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At least 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

X-ray Crystal Structure of Thorium Tetrahydroborate, Th(BH 4 ) 4 , and Computational Studies of An(BH 4 ) 4 (An = Th, U)

Here the crystal structure of Th(BH 4 ) 4 is described. Two of the four BH 4 – ions are terminal and tridentate (κ 3 ), whereas the other two bridge between neighboring Th IV centers in a κ 2 ,κ 2 (i.e., bis-bidentate) fashion. Thus, each thorium center is bound to six BH 4 – groups by 14 Th–H bonds. The six boron atoms describe a distorted octahedron in which the κ 3 -BH 4 – ions are mutually cis; the 14 ligating hydrogen atoms define a highly distorted bicapped hexagonal antiprism. The thorium centers are linked into a polymer consisting of interconnected helical chains wound about 4-fold screw axes. The structures of An(BH 4 ) 4 (An = Th, U) were also investigated by DFT. The geometries of [An(BH 4 ) 6 ] 2– , [An3(BH 4 ) 16 ] 4– , and [An 5 (BH 4 ) 26 ] 6– fragments of the polymeric structures were optimized at the B3LYP and/or PBE levels. Most calculated geometries are 14-coordinate and agree with the experimental structures, but isolated [Th(BH 4 ) 6 ] 2– units are predicted to feature 16-coordinate Th IV centers.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Novel methods for TH-229 production through fast neutron irradiation of TH-23F0 and charged particle irradiation of Th-230 and Th-232. Final Report DE-SC0020140

The activities and results of research related to accelerator production of Pa and Th isotopes via bombardment of 230 Th and 232 Th targets are described herein. This research was supported through DOE grant DE-SC0020140 and was conducted in collaboration with Oak Ridge National Laboratory and Lawrence Berkeley National Laboratory. Cross section measurements, transport model and nuclear physics model calculations are presented. Highlights include the first ever measurements of 229 Pa, two publications, and graduation of a PhD student.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2020

Th 2 O – , Th 2 Au – , and Th 2 AuO 1,2 – Anions: Photoelectron Spectroscopic and Computational Characterization of Energetics and Bonding

The observation and characterization of the anions: Th 2 O – , Th 2 Au – , and Th 2 AuO 1,2 – is reported. These species were studied through a synergetic combination of anion photoelectron spectroscopy and ab initio correlated molecular orbital theory calculations at the CCSD(T) level with large correlation-consistent basis sets. To better understand the energetics and bonding in these anions and their corresponding neutrals, a range of smaller diatomic to tetratomic species were studied computationally. Correlated molecular orbital theory calculations at the CCSD(T) level showed that in most of these cases, there are close-lying anions and neutral clusters with different geometries and spin states and are consistent with the experimentally observed spectra. Thus, comparison of experimentally determined and computationally predicted vertical detachment energies and electron affinities for different optimized geometries and spin states shows excellent agreement to within 0.1 eV. The structures for both the neutrals and anions have a significant ionic component to the bonding because of the large electron affinity of the Au atom and modest ionization potentials for Th 2 , Th 2 O, and Th 2 O 2 . The analysis of the bonding for the Th–Th bonds from the molecular orbitals is consistent with this ionic model. The results show that there is a wide variation in the bond distance from 2.7 to 3.5 Å for the Th–Th bonds all of which are less than twice the atomic radius of Th of 3.6 Å. The bond distances encompass bond orders from 4 to 0. Furthermore, there can be different bond orders for the same bond distance depending on the nature of the ionic bonding suggesting that one may not be able to correlate the bond order with the bond distance in these types of clusters. In addition, the presence of an Au atom may provide a unique probe of the bonding in such clusters because of its ability to accept an electron from clusters with modest ionization potentials.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Anion-induced disproportionation of Th( iii ) complexes to form Th( ii ) and Th( iv ) products

Here, a new synthesis of Th(II) complexes has been identified involving addition of simple MX salts (M = Li, Na, K; X = H, Cl, Me, N 3 ) to Cp" 3 Th III [Cp" = [C 5 H 3 (SiMe 3 ) 2 ] in the presence of 18-crown-6 or 2.2.2-cryptand, forming [M(chelate)][Cp" 3 Th II ] and Cp'' 3 Th IV X. Cp tet 3 Th III (Cp tet = C 5 Me 4 H) reacts with KH to form Cp tet 3 Th IV H and the C–H bond activation product, [K(crypt)]{[Cp tet 2 Th IV H[η 1 :η 5 -C 5 Me 3 H(CH 2 )]}.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Measurement of the 230 Th( p ,2n)Pa229 and 230 Th( p ,3n)Pa228 reaction cross sections from 14.1 to 16.9 MeV

