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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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At least 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
DOE OSTI2014

Solid-state actinide acid phosphites from phosphorous acid melts

The reaction of UO{sub 3} and H{sub 3}PO{sub 3} at 100 °C and subsequent reaction with dimethylformamide (DMF) produces crystals of the compound (NH{sub 2}(CH{sub 3}){sub 2})[UO{sub 2}(HPO{sub 2}OH)(HPO{sub 3})]. This compound crystallizes in space group P2{sub 1}/n and consists of layers of uranyl pentagonal bipyramids that share equatorial vertices with phosphite units, separated by dimethylammonium. In contrast, the reaction of phosphorous acid and actinide oxides at 210 °C produces a viscous syrup. Subsequent dilution in solvents and use of standard solution-state methods results in the crystallization of two polymorphs of the actinide acid phosphites An(HPO{sub 2}OH){sub 4} (An=U, Th) and of the mixed acid phosphite–phosphite U(HPO{sub 3})(HPO{sub 2}OH){sub 2}(H{sub 2}O)·2(H{sub 2}O). α- and β-An(HPO{sub 2}OH){sub 4} crystallize in space groups C2/c and P2{sub 1}/n, respectively, and comprise a three-dimensional network of An{sup 4+} cations in square antiprismatic coordination corner-sharing with protonated phosphite units, whereas U(HPO{sub 3})(HPO{sub 2}OH){sub 2}(H{sub 2}O){sub 2}·(H{sub 2}O) crystallizes in a layered structure in space group Pbca that is composed of An{sup 4+} cations in square antiprismatic coordination corner-sharing with protonated phosphites and water ligands. We discuss our findings in using solid inorganic reagents to produce a solution-workable precursor from which solid-state compounds can be crystallized. - Graphical abstract: Reaction of UO{sub 3} and H{sub 3}PO{sub 3} at 100 °C and subsequent reaction with DMF produces crystals of (NH{sub 2}(CH{sub 3}){sub 2})[UO{sub 2}(HPO{sub 2}OH)(HPO{sub 3})] with a layered structure. Reaction of phosphorous acid and actinide oxides at 210 °C produces a viscous syrup and further solution-state reactions result in the crystallization of the actinide acid phosphites An(HPO{sub 2}OH){sub 4} (An=U, Th), with a three-dimensional network structure, and the mixed acid phosphite–phosphite U(HPO{sub 3})(HPO{sub 2}OH){sub 2}(H{sub 2}O){sub 2}·(H{sub 2}O) with a layered structure. - Highlights: • U(VI), U(IV) and Th(IV) phosphites were synthesized by solution-state methods. • A new uranyl phosphite structure is based upon uranyl phosphite anionic sheets. • New U and Th phosphites have framework structures.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Neutral Uranium(VI) Sulfido Compound Isolated and Characterized for the First Time

The topic of uranium element multiple bonding has long been a subject of interest to actinide scientists. While uranyl (UO 2 2+ ) is the most common form of uranium in nature, other uranium multiple bonded species are difficult to synthesize. An important interaction that has been largely elusive for actinide chemists is uranium sulfur double bonds, known as a uranium sulfido (U=S). These linkages have particular relevance to actinide lanthanide separations, where the “softer” sulfur atom allows for the removal of certain heavy elements from others. In molecular chemistry, there are few uranium sulfidos that have been synthesized, but these compounds are all anionic which limits their utility in understanding the uranium–sulfur ouble bond. This has changed with a recent report by Justin K. Pagano (Seaborg Postdoctoral Fellow, C–IIAC), David S. J. Arney (formerly C division), Brian L. Scott (MPA-11), David E. Morris (C– IIAC), Jaqueline L. Kiplinger (C–IIAC), and Carol J. Burns (DDSTE) who have synthesized several new compounds with uranium–sulfur bonds including a neutral uranium(VI) compound with a terminal uranium sulfido ligand.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1969

Study of actinide chemistry in saturated potassium fluoride solution

Study concerning the chemistry of actinides in saturated KF solution included work with neptunium, uranium, and americium. Solubilities, absorption spectra, oxidation-reduction reactions, and solid compounds which can be produced in KF solution were examined. The information is used for preparation of various materials from salts of the actinides.

