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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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11 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Syntheses and Characterization of Tetrazolate-Based Lanthanide Compounds and Selective Crystallization Separation of Neodymium and Dysprosium

Selective crystallization offers new opportunities for separating neodymium and dysprosium, which are considerably important in permanent magnets. Two water-soluble nitrogen-rich tetrazolate-based ligands, dtp 2– (H 2 dtp = 2,3-di-1H-tetrazol-5-ylpyrazine) and H 2 ibt – [H 3 ibt = 4,5-bis(tetrazol-5-yl)imidazole], allow the separation of Nd 3+ and Dy 3+ through selective crystallization. The reactions of Ln 3+ with the ligand Na 2 (dtp)·2H 2 O lead to two distinct phases, Na[Ln(dtp)(H 2 O) 8 ](dtp)·H 2 O (Lndtp1; Ln = La–Pr) and [Ln(H 2 O) 8 ](Hdtp)(dtp)·H 2 O (Lndtp2; Ln = Nd and Sm–Lu). Three different compound types, [Ln(H 2 ibt) 2 (H 2 O) 6 ](H 2 ibt)·3(H 2 O) (Lnibt1; Ln = La or Ce), [Ln(H 2 ibt)(H 2 O) 7 ](H 2 ibt) 2 ·4(H 2 O) (Lnibt2; Ln = Pr or Nd), and [Ln(Hibt)(H 2 ibt)(H 2 O) 4 ]·4+x(H 2 O) (Lnibt3; Ln = Sm–Lu), are obtained from reacting Ln 3+ and Na(H 2 ibt)·3(H 2 O). Two different phases are observed for Nd(Lnibt2) and Dy(Lnibt3) in the system of H 2 ibt – , which leads to crystallization-based separation of Nd/Dy with a separation factor of 32 ± 0.7, 10 times higher than that of dtp 2– , and a short separation time of 20 s (1 day for dtp 2– ). As a result, the higher performance of H 2 ibt – compared to that of dtp2– provides guidance for the rational design of water-soluble tetrazolate-derived ligands for selective crystallization.

Crystal structure↗
DOE OSTI2025

Similar but Different: Structural and Spectroscopic Characterization of Series of Neodymium, Europium, Americium, and Curium Coordination Complexes

Series of curium, americium, europium, and neodymium complexes with five different polyoxometalate (POM) ligands were structurally and spectroscopically characterized: Na x Cs y H z [M(XW 11 O 39 ) 2 ]· n H 2 O, where M = Nd 3+ , Eu 3+ , Am 3+ , or Cm 3+ and X = B 3+ , Ga 3+ , Si 4+ , Ge 4+ , or P 5+ . This first “serial approach” on transplutonium chemistry was allowed by minimizing the amount of f-element needed per synthesis down to ∼10 μg. This offers a unique opportunity to contrast structural and spectroscopic properties of trivalent actinide with those of lanthanide compounds under identical conditions. The results showcase that although actinide(III) and lanthanide(III) can make isostructural complexes, their solid-state coordination chemistries deviate significantly. The curium and americium compounds were found to be more uniform than their europium and neodymium counterparts, respectively. The particular symmetry of the Cm-POMs also enables the observation of rarely seen emission bands, which hints at vibronic coupling or new emissive pathways. Additionally, the Cm-POM and Eu-POM complexes were characterized via steady-state and time-resolved excitation and emission spectroscopy in solutions containing five different counterions (Li + , Na + , K + , Rb + , or Cs + ), representing 50 combinations of alkali/[M III (XW 11 ) 2 ] n − complexes. The Cm-POMs respond to the alkali counterions by improving symmetry from Li + to Cs + , while the Eu-POMs do the opposite. The luminescence lifetimes of the Cm-POMs also depart from the ideal Kimura equation. Finally, this study provides a rare, and perhaps the most comprehensive, experimental data set comparing heavy actinides and lanthanides via single crystal XRD plus, solution-state, solid-state, and time-resolved emission spectroscopy and demonstrates that lanthanides are only a coarse approximation for actinide elements.