Actinium-225 is of interest for medical isotope production and there is on-going research into methods of producing Ac 225 , either directly or via the decay of its parent isotopes ( Th 229 , Pa 229 , and Ra 225 ). One method that has been suggested is the Th 230 ( p , 2 n ) Pa 229 reaction. However, there is no available cross-section data for this reaction in the literature. Purpose: Measure the Th 230 ( p , 2 n ) and Th 230 ( p , 3 n ) reaction cross sections in the energy range where the ( p , 2 n ) reaction is predicted to peak to determine the feasibility of Ac 225 production via the Th 230 ( p , 2 n ) reaction. Methods: Targets naturally enriched in Th 230 were irradiated at the Center for Accelerator Mass Spectrometry at Lawrence Livermore National Laboratory with energies ranging from 14.1 to 16.9 MeV. Furthermore, chemical processing was used to separate the protactinium activation products, followed by γ -ray spectroscopy to measure the activities of Pa 228 , 229 , 230 , 232 produced in the irradiation. Results: We find that excitation functions are reported for the first time in the literature for the Th 230 ( p , 2 n ) and Th 230 ( p , 3 n ) reactions in this energy range. The peak measured value of the Th 230 ( p , 2 n ) reaction was found to be 182 ± 12 mb at 14.4 ± 0.1 MeV. The Th 232 ( p , n ) Pa 232 reaction was used to verify the experimental conditions, the measured values are reported and are comparable to the existing literature values. From the γ -ray spectrometry data, the half-life of Pa 229 was measured as 1.5 ± 0.1 days, which is within the error of the half-life reported in the evaluated nuclear data as well as in the recent measurements, and the half-life of Pa 228 was measured as 19.5 ± 0.4 hours. Conclusions: Overall, the Th 230 ( p , 2 n ) Pa 229 reaction could reasonably be used for Ac 225 isotope production, although significant amounts of relatively isotopically pure Th 230 would be needed for significant production because the low alpha-decay branching ratio of Pa 229 and long half-life of Th 229 inhibit the in-growth of significant amounts of Ac 225 .

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2021

Effect of Background Electrolyte Composition on the Interfacial Formation of Th(IV) Nanoparticles on the Muscovite (001) Basal Plane

Understanding the impact of actinide nanoparticle (NP) formation is important to assess radionuclide mobility in the environment. We combined surface X-ray diffraction (SXRD) and in situ AFM to investigate the previously reported unusual electrolyte effects on Th uptake on mica. At low [Th] (0.1 mM), interfacial structures show a broad Th electron density (~50 Å). A linear decrease of Th uptake with decreasing hydration enthalpy of the electrolyte cation (Li+, K+, NH4+, and Cs+) indicates a competitive effect between Th and the electrolyte cation. Na+ is a clear outlier from this trend. In situ AFM imaging confirms the results. Particles show a vertical size of ~1–2 nm and larger lateral dimensions of ~10–20 nm, which is typical for particles formed at interfaces (heterogeneous nucleation). At high [Th] = 1 and 3 mM, all investigated electrolytes (ACl, A = Li+, Na+, K+) show similar Th uptake, indicating a much smaller impact of electrolyte composition. The interfacial structures are dominated by a high Th loading at a distinct distance (~6.5 Å) from the surface. Therefore, the main retention mechanism at high [Th] is suggested to be the sorption of Th NPs aggregated from Th oligomers present in solution (homogeneous nucleation).

Neumann, J↗
DOE OSTI2020

Electronic Structures and Magnetism of Zr-, Th-, and U-based Metal-Organic Frameworks (MOFs) by Density Functional Theory

Metal-organic frameworks (MOFs) have recently gained wide interest as candidate materials for nuclear waste immobilization. While the fundamental thermodynamic properties, such as the substitution energies determine the favorability of radionuclide sequestration by utilization of a MOF matrix, the studies of MOF electronic structure reveal the role of d-, and/or f-electrons on changes in physical properties of actinide-containing materials. We use density functional theory (DFT) calculations to investigate the electronic structures of Zr-, Th-, and U-MOFs, including their electronic band structures and, where appropriate, their magnetic properties. We employ various DFT methods including DFT+U, collinear spin-polarization, spin-orbit coupling, and different flavors of exchange-correlation functionals to assess the robustness to the specific exchange-correlation functional. Unlike the Zr-, and Th-MOFs, the U-MOF is found to be sensitive to electron localization and spin; hence we explore the magnetic structure of the U-MOF in further detail.