Cohen, D.↗
DOE OSTI2013

Ferromagnetic Kondo lattice CeRuSi{sub 2} with non-Fermi-liquid behavior

The structure, electronic, thermodynamic, and magnetic properties of the CeRuSi{sub 2} Kondo lattice with ferromagnetic ordering characterized by a small moment of the ground state are investigated. Anomalies in the temperature dependences of heat capacity and resistivity (unusual power or logarithmic behavior) observed in the low-temperature range indicate a non-Fermi-liquid behavior. The results are compared with those for other Ce{sub l}Ru{sub n}X{sub m} compounds and anomalous systems based on rare-earth elements and actinides that had been studied earlier.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2021

Probing electronic structure in berkelium and californium via an electron microscopy nanosampling approach

Due to their rarity and radioactive nature, comparatively little is known about the actinides, particularly those with atomic numbers higher than that of plutonium, and their compounds. In this work, we describe how transmission electron microscopy can provide comprehensive, safe, and cost-effective characterization using only single nanogram amounts of highly-radioactive, solid compounds. Chlorides of the rare elements berkelium and californium are dropcast and then converted in situ to oxides using the electron beam. The f-band occupancies are probed using electron energy loss spectroscopy and an unexpectedly weak spin-orbit-coupling is identified for berkelium. In contrast, californium follows a jj coupling scheme. These results have important implications for the chemistries of these elements and solidify the status of californium as a transitional element in the actinide series.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Mixed Metal Phosphonate- Phosphate Resins for Separation of Lanthanides from Actinides

As indicated in the previous annual report the goals of this project are to develop procedures for efficient separation of lanthanides from actinides and curium from americium. These processes are required for the nuclear fuel cycle to minimize the waste and recover the valuable actinides. The basis for our study is that we have prepared a group of compounds that are porous and favor the uptake of ions with charges 3+ and 4+ over ions of lesser charge. The general formula for these materials is M(O 3 PC 6 H 4 PO 3 ) 1-x/2 (APO 4 )x·nH 2 O: where M=Zr 4+ , Sn 4+ , A=H, Na, or K and X=O, 0.5, 0.8, 1.0, 1.33 and 1.61-3. One of our tasks is to determine which members of this group of compounds are effective in carrying out the required separations. A difficulty in obtaining this required information is that the compounds are amorphous. That is they are not crystalline, therefore we need to resort to synchrotron data to obtain structural data which will be presented in detail. This information will be provided as a separate section.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Advances in Structure Prediction of Lanthanides and Actinides with Genetic Algorithms

Computationally guided materials discovery has advanced significantly in the past two decades. Recent developments of widely available genetic algorithm-based structure prediction software in the past 10+ years has led to increased use of this methodology in the discovery and design of new materials. Owing to the computational challenges of treating f-block elements and computationally expensive methods for structure prediction, the discovery of new phases of lanthanide and actinide materials has been particularly challenging. With advancements in the development of genetic algorithms for structure prediction and the continuing improvement of high-performance computing resources, genetic algorithms provide a tractable method to find new stable phases of materials at high pressure or to search a large phase space for unknown compounds. Genetic algorithms have already been applied to the successful identification of novel lanthanide and actinide materials, as well as the prediction of unusual material properties in new phases that make promising synthetic targets.

Shields, Ashley↗
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 OSTI2017

Unusual Phase Diagram of CeOs 4 Sb 12

Filled skutterudite compounds, with the formula MT 4 X 12 , where M is an alkali metal, alkaline-earth, lanthanide, or actinide, T is Fe, Ru, or Os, and X is P, As, or Sb, display a wide variety of interesting phenomena caused by strong electron correlations [1]. Among these, the three compounds CeOs 4 Sb 12 , PrOs 4 Sb 12 , and NdOs 4 Sb 12 , formed by employing Periodic Table neighbors for M, span the range from an antiferromagnetic (AFM) semimetal (M = Ce) via a 1.85 K unconventional (quadrupolar-fluctuation mediated) superconductor (M = Pr) to a 1 K ferromagnet (FM; M = Nd). In the course of an extended study of these compounds, we uncovered an unusual phase diagram for CeOs 4 Sb 12 .

36 MATERIALS SCIENCE↗
DOE OSTI2026

Expanding the Boundaries of Transuranium Chemistry

During the last several Heavy Elements Chemistry grant cycles under award(s): DE-FG02-13ER16414, we have published nearly 90 research articles (see bibliography) in 25 peer-reviewed journals. Additionally, this funding has resulted in several review articles. Together, these publications have already reached well over 4500 citations. These research articles have introduced several hundreds of new crystallographically authenticated f-element compounds and materials and have greatly affected the field of Heavy Elements Chemistry. Concentrating on the heaviest elements that can be studied on the milligram scale, the transplutonium elements are the focus of nearly 30 of these manuscripts containing results such as the first single crystal structure of a berkelium compound and californium presenting itself as an additional transition point in the actinide series.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2020

EFRC Materials Science of Actinides (Final Report)