chemical structure↗
DOE OSTI2026

Synthesis of Lanthanide-Based Intermetallic Silicides

Lanthanide-containing materials are of interest because of their useful magnetic and electronic behavior. To study this intrinsic behavior, researchers need high-quality single crystals to avoid interference from grain boundaries or defects commonly found in polycrystalline samples. One method for growing single crystals is metal-flux synthesis, an approach that promotes crystal growth at lower reaction temperatures thus providing access to complex intermetallic phases. My project focuses on synthesizing novel lanthanide-containing intermetallic silicides related to previously reported f-element compounds with the Gd1??Fe4Si10?? structure type. I investigated reactions targeting lanthanum, praseodymium, neodymium, samarium, europium, and gadolinium-containing products, and used scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS) to identify promising lanthanide-containing phases. I prepared reactions by loading lanthanide oxides, Co, Si, Al, and Ga into alumina crucibles in a 0.2:1:1:10:10 Ln2O3/Co/Si/Al/Ga mmol ratio, where Ln = La, Nd, Pr, Sm, Eu, or Gd. The reactions were sealed in quartz tubes, heated in a furnace, and centrifuged to separate crystals from excess flux. Afterwards, I mechanically isolated single crystals and prepared them for characterization. Pr-, Nd-, and Sm-containing reactions were confirmed through SEM-EDS to have formed the targeted quaternary phase. Single crystal X-ray diffraction (SC-XRD) data showed the Nd-containing crystals exhibited a hexagonal unit cell associated with the Gd1??Fe4Si10?? structure type. La- and Eu-containing reactions instead formed competing Co(Al/Ga/Si)3 phase crystals. Single-crystal XRD, powder XRD, and magnetic susceptibility and heat-capacity measurements will be collected for the remaining lanthanide-containing crystals. This data will help determine the complete crystal structure of the lanthanide analogues, their phase purity and whether they exhibit localized magnetic behavior, magnetic ordering, or other electronic signatures that can be compared with the previously reported actinide analogues. The disordered structure of this intermetallic family is associated with unusual magnetic and electronic behavior meaning lanthanide analogues may show potential as thermoelectric materials. Developing new thermoelectric candidate materials is relevant to energy efficiency and waste-heat recovery, which supports DOE’s broader goal of advancing science and technology solutions for America’s energy needs.

37 - INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL C↗
DOE OSTI2022

A physics-based model of cladding wastage layer formation rate

In this report, lower length scale simulations to inform an engineering-scale model of fuel-cladding chemical interaction (FCCI) conducted under the auspices of the Nuclear Energy Advanced Modeling and Simulation (NEAMS) program in FY22 are described. An overall strategy for the implementation of the BISON model is described, and the past and current lower length scale work on FCCI formation is put into the context of this overall strategy. Density functional theory and kinetic Monte Carlo simulations are used to determine the diffusion coefficient of neodymium in iron. Density functional theory calculations are also used to parameterize a parabolic approximation for the dependence of free energy on composition for the intermetallic compound Fe 17 Nd 2 . A phase-field model of the Fe-Nd system was developed that includes the random solid solution body-centered cubic phase and the intermetallic Fe 17 Nd 2 . The model was used to simulate growth of the intermetallic layer in a diffusion couple and the results were compared to experiment. The model’s prediction of the parabolic growth constant is within 40 % of the experimental value. The model is also used to simulate the formation of a grain boundary attack layer that is observed in experiment. The simulations show enhanced Nd concentration along the grain boundaries, but do not clearly show formation of a Fe 17 Nd 2 layer

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2021

Bulk and surface diffusion of neodymium in alpha-uranium: Ab initio calculations and kinetic Monte Carlo simulations