Metal-Organic Framework, MOF, Actinides, DFT↗
DOE OSTI2020

Data Evaluation of Actinide Cross Sections: 230 Th and 231 Th

A new evaluation of the ENDL cross section set for Thorium (Z=90) is developed using the TALYS statistical model cross section code. The primary goal of this effort is to produce an evaluation that attempts to match as closely as possible fission cross sections developed through surrogate reaction techniques on actinide targets 230 Th and 231 Th. This evaluation effort and the processing needed to render its results into data libraries is a necessary step in making the efforts of nuclear experimentalists useful to the broad community of researchers engaged in simulations of nuclear fusion for basic and applied science. Another aspect, verification and validation against various AGEX experiments, is also presented. The end-product is an updated library that includes the latest measurements of fission cross sections for comparison against those measured via traditional techniques. All the steps in the evaluation, processing, validation and verification, and library release are described in the following sections. For completeness, the appendix contains all the parameters used in the TALYS cross section evaluation for neutrons incident on 230 Th and 231 Th.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2023

Elucidating Actinide–Pertechnetate and Actinide–Perrhenate Bonding via a Family of Th–TcO 4 and Th–ReO 4 Frameworks and Solutions

Technetium-99, a β-emitter produced from 235 U fission, poses a challenge for the nuclear industry due to co-extraction of pertechnetate (TcO 4 – ) with the actinides (An) during nuclear fuel reprocessing. Previous studies suggested that direct coordination of pertechnetate with An plays an important role in the coextraction process. However, few studies have provided direct evidence for An–TcO 4 – bonding in the solid state, and even fewer in solution. The present study describes synthesis and structural elucidation of a family of thorium(IV)-pertechnetate/perrhenate (ReO 4 – , nonradioactive surrogate) compounds, which is obtained by dissolution of thorium oxyhydroxide in perrhenic/pertechnic acid followed by crystallization, with or without heating. For reaction ratios of 3:1, 4:1, and 6:1 MO 4 – /Th(IV) (M = Tc, Re), the crystallized compounds reflect the same ratio, suggesting facile and flexible coordination. Furthermore, nine structures reveal 1-dimensional and 2-dimensional frameworks with varying topologies. While a multitude of compounds isolated from 4:1 (and 6:1) reaction solutions feature Th monomers linked by MO 4 – , the 3:1 reaction solution yielded the well-known dihydroxide-bridged thorium dimer, linked, and capped by MO 4 – . Density functional theory calculations on ReO 4 – /TcO 4 – isomorphs suggest similar bonding characteristics in the solid state, but experimental solution characterization noted differences. Specifically, small-angle X-ray scattering studies suggest the bonding of Th–TcO 4 – persists in solution, while Th–ReO 4 – bonding is less apparent.

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

Using molecular dynamics to predict the solidus and liquidus of mixed oxides ( Th , U ) O 2 , ( Th , Pu ) O 2 and ( Pu , U ) O 2

Molecular dynamics (MD) was used to establish a mechanistic basis for the experimentally observed reduction in liquidus and solidus temperatures below the melting point of the end-members for the mixed oxides (Th,U)O 2 , (Th, Pu) O 2 and (Pu, U) O 2 . This dip is found at additions of the oxide with higher melting point to the oxide with the lower melting point. There are many causes suggested for the dip; here the distribution of the cation Frenkel energy for the mixed oxides caused by the local environment is proposed as a contributor. Furthermore, a variant of the moving interface method which yields information on the position of the solidus and liquidus boundaries, is used to predict the phase diagrams of these systems.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Th(SO8)2 by Materials Project

