High-pressure studies of americium metal: Insights into its position in the actinide series

Lindbaum, A.; Heathman, S.; Litfin, K.; Méresse, Y.; Haire, R.G.; Bihan, T. Le; Libotte, H.

doi:10.1103/physrevb.63.214101

Cited by 96 publications

(113 citation statements)

References 28 publications

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“…Consequently, the canonical-band picture predicts a p.o phase in Am at high pressure. This has indeed been established recently in diamond-anvil-cell work at 16 GPa [45].…”

Section: Now When We Have Confidently Established That Photoemission mentioning

confidence: 72%

On the electronic configuration in Pu: spectroscopy and theory

Tobin

Söderlind

Landa

et al. 2008

J. Phys.: Condens. Matter

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Photoelectron spectroscopy, synchrotron-radiation-based x-ray absorption, electron energy loss spectroscopy, and density-functional calculations within the mixed-level and magnetic models, together with canonical band theory, have been used to study the electron configuration in Pu. These methods suggest a 5f n occupation for Pu of 5 n < 6, with n = 6, contrary to what has recently been suggested in several publications. We show that the n = 6 picture is inconsistent with the usual interpretation of photoemission, x-ray absorption, and electron energy loss spectra. Instead, these spectra support the traditional conjecture of a 5f 5 occupation in Pu as is obtained by density-functional theory. We further argue, based on 5f-band filling, that an n = 6 hypothesis is incompatible with the position of Pu in the actinide series and its monoclinic ground-state phase.

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“…Consequently, the canonical-band picture predicts a p.o phase in Am at high pressure. This has indeed been established recently in diamond-anvil-cell work at 16 GPa [45].…”

Section: Now When We Have Confidently Established That Photoemission mentioning

confidence: 72%

On the electronic configuration in Pu: spectroscopy and theory

Tobin

Söderlind

Landa

et al. 2008

J. Phys.: Condens. Matter

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“…1), indicating that each phase has a comparable bulk modulus. This same transition occurs in Am, but at a lower pressure (6 GPa) (8,9).…”

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confidence: 83%

“…In Am, the total collapse of È9% for two transitions is smaller than that for Cm, but in both elements the collapses occur in two stages. The appearance of the Fddd and Pnma forms for Am (8,9) and Cm at higher pressures is a clear indication that the 5f delocalization process favors these structures. The puzzle, however, remains the formation of the Cm III phase.…”

mentioning

confidence: 90%

“…Under compression, the relative volume changes with pressure for a-uranium (the room-temperature-stable form of uranium metal) (7) are clearly different from those for either Am or curium (Cm). We have investigated in detail the case of Am (8,9), where four crystal structures are found to exist between ambient pressure and 100 GPa. The delocalization of the 5f electrons of Am by pressure occurs in two stages, with the progressive formation of two lower symmetry structures, a face-centered orthorhombic Am III and a primitive orthorhombic structure, Am IV; the transition to each is accompanied by an abrupt decrease in the relative atomic volume.…”

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confidence: 99%

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A High-Pressure Structure in Curium Linked to Magnetism

Heathman

Haire

Bihan

et al. 2005

Science

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121

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Curium lies at the center of the actinide series and has a half-filled shell with seven 5f electrons spatially residing inside its radon core. As a function of pressure, curium exhibits five different crystallographic phases up to 100 gigapascals, of which all but one are also found in the preceding element, americium. We describe here a structure in curium, Cm III, with monoclinic symmetry, space group C2/c, found at intermediate pressures (between 37 and 56 gigapascals). Ab initio electronic structure calculations agree with the observed sequence of structures and establish that it is the spin polarization of curium's 5f electrons that stabilizes Cm III. The results reveal that curium is one of a few elements that has a lattice structure stabilized by magnetism.

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“…Previous studies on these elements from americium 4,5 to curium 6 have shown a remarkable diversity of crystallographic structures which appear under pressure due to the influence of this 5f electron participation. Atomic volumes are also affected by 5f electron bonding across the actinide series with smaller volumes observed in the Pa to Pu metals which result from additional 5f bonding already being present at ambient pressure.…”

Section: Introductionmentioning

confidence: 99%

Structural investigation of californium under pressure

et al. 2013

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The high pressure structural behaviour of californium has been studied experimentally and theoretically up to 100 GPa. A valence change from divalent to trivalent forms was observed under modest pressure revealing californium to be the only actinide to exhibit more than one metallic valence at near to ambient conditions as is the case for cerium in the lanthanide series. 3 metallic valencies and 4 different crystallographic phases were observed in californium as a function of pressure. High-pressure techniques, synchrotron radiation and ab initio electronic structure calculations of total energies were used to investigate the material and to determine the role which californiums 5f electrons play in influencing these transitions.The crystallographic structures observed are similar to those found in the preceding actinide elements, curium and americium with the initially localized 5f states becoming completely delocalized under the influence of high pressure.

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High-pressure studies of americium metal: Insights into its position in the actinide series

Cited by 96 publications

References 28 publications

On the electronic configuration in Pu: spectroscopy and theory

On the electronic configuration in Pu: spectroscopy and theory

A High-Pressure Structure in Curium Linked to Magnetism

Structural investigation of californium under pressure

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