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At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Irradiation Driven Restructuring of Nanocrystalline ThO 2 and Th 1–x U x O 2 Thin Films

Irradiation induced structural changes of actinide oxide materials is a key consideration in their development and use as nuclear fuels. This study reported on the synthesis of ThO 2 and Th 1–x U x O 2 (x = 0.15, 0.50) thin films, fabricated using electrospray-assisted solution combustion synthesis, and their responses to ion irradiation. Krypton ion irradiations, up to a fluence of 1 × 10 16 ions/cm 2 , were carried out to simulate radiation damage induced by fission products in a reactor environment. Structural and chemical changes induced by irradiation were analyzed using high-resolution scanning transmission electron microscopy (STEM), energy-dispersive X-ray spectroscopy (EDS), and electron energy-loss spectroscopy (EELS). It was determined that the extent and nature of irradiation-induced damage are strongly correlated with the uranium content. ThO 2 films were most susceptible to radiation-induced damage, with significant cavity formation and delamination from the substrate at high fluence. Of the compositions studied, Th 0.85 U 0.15 O 2 films showed the highest stability, characterized by moderate grain growth and the absence of voids or severe defect structures. In contrast, Th 0.5 U 0.5 O 2 films accumulated extensive damage, including the formation of a nanocrystalline central region. EELS analysis indicated that oxygen displacement is the primary driver of structural degradation in Th 0.5 U 0.5 O 2 films. α-particle spectroscopy confirmed minimal actinide loss across all compositions, underscoring the mechanical robustness of the films. These findings provide insight into the irradiation-induced damage mechanisms in Th O2 and Th 1–x U x O 2 systems, supporting their development as potential materials for nuclear fuels and irradiation-tolerant thin film targets in nuclear physics measurements.

Th1−xUxO2↗
DOE OSTI2022

Developing a Th Resonance Ionization Scheme: for Future Use in Age Dating SNM by Resonance Ionization Mass Spectrometry

We report the development of a Th resonance ionization scheme (RIS) for analyzing Th isotopes by resonance ionization mass spectrometry (RIMS) to enable age-dating via the 230 Th/ 234 U inter-elemental pair. This report summarizes the work that completes the first of two tasks that are required for developing U-Th dating via RIMS at the Laser Ionization of Neutrals (LION) laboratory at Lawrence Livermore National Laboratory (LLNL). The first task involves choosing and vetting an appropriate Th RIS for the LION instrument and simultaneous U and Th analysis.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
NASA NTRS1993

K, U, and Th behavior in Martian environmental conditions

The possibility of K, U, and Th content determination from orbit and in situ allows consideration of those elements as geochemical indicators in the planetary studies. In the case of Mars the unambiguous interpretations of such data in terms of igneous rocks are remarkably constrained by the widespread rock alteration and the existence of exogenic deposits. Besides, the terrestrial experience indicates that K, U, and Th contents could be used as indicators of environmental geochemical processes. Thus the determination of K, U, and Th contents in the Martian surface materials could provide the indirect data on the conditions of some exogenic geological processes. The speculations on the K, U, and Th behavior in the Martian environments show that aeolian and aqueous processes leads to the preferential accumulation of K, U, and Th in fine dust material. The separation of K, U, and Th on Mars is smaller in scale to that on Earth.

Zolotov, M. YU.↗
NASA NTRS2016

Metal-Silicate-Sulfide Partitioning of U, Th, and K: Implications for the Budget of Volatile Elements in Mercury