Th(SO7)2O2 crystallizes in the monoclinic P2_1/c space group. The structure is zero-dimensional and consists of four oxygen molecules and four Th(SO7)2 clusters. In each Th(SO7)2 cluster, Th is bonded in a 9-coordinate geometry to nine O atoms. There are a spread of Th–O bond distances ranging from 2.24–2.94 Å. There are two inequivalent S sites. In the first S site, S is bonded in a tetrahedral geometry to four O atoms. There are a spread of S–O bond distances ranging from 1.44–1.57 Å. In the second S site, S is bonded in a tetrahedral geometry to four O atoms. There are a spread of S–O bond distances ranging from 1.44–1.58 Å. There are fourteen inequivalent O sites. In the first O site, O is bonded in a water-like geometry to one Th and one S atom. In the second O site, O is bonded in a bent 120 degrees geometry to one Th and one O atom. The O–O bond length is 1.23 Å. In the third O site, O is bonded in a water-like geometry to one Th and one S atom. In the fourth O site, O is bonded in a distorted single-bond geometry to one Th and one O atom. The O–O bond length is 1.25 Å. In the fifth O site, O is bonded in a single-bond geometry to one S atom. In the sixth O site, O is bonded in a single-bond geometry to one S atom. In the seventh O site, O is bonded in a single-bond geometry to one S atom. In the eighth O site, O is bonded in a single-bond geometry to one S atom. In the ninth O site, O is bonded in a single-bond geometry to one O atom. In the tenth O site, O is bonded in a water-like geometry to one Th and one S atom. In the eleventh O site, O is bonded in an L-shaped geometry to one Th and one O atom. The O–O bond length is 1.25 Å. In the twelfth O site, O is bonded in a 1-coordinate geometry to one Th and one O atom. In the thirteenth O site, O is bonded in a 1-coordinate geometry to one Th and one O atom. In the fourteenth O site, O is bonded in a water-like geometry to one Th and one S atom.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Evaluation of Candidate Theranostics for 227 Th/ 89 Zr Paired Radioimmunotherapy of Lymphoma

227 Th is a promising radioisotope for targeted α-particle therapy. It produces 5 α-particles through its decay, with the clinically approved 223 Ra as its first daughter. There is an ample supply of 227 Th, allowing for clinical use; however, the chemical challenges of chelating this large tetravalent f-block cation are considerable. Using the CD20-targeting antibody ofatumumab, we evaluated chelation of 227 Th 4+ for α-particle–emitting and radiotheranostic applications. Methods: We compared 4 bifunctional chelators for thorium radiopharmaceutical preparation: S-2-(4-Isothiocyanatobenzyl)-1,4,7,10-tetraazacyclododecane tetraacetic acid (p-SCN-Bn-DOTA), 2-(4-isothicyanatobenzyl)-1,2,7,10,13-hexaazacyclooctadecane-1,4,7,10,13,16-hexaacetic acid (p-SCN-Bn-HEHA), p-isothiacyanatophenyl-1-hydroxy-2-oxopiperidine-desferrioxamine (DFOcyclo*-p-Phe-NCS), and macrocyclic 1,2-HOPO N-hydroxysuccinimide (L804-NHS). Immunoconstructs were evaluated for yield, purity, and stability in vitro and in vivo. Tumor targeting of the lead 227 Th-labeled compound in vivo was performed in CD20-expressing models and compared with a companion 89 Zr-labeled PET agent. Results: 227 Th-labeled ofatumumab-chelator constructs were synthesized to a radiochemical purity of more than 95%, excepting HEHA. 227 Th-HEHA-ofatumumab showed moderate in vitro stability. 227 Th-DFOcyclo*-ofatumumab presented excellent 227 Th labeling efficiency; however, high liver and spleen uptake was revealed in vivo, indicative of aggregation. 227 Th-DOTA-ofatumumab labeled poorly, yielding no more than 5%, with low specific activity (0.08 GBq/g) and modest long-term in vitro stability (<80%). 227 Th-L804-ofatumumab coordinated 227 Th rapidly and efficiently at high yields, purity, and specific activity (8 GBq/g) and demonstrated extended stability. In vivo tumor targeting confirmed the utility of this chelator, and the diagnostic analog, 89 Zr-L804-ofatumumab, showed organ distribution matching that of 227 Th to delineate SU-DHL-6 tumors. Conclusion: Commercially available and novel chelators for 227 Th showed a range of performances. The L804 chelator can be used with potent radiotheranostic capabilities for 89 Zr/ 227 Th quantitative imaging and α-particle therapy.

