique fails in systems featuring more delocalized 5f orbitals, especially in metals. Recently, actinide L3-edge resonant X-ray emission spec- troscopy (RXES) has been shown to be an effective alternative. This technique is further demonstrated here using a parameterized partial unoccupied density of states method to quantify both occupancy and delocalization of the 5f orbital in ?-Pu, ?-Pu, PuCoGa5 , PuCoIn5 , and PuSb2. These new results, supported by FEFF calculations, highlight the effects of strong correlations on RXES spectra and the technique?s ability to differentiate between f-orbital occupation and delocalization.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on PuGa5Co by Materials Project

PuCoGa5 crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. Pu is bonded to twelve Ga atoms to form PuGa12 cuboctahedra that share corners with four equivalent PuGa12 cuboctahedra, faces with four equivalent PuGa12 cuboctahedra, and faces with four equivalent GaPu4Ga8 cuboctahedra. There are eight shorter (2.94 Å) and four longer (2.98 Å) Pu–Ga bond lengths. Co is bonded in a body-centered cubic geometry to eight Ga atoms. All Co–Ga bond lengths are 2.48 Å. There are five inequivalent Ga sites. In the first Ga site, Ga is bonded in a 4-coordinate geometry to two equivalent Pu, two equivalent Co, and seven Ga atoms. There are a spread of Ga–Ga bond distances ranging from 2.62–2.98 Å. In the second Ga site, Ga is bonded in a 4-coordinate geometry to two equivalent Pu, two equivalent Co, and seven Ga atoms. There are two shorter (2.94 Å) and four longer (2.98 Å) Ga–Ga bond lengths. In the third Ga site, Ga is bonded in a 4-coordinate geometry to two equivalent Pu, two equivalent Co, and seven Ga atoms. There are one shorter (2.62 Å) and two longer (2.94 Å) Ga–Ga bond lengths. In the fourth Ga site, Ga is bonded in a 4-coordinate geometry to two equivalent Pu, two equivalent Co, and seven Ga atoms. Both Ga–Ga bond lengths are 2.94 Å. In the fifth Ga site, Ga is bonded to four equivalent Pu and eight Ga atoms to form GaPu4Ga8 cuboctahedra that share corners with four equivalent GaPu4Ga8 cuboctahedra, faces with four equivalent PuGa12 cuboctahedra, and faces with four equivalent GaPu4Ga8 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Superconductivity in plutonium compounds

Although the family of plutonium-based superconductors is relatively small, consisting of four compounds all of which crystallize in the tetragonal HoCoGa 5 structure, these materials serve as an important bridge between the known Ce- and U-based heavy fermion superconductors and the high-temperature cuprate superconductors. Additionally, the partial localization of 5f electrons that characterizes the novel electronic properties of elemental plutonium appears to be central to the relatively high superconducting transition temperatures that are observed in PuCoGa 5 , PuRhGa 5 , PuCoIn 5 , and PuRhIn 5 .

36 MATERIALS SCIENCE↗