A fundamental understanding of lanthanide transport in metallic fuels is critical for high fidelity modeling of the fuel-cladding chemical interaction (FCCI) phenomenon, which can lead to the formation of brittle intermetallic compounds and premature failure of the cladding. Here we report a combined ab initio density functional theory (DFT) and kinetic Monte Carlo (KMC) study of the bulk diffusivity of Nd in α-U, fully taking into account the effect of radiation enhanced diffusion. In this work, the vacancy mechanism is considered to be the dominant mechanism for the bulk diffusion of Nd since a Nd interstitial is found to be intrinsically unstable in α-U. The surface diffusivity of a Nd adatom on α-U (001) surface has been further predicted using KMC simulations parameterized by DFT calculations. The present study suggests that Nd transport via the surface diffusion mechanism can be many orders of magnitude faster than bulk diffusion. Furthermore, the results from the present lower length scale study can be used to inform mesoscale phase-field simulations to determine the effective diffusion coefficient of Nd through α-U with a porous microstructure.

36 MATERIALS SCIENCE↗
DOE OSTI2024

High-pressure high-temperature synthesis of NdRe 2

In this study, we report the synthesis of a new cubic neodymium-rhenium metallic alloy NdRe 2 through the utilization of high pressure and laser heating in a diamond anvil cell. NdRe 2 crystallizes in the Fd$\overline{3}$m space group with a lattice parameter equal to 7.486 (2) Å and Z = 8 at 24 (1) GPa and 2,200 (100) K. It was studied using high-pressure single-crystal X-ray diffraction. The compound crystallizes in the cubic MgCu 2 structure type. Its successful synthesis further proves that high-pressure high-temperature conditions can be used to obtain alloys holding a Laves phase structure. Ab initio calculations were done to predict the mechanical properties of the material. We also discuss the usage of extreme conditions to synthesize and study materials present in the nuclear waste.

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

Nd, SbNd and Sb 3 Nd 4 and their interactions with the cladding alloy HT9

Lanthanide fission products, such as neodymium, formed during the irradiation of metallic fuels are known to cause deleterious effects from chemical interactions occurring at the fuel-cladding interface; a phenomenon known as fuel-cladding chemical interaction (FCCI). The use of fuel-based additives that bind with the lanthanide elements within the fuel meat, alleviating their interactions at the fuel-cladding interface, is one potential method proposed to mitigate the FCCI phenomenon and extend the burnup potential of such metallic fuel systems. In this study, antimony (Sb) is evaluated as one such additive, and neodymium (Nd) is used to represent the lanthanides. A Sb-Nd alloy is fabricated, which consists of two intermetallic phases, SbNd and Sb 3 Nd 4 . Isothermal diffusion couple experiments are carried out at 675 °C for 24 h between Nd and the Fe-12Cr based HT9 cladding alloy. The results are compared against similar diffusion couple experiments carried out between the Sb-Nd alloy and also HT9. Inter-diffusion between Nd/HT9 diffusion couple is characterized and the phases Fe 17 Nd 5 and Fe 17 Nd 2 were found to form whereas no interactions were observed in the Sb-Nd/HT9 diffusion couple. The lack of compound forming tendencies between Fe, the primary alloying constituent of HT9, and SbNd is elucidated through density functional theory (DFT) calculations on enthalpy of mixing, aligning well with the experimental observations. Lastly, the strong binding of Nd with Sb appears to be favorable, alleviating Nd interactions with HT9 constituent elements.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2022

Single crystal synthesis and magnetic properties of a Shastry-Sutherland lattice compound BaNd 2 ZnS 5

In this study, single crystals of a Shastry-Sutherland magnetic semiconductor, BaNd 2 ZnS 5 , were synthesized through a high-temperature solution growth technique. Physical properties were characterized by powder and single crystal x-ray diffraction, temperature- and field-dependent magnetization, and temperature-dependent specific heat measurements. BaNd 2 ZnS 5 orders antiferromagnetically at 2.9 K, with magnetic moments primarily aligned within the $ab$ -plane. Magnetic isothermal measurements show metamagnetic transitions at ~ 15 kOe for the [110] direction and ~ 21 kOe for the [100] direction. Estimated magnetic entropy suggests a double ground state for each neodymium ion.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Direct Extraction of Uranium-Lanthanide Oxides in Tributyl Phosphate