The Energy Frontier Research Center Materials Science of Actinides (MSA) conducted basic research from 2009-2019. The scientific personnel and participating institutes changed several times during the evolution of the Center, and in total included 24 senior investigators, four national laboratories, and ten universities. Workforce development was a motivating goal of the university-led Center, which included many undergraduate, graduate, and post-doctoral researchers. The center focused on the actinide elements, which arise from the sequential filling of the 5f electron orbitals. Although the specific themes evolved during the Center’s history, the final research themes were: (1) Nanoscale Cage Clusters, (2) Complex Ceramic and Metallic Materials, and (3) Materials Under Extreme Environments. To date, the Center has produced 254 peer-reviewed journal publications and book chapters that acknowledged only the EFRC funding, and an additional 161 journal publications and book chapters that acknowledged funding from the EFRC and additional sources (a few manuscripts are still in preparation). Broad highlights include: (1) Development of an extensive family of actinide nanomaterials that self-assemble in aqueous solution, an understanding of their formation mechanisms and stabilities, and possible uses in nuclear fuel cycles; (2) Establishment of facilities and methodologies to conduct high-temperature calorimetry on transuranium materials, and extensive thermodynamic-based studies of uranium and thorium compounds important to the nuclear fuel cycle; (3) A vastly improved understanding of the behavior of actinide materials in extreme conditions, including high radiation fields, temperatures, and pressures, as well coupled effects of two or more of these; (4) Development of resonance ultrasound spectroscopy and direct measurement of aging of plutonium alloys.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Actinide complexes with Wells–Dawson polyoxometalates (part 2): californium

We report the first example of a polyoxometalate (POM) compound containing californium. Using a Wells–Dawson POM ligand, K 17 Cf(P 2 W 17 O 61 ) 2 ·2H 2 O was synthesized and characterized. Californium is the heaviest element ever crystalized with a POM. Significant solubility differences among the POM's f-element complexes were observed, enabling selective precipitation with separation factors rivaling liquid–liquid extraction.

and nuclear chemistry↗
DOE OSTI2022

Probing f-orbital covalency through the fold angles of transuranium dithiolene complexes

The ability of the actinide elements to covalently bond to ligands is not well understood. A computational effort for compounds of the formula [Cp 2 AnS 2 C 2 H 2 ] -1,0,+1 where An = U, Np, or Pu has shown that the angle between the plane formed by the two sulfurs and the plane formed by the two sulfur atoms and the two carbons converges to 70 – 75° when the ligand is in the dithiolate state (-2 charge on the ligand). Upon oxidation of [Cp 2 NpS 2 C 2 H 2 ] 0 or [Cp 2 PuS 2 C 2 H 2 ] 0 the electron is removed from the dithiolate rather than the actinide and the dihedral angle is reduced to planarity. The reaction of NpCl 4 DME 2 with deprotonated benzene dithiol shows an intense color change suggestive of a charge transfer complex. The binding of the benzene dithiol as the dithiolate to the neptunium metal center is supported by visible, infrared and NMR spectroscopies.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

A novel cage for actinides: A 6 W 4 Al 43 ( A = U and Pu)

We report on synthesis and characterization of the compounds A 6 W 4 Al 43 ( A = U and Pu), that form in the hexagonal Ho 6 Mo 4 Al 43 caged-structure family. The A ions reside within W/Al cages where the A – A nearest neighbors form dimers between adjacent W/Al cages, with U–U and Pu–Pu distances of 3.3892 and 3.4080 , respectively. While the W/Al networks provide environments similar to those of other cage-like materials (e.g. filled skutterudites), the atomic displacement parameters from single crystal x-ray diffraction measurements show that the A -ions do not exhibit rattling behavior. We find that there is site interchange disorder on one of the W/Al sites. Magnetic susceptibility measurements show that U 6 W 4 Al 43 displays anisotropic Curie–Weiss behavior where it fits to the data yield an effective magnetic moment near 2.0 /U. At low temperatures the magnetic susceptibility deviates from the Curie–Weiss temperature dependence and eventually saturates to a constant value. In contrast, Pu 6 W 4 Al 43 displays nearly temperature independent Pauli paramagnetism for all temperatures, as would be expected if the 5 f -electrons are delocalized. The electrical resistivity for U 6 W 4 Al 43 increases slightly with the decreasing temperature, suggesting that it is dominated by f -electronic hybridization effects and disorder scattering that originates from the W/Al site interchange. Specific heat measurements for U 6 W 4 Al 43 further reveal an enhanced electronic Sommerfeld coefficient that is consistent with a moderately enhanced charge carrier effective mass. Together these measurements expose these materials as hosts for unstable f -electron magnetism, where the novel cage-like structures control the phenomena through the spacing between the A ions. Through this combination of mild magnetism, the low cost elements of the Al–W cages, and chemical tunability that has been shown for related materials in the same structure, the A 6 W 4 Al 43 compounds emerge as promising nuclear waste-forms for transuranics, while the wider family of materials makes an appealing environment for studying f

charge transport↗
DOE OSTI2016

The CCONE Code System and its Application to Nuclear Data Evaluation for Fission and Other Reactions