227Th↗
DOE OSTI2020

Materials Data on Th(Re2Si)2 by Materials Project

Th(Re2Si)2 crystallizes in the orthorhombic Pnnm space group. The structure is three-dimensional. Th is bonded in a 7-coordinate geometry to ten Re and seven Si atoms. There are a spread of Th–Re bond distances ranging from 3.29–3.52 Å. There are a spread of Th–Si bond distances ranging from 3.12–3.18 Å. There are four inequivalent Re sites. In the first Re site, Re is bonded in a 12-coordinate geometry to two equivalent Th, eight Re, and two equivalent Si atoms. There are a spread of Re–Re bond distances ranging from 2.62–2.98 Å. Both Re–Si bond lengths are 2.52 Å. In the second Re site, Re is bonded in a 12-coordinate geometry to three equivalent Th, six Re, and three Si atoms. There are a spread of Re–Re bond distances ranging from 2.61–2.77 Å. There are one shorter (2.49 Å) and two longer (2.60 Å) Re–Si bond lengths. In the third Re site, Re is bonded in a 12-coordinate geometry to two equivalent Th, eight Re, and three Si atoms. There are one shorter (2.73 Å) and two longer (2.90 Å) Re–Re bond lengths. There are a spread of Re–Si bond distances ranging from 2.48–3.04 Å. In the fourth Re site, Re is bonded to three equivalent Th, six Re, and three equivalent Si atoms to form distorted face-sharing ReTh3Re6Si3 cuboctahedra. There are one shorter (2.46 Å) and two longer (2.54 Å) Re–Si bond lengths. There are two inequivalent Si sites. In the first Si site, Si is bonded in a 9-coordinate geometry to four equivalent Th, five Re, and one Si atom. The Si–Si bond length is 2.61 Å. In the second Si site, Si is bonded in a 9-coordinate geometry to three equivalent Th and six Re atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Th(GeRu)2 by Materials Project

Th(RuGe)2 crystallizes in the triclinic P1 space group. The structure is three-dimensional. Th is bonded in a 12-coordinate geometry to eight Ru and eight Ge atoms. There are a spread of Th–Ru bond distances ranging from 3.29–3.31 Å. There are a spread of Th–Ge bond distances ranging from 3.29–3.34 Å. There are two inequivalent Ru sites. In the first Ru site, Ru is bonded in a 4-coordinate geometry to four equivalent Th and four Ge atoms. There are two shorter (2.46 Å) and two longer (2.47 Å) Ru–Ge bond lengths. In the second Ru site, Ru is bonded in a 4-coordinate geometry to four equivalent Th and four Ge atoms. There are three shorter (2.46 Å) and one longer (2.47 Å) Ru–Ge bond lengths. There are two inequivalent Ge sites. In the first Ge site, Ge is bonded in a 9-coordinate geometry to four equivalent Th, four Ru, and one Ge atom. The Ge–Ge bond length is 2.61 Å. In the second Ge site, Ge is bonded in a 9-coordinate geometry to four equivalent Th, four Ru, and one Ge atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Th(CuSn)2 by Materials Project

Th(CuSn)2 crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Th is bonded in a 12-coordinate geometry to eight Cu and eight Sn atoms. There are four shorter (3.37 Å) and four longer (3.43 Å) Th–Cu bond lengths. There are four shorter (3.37 Å) and four longer (3.55 Å) Th–Sn bond lengths. There are two inequivalent Cu sites. In the first Cu site, Cu is bonded in a 12-coordinate geometry to four equivalent Th and four equivalent Sn atoms. All Cu–Sn bond lengths are 2.61 Å. In the second Cu site, Cu is bonded in a 9-coordinate geometry to four equivalent Th and five Sn atoms. There are one shorter (2.50 Å) and four longer (2.65 Å) Cu–Sn bond lengths. There are two inequivalent Sn sites. In the first Sn site, Sn is bonded in a 9-coordinate geometry to four equivalent Th and five Cu atoms. In the second Sn site, Sn is bonded in a 4-coordinate geometry to four equivalent Th and four equivalent Cu atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Th(NiSn)2 by Materials Project

Th(NiSn)2 crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Th is bonded in a 8-coordinate geometry to eight Ni and eight Sn atoms. There are four shorter (3.25 Å) and four longer (3.44 Å) Th–Ni bond lengths. There are four shorter (3.33 Å) and four longer (3.49 Å) Th–Sn bond lengths. There are two inequivalent Ni sites. In the first Ni site, Ni is bonded in a 8-coordinate geometry to four equivalent Th and four equivalent Sn atoms. All Ni–Sn bond lengths are 2.56 Å. In the second Ni site, Ni is bonded in a 9-coordinate geometry to four equivalent Th and five Sn atoms. There are one shorter (2.49 Å) and four longer (2.57 Å) Ni–Sn bond lengths. There are two inequivalent Sn sites. In the first Sn site, Sn is bonded in a 9-coordinate geometry to four equivalent Th and five Ni atoms. In the second Sn site, Sn is bonded in a 4-coordinate geometry to four equivalent Th and four equivalent Ni atoms.

36 MATERIALS SCIENCE↗