Abstract Direct extraction of used nuclear fuel (UNF) in an organic solution could be more efficient than the previous practice with aqueous solutions. However, the UNF would need to be treated via voloxidiation before being processed using solvent extraction. The voloxidation process can form oxide and/or nitrate compounds. This work investigated the dissolution of uranium/lanthanide oxides in 30 vol % TBP diluted in dodecane (pre-equilibrated with 4 M nitric acid) in a glass reactor with air sparging to ascertain the uranium/lanthanide oxide dissolution behavior prior to scaling the process. The uranium/lanthanide oxides were prepared by co-precipitating uranium/lanthanide nitrates with hydroxide and then calcined to form a mixed oxide. While the relative concentrations of the lanthanides are not representative of used nuclear fuel, the neodymium and erbium allowed ease of tracking dissolution with visible spectroscopy. Cerium was used as a surrogate for plutonium. The dissolution rate of the oxides was similar but incomplete. A miniscule amount of cerium, as cerium oxide, took several months to slowly dissolve; however, when co-precipitated with uranium and other lanthanides, a significant amount of cerium dissolved readily.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2020

Pronounced Pressure Dependence of Electronic Transitions for Americium Compared to Isomorphous Neodymium and Samarium Mellitates

The mellitate ion is relevant in spent nuclear fuel processing and is utilized as a surrogate for studying the interactions of f elements with humic acids. A wealth of different coordination modes gives the potential for diverse structural chemistry across the actinide series. In this study, an americium mellitate, 243 Am 2 [(C 6 (COO – ) 6 ](H 2 O) 8 ·2H 2 O (1-Am), has been synthesized and characterized using structural analysis and spectroscopy at ambient and elevated pressures. 1-Am was then compared to isomorphous neodymium (1-Nd) and samarium (1-Sm) mellitates via bond-length analysis and pressure dependence of their Laporte-forbidden f → f transitions. Results show that the pressure dependence of the f → f transitions of 1-Am is significantly greater than that observed in 1-Nd and 1-Sm, with average shifts of 21.4, 4.7, and 3.6 cm –1 /GPa, respectively. Finally, this greater shift found in 1-Am shows further evidence that the 5f orbitals are more affected than the 4f orbitals when pressure is applied to isostructural compounds.

Actinides↗
DOE OSTI2025

Material extrusion with integrated compression molding of NdFeB/SmFeN nylon bonded magnets using small- and large-scale pellet-based 3D-printers

High-density bonded rare-earth magnets are manufactured using pellet-fed additive manufacturing (AM)/material extrusion and an integrated additive manufacturing-compression molding (AM-CM) process. Neodymium iron boron – samarium iron nitride in polyamide 12 (NdFeB-SmFeN/PA12) of 93 % weight fraction (65 % volume fraction) are used for the study. The mechanical properties (tensile strength and modulus), magnetic properties (maximum energy density, coercivity, remanence) are reported. Manufacturing parameters such as layer height, barrel temperatures, screw speed and gantry feed rate are optimized to obtain the highest possible density of the magnets using a small-scale desktop material extrusion printer. Large scale integrated additive manufacturing-compression molding (AM-CM) is then utilized to increase the density of the magnets by reducing porosity defects common in the material extrusion process. The density of as-printed magnets was 5.2 g/cm 3 with a BH max value of 124.14 kJ/m 3 , tensile strength of 20 MPa and a modulus of 2 GPa. AM-CM increased the density of the compound by 5.5 % (5.49 g/cm 3 ). The reduction in porosity was confirmed using X-ray tomography (XCT). Improvement in mechanical strength of the material was also observed, with an increase in tensile strength of 25 % (25.09 MPa) and increase in tensile modulus of 275 % (5.49 GPa). Scanning electron microscopy showed increased particle-matrix adhesion with the integrated AM-CM process.

36 MATERIALS SCIENCE↗