A computer code system, CCONE, was developed for nuclear data evaluation within the JENDL project. The CCONE code system integrates various nuclear reaction models needed to describe nucleon, light charged nuclei up to alpha-particle and photon induced reactions. The code is written in the C++ programming language using an object-oriented technology. At first, it was applied to neutron-induced reaction data on actinides, which were compiled into JENDL Actinide File 2008 and JENDL-4.0. It has been extensively used in various nuclear data evaluations for both actinide and non-actinide nuclei. The CCONE code has been upgraded to nuclear data evaluation at higher incident energies for neutron-, proton-, and photon-induced reactions. It was also used for estimating β-delayed neutron emission. This paper describes the CCONE code system indicating the concept and design of coding and inputs. Details of the formulation for modelings of the direct, pre-equilibrium and compound reactions are presented. Applications to the nuclear data evaluations such as neutron-induced reactions on actinides and medium-heavy nuclei, high-energy nucleon-induced reactions, photonuclear reaction and β-delayed neutron emission are mentioned.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2021

The coordination properties and ionic radius of actinium: A 120-year-old enigma

Actinium is an elusive element with untamed properties and represents a peculiar case in the periodic table, as its isotopes are all radioactive, the longest-lived one having only a 22-year half-life, and the availability of actinium isotopes remains very low (microgram level, at best), hindering research on its compounds. Despite being a natural element discovered more than 120 years ago, and despite an increasing interest in using one of its isotopes ( 225 Ac) for highly efficient cancer therapies, the chemistry of actinium is still largely unknown relative to other elements. Since Ac is the first element of the actinide series, it is accepted that its ion, Ac 3+ , is the most voluminous trivalent cation of the periodic table. However, the structural data available on Ac 3+ compounds are scarce and have mainly been collected in the 1940-1960's, when actinide chemistry was still in its infancy, and have not been put in perspective with the advances in the chemistry of other elements, making it difficult to accurately evaluate its actual size and coordination chemistry. Here, we review progress made on the chemistry of lanthanides and actinides and reevaluate the structural data published on Ac 3+ since the era of the Manhattan Project. The data are combined across different spectroscopic and characterization methods and presented in the context of periodic trends. When considering crystallographic data, solution chemistry results, and the nuclear properties of actinium isotopes, it appears that some structural parameters ascribed to the Ac 3+ ion may have been overestimated. This review can guide researchers interested in actinide sciences and those who are pursuing the development of actinium-based radiotherapies, from isotope production to clinical trials.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Quantum chemical topology and natural bond orbital analysis of M–O covalency in M(OC 6 H 5 ) 4 (M = Ti, Zr, Hf, Ce, Th, Pa, U, Np)

Covalency is complex yet central to our understanding of chemical bonding, particularly in the actinide series. In this work, we assess covalency in a series of isostructural d and f transition element compounds M(OC 6 H 5 ) 4 (M = Ti, Zr, Hf, Ce, Th, Pa, U, Np) using scalar relativistic hybrid density functional theory in conjunction with the Natural Bond Orbital (NBO), quantum theory of atoms in molecules (QTAIM) and interacting quantum atoms (IQA) approaches. The IQA exchange–correlation covalency metric is evaluated for the first time for actinides other than uranium, in order to assess its applicability in the 5f series. It is found to have excellent correlation with NBO and QTAIM covalency metrics, making it a promising addition to the computational toolkit for analysing metal–ligand bonding. Our range of metrics agree that the actinide-oxygen bonds are the most covalent of the elements studied, with those of the heavier group 4 elements the least. Within the early actinide series, Th stands apart from the other three elements considered, being consistently the least covalent.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2014

Investigating Enhanced Thorium Ionization in TIMS Using Re/Pt Porous Ion Emitters

Thermal ionization mass spectrometry (TIMS) is a widely used, benchmark method in the isotopic analysis of actinides relevant to various nuclear and geological fields. Despite significant previous use and inherent advantages, however, poor sample ionization continues to hamper the use of TIMS in the measurement of trace species; actinide ionization efficiencies frequently fall below 0.1 % using traditional instrument sources. Factors leading to poor ionization are compounded in the measurement of several highly refractory metals (e.g. U and Th) that may provide key signatures data in non-proliferation, safeguards and forensics efforts. Herein, a relatively new TIMS ion source strategy, employing porous ion emitters (PIEs) atop traditional filament assemblies, is investigated for the first time as a straightforward means of enhancing the ionization of Th, which is arguably a worst case scenario for TIMS-based actinide measurements. These sources yielded up to 410% greater Th sample utilization, relative to previously published values and in-house measurements collected using traditional methods. Accompanying scanning electron microscopy (SEM) investigations provide preliminary insight into possible mechanisms of PIE functioning and explore the impacts that extended heating have on the constructed source’s structure and composition.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