During formation of the solar system, the Sun produced strong solar winds, which stripped away a portion of the volatile elements from the forming planets. Hence, it was expected that planets closest to the sun, such as Mercury, are more depleted in volatile elements in comparison to other terrestrial planets. However, the MESSENGER mission detected higher than expected K/U and K/Th ratios on Mercury's surface, indicating a volatile content between that of Mars and Earth. Our experiments aim to resolve this discrepancy by experimentally determining the partition coefficients (D(sup met/sil)) of K, U, and Th between metal and silicate at varying pressure (1 to 5 GPa), temperature (1500 to 1900 C), oxygen fugacity (IW-2.5 to IW-6.5) and sulfur-content in the metal (0 to 33 wt%). Our data show that U, Th, and K become more siderophile with decreasing fO2 and increasing sulfur-content, with a stronger effect for U and Th in comparison to K. Using these results, the concentrations of U, Th, and K in the bulk planet were calculated for different scenarios, where the planet equilibrated at a fO2 between IW-4 and IW-7, assuming the existence of a FeS layer, between the core and mantle, with variable thickness. These models show that significant amounts of U and Th are partitioned into Mercury's core. The elevated superficial K/U and K/Th values are therefore only a consequence of the sequestration of U and Th into the core, not evidence of the overall volatile content of Mercury.

Habermann, M.↗
DOE OSTI2020

Materials Data on Th(CrGe)2 by Materials Project

ThCr2Ge2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Th is bonded in a 8-coordinate geometry to eight equivalent Cr and eight equivalent Ge atoms. All Th–Cr bond lengths are 3.38 Å. All Th–Ge bond lengths are 3.23 Å. Cr is bonded to four equivalent Th and four equivalent Ge atoms to form a mixture of edge, face, and corner-sharing CrTh4Ge4 tetrahedra. All Cr–Ge bond lengths are 2.48 Å. Ge is bonded in a 9-coordinate geometry to four equivalent Th, four equivalent Cr, and one Ge atom. The Ge–Ge bond length is 2.63 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Th(CoGe)2 by Materials Project

ThCo2Ge2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Th is bonded in a 8-coordinate geometry to eight equivalent Co and eight equivalent Ge atoms. All Th–Co bond lengths are 3.21 Å. All Th–Ge bond lengths are 3.22 Å. Co is bonded in a 4-coordinate geometry to four equivalent Th and four equivalent Ge atoms. All Co–Ge bond lengths are 2.37 Å. Ge is bonded in a 9-coordinate geometry to four equivalent Th, four equivalent Co, and one Ge atom. The Ge–Ge bond length is 2.63 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Th(GePd)2 by Materials Project

ThPd2Ge2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Th is bonded in a 8-coordinate geometry to eight equivalent Pd and eight equivalent Ge atoms. All Th–Pd bond lengths are 3.36 Å. All Th–Ge bond lengths are 3.30 Å. Pd is bonded in a 4-coordinate geometry to four equivalent Th and four equivalent Ge atoms. All Pd–Ge bond lengths are 2.54 Å. Ge is bonded in a 9-coordinate geometry to four equivalent Th, four equivalent Pd, and one Ge atom. The Ge–Ge bond length is 2.48 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Th(GeO)2 by Materials Project

Th(GeO)2 crystallizes in the tetragonal I4_1/amd space group. The structure is zero-dimensional and consists of eight Th(GeO)2 clusters. Th is bonded in a linear geometry to two equivalent O atoms. Both Th–O bond lengths are 2.14 Å. Ge is bonded in a distorted single-bond geometry to one O atom. The Ge–O bond length is 1.82 Å. O is bonded in a bent 150 degrees geometry to one Th and one Ge atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Th by Materials Project

Th is Tungsten structured and crystallizes in the cubic Im-3m space group. The structure is three-dimensional. Th is bonded in a distorted body-centered cubic geometry to eight equivalent Th atoms. All Th–Th bond lengths are 3.47 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Th by Materials Project

Th is Copper structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Th is bonded to twelve equivalent Th atoms to form a mixture of edge, face, and corner-sharing ThTh12 cuboctahedra. All Th–Th bond lengths are 3.56 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2025

ThO 2 and Th 1– x U x O 2 Nanoscale Materials and Thin Films for Nuclear Science Applications

This study investigates the dynamics and mechanisms of solution combustion synthesis (SCS) for the preparation of nanoscale ThO 2 and Th 1–x U x O 2 materials, utilizing metal nitrates (Th(NO 3 ) 4 and UO 2 (NO 3 ) 2 ) and acetylacetone (C 5 H 8 O 2 ) as reactants dissolved in a 2-methoxyethanol (C 3 H 8 O 2 ) solvent. By combining thermodynamic calculations, dynamic time–temperature profile measurements with differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), this research reveals how variations in acetylacetone concentration and uranium content influence the structural parameters of the synthesized oxides. The time–temperature measurements show that the heating rate and maximum combustion temperatures are sensitive to acetylacetone concentration. DSC-TGA results indicate shifts in exothermic peak temperatures as the uranium content changes. The complexation between thorium and acetylacetone emerges as a critical factor, impacting combustion parameters and the structural characteristics of the final products. The uniform distribution of Th and U in the Th 1–x U x O 2 solid solution and the formation of nanoscale particles with strained crystallites are considered essential for the low-temperature densification of these materials for nuclear fuel pellet applications. Additionally, high-quality ThO 2 and Th 1–x U x O 2 thin (100–150 nm) films are successfully synthesized via electrospray deposition of combustible solutions followed by a brief period of heat treatment. Furthermore, these films exhibit excellent structural and morphological uniformity, making them ideal candidates for nuclear measurements, irradiation damage studies, and investigations into the physical properties of both pure and mixed oxides.

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

Friends or Foes: Fundamental Principles of Th-Organic Scaffold Chemistry Using Zr-Analogs as a Guide

The fundamental interest in actinide chemistry, particularly for the development of thorium-based materials, is experiencing a renaissance owing to the recent and rapidly growing attention to fuel cycle reactors, radiological daughters for nuclear medicine, and efficient nuclear stockpile development. Herein, we uncover fundamental principles of thorium chemistry on the example of Th-based extended structures such as metal–organic frameworks in comparison with the discrete systems and zirconium extended analogs, demonstrating remarkable over two-and-half-year chemical stability of Th-based frameworks as a function of metal node connectivity, amount of defects, and conformational linker rigidity through comprehensive spectroscopic and crystallographic analysis as well as theoretical modeling. Despite exceptional chemical stability, we report the first example of studies focusing on the reactivity of the most chemically stable Th-based frameworks in comparison with the discrete Th-based systems such as metal–organic complexes and a cage, contrasting multicycle recyclability and selectivity (>97%) of the extended structures in comparison with the molecular compounds. Altogether, the presented work not only establishes the conceptual foundation for evaluating the capabilities of Th-based materials but also represents a milestone for their multifaceted future and foreshadows their potential to shape the next era of actinide chemistry.

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

Quantitative encapsulation and retention of 227 Th and decay daughters in core–shell lanthanum phosphate nanoparticles

Targeted alpha therapy (TAT) offers great promise for treating recalcitrant tumors and micrometastatic cancers. One drawback of TAT is the potential damage to normal tissues and organs due to the relocation of decay daughters from the treatment site. As such, the present study evaluates La( 227 Th)PO 4 core (C) and core +2 shells (C2S) nanoparticles (NPs) as a delivery platform of 227 Th to minimize systemic distribution of decay daughters, 223 Ra and 211 Pb. In vitro retention of decay daughters within La( 227 Th)PO 4 C NPs was influenced by the concentration of reagents used during synthesis, in which the leakage of 223 Ra was between 0.4 ± 0.2% and 20.3 ± 1.1% in deionized water. Deposition of two nonradioactive LaPO 4 shells onto La( 227 Th)PO 4 C NPs increased the retention of decay daughters to >99.75%. The toxicity of the nonradioactive LaPO 4 C and C2S NP delivery platforms was examined in a mammalian breast cancer cell line, BT-474. No significant decrease in cell viability was observed for a monolayer of BT-474 cells for NP concentrations below 233.9 μg mL –1 , however cell viability decreased below 60% when BT-474 spheroids were incubated with either LaPO 4 C or C2S NPs at concentrations exceeding 29.2 μg mL –1 . La( 227 Th)PO 4 C2S NPs exhibit a high encapsulation and in vitro retention of radionuclides with limited contribution to cellular cytotoxicity for TAT applications.

07 ISOTOPE AND RADIATION SOURCES↗
NASA NTRS1992

Experimental determination of U and Th partitioning between clinopyroxene and natural and synthetic basaltic liquid

Experimental measurements of U and the partition coefficients between clinopyroxene and synthetic and natural basaltic liquid are presented. The results demonstrate that crystal-liquid U-Th fractionation is fO2-dependent and that U in terrestrial magmas is not entirely tetravalent. During partial melting, the liquid will have a Th/U ratio less than the clinopyroxene in the source. The observed U-238 - Th-230 disequilibrium in MORB requires that the partial melt should have a U/Th ratio greater than the bulk source and therefore cannot result from clinopyroxene-liquid partitioning. Further, the magnitudes of the measured partition coefficients are too small to generate significant U-Th fractionation in either direction. Assuming that clinopyroxene contains the bulk of the U and Th in the MORB source, the results indicate that U-238 - Th-230 disequilibrium in MORB may not be caused by partial melting at all.

Latourrette, T. Z.↗
DOE OSTI2020

Materials Data on Th(MnGe)2 by Materials Project

Th(MnGe)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Th is bonded in a 8-coordinate geometry to eight equivalent Ge atoms. All Th–Ge bond lengths are 3.15 Å. Mn is bonded to four equivalent Ge atoms to form a mixture of edge and corner-sharing MnGe4 tetrahedra. All Mn–Ge bond lengths are 2.45 Å. Ge is bonded in a 9-coordinate geometry to four equivalent Th, four equivalent Mn, and one Ge atom. The Ge–Ge bond length is 2.67 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Th(TiH3)2 by Materials Project

ThTi2H6 crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Th is bonded in a 6-coordinate geometry to nine H atoms. There are a spread of Th–H bond distances ranging from 2.31–2.48 Å. There are two inequivalent Ti sites. In the first Ti site, Ti is bonded in a distorted hexagonal planar geometry to six H atoms. There is two shorter (1.83 Å) and four longer (1.91 Å) Ti–H bond length. In the second Ti site, Ti is bonded in a 6-coordinate geometry to six equivalent H atoms. All Ti–H bond lengths are 1.79 Å. There are two inequivalent H sites. In the first H site, H is bonded in a trigonal planar geometry to one Th and two Ti atoms. In the second H site, H is bonded to two equivalent Th and two equivalent Ti atoms to form a mixture of distorted corner and edge-sharing HTh2Ti2 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Th(TeI)2 by Materials Project

Th(TeI)2 crystallizes in the monoclinic C2/m space group. The structure is two-dimensional and consists of one Th(TeI)2 sheet oriented in the (0, 0, 1) direction. Th4+ is bonded in a 8-coordinate geometry to four Te1- and four equivalent I1- atoms. There are two shorter (3.21 Å) and two longer (3.24 Å) Th–Te bond lengths. There are two shorter (3.19 Å) and two longer (3.23 Å) Th–I bond lengths. There are two inequivalent Te1- sites. In the first Te1- site, Te1- is bonded in a 2-coordinate geometry to two equivalent Th4+ atoms. In the second Te1- site, Te1- is bonded in a 2-coordinate geometry to two equivalent Th4+ atoms. I1- is bonded in a distorted water-like geometry to two equivalent Th4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Th(NiH)2 by Materials Project

Th(NiH)2 crystallizes in the hexagonal P6/mmm space group. The structure is three-dimensional. Th is bonded in a hexagonal planar geometry to six equivalent H atoms. All Th–H bond lengths are 2.50 Å. Ni is bonded in a linear geometry to two equivalent H atoms. Both Ni–H bond lengths are 1.77 Å. H is bonded to three equivalent Th and two equivalent Ni atoms to form a mixture of edge and corner-sharing HTh3Ni2 trigonal bipyramids.

36 MATERIALS SCIENCE↗