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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 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Phase equilibria in iron-rich Sm–Fe–Ti and Sm–(Fe,Co)–Ti alloys at 1100–1200 °C

Iron-rich corners of ternary Sm–Fe–Ti phase diagram at 1100 °C and quasi-ternary Sm–Fe 0.8 Co 0.2 –Ti phase diagrams at 1100 and 1200 °C are constructed based on experimental investigation of equilibrated alloys with electron probe microanalysis, X-ray diffraction and thermomagnetic analysis. In addition, the upper boundaries of the temperature ranges of Sm(Fe,[Co,]Ti) 12 and Sm 3 (Fe,[Co,]Ti) 29 phases are determined with differential thermal analysis to update earlier rough estimates. The existence of a high-temperature phase of the Th 2 Ni 17 type, originally reported by Ivanova et al. [J. Alloys Compd. 224 (1995) 29], is confirmed. In the Sm–Fe 0.8 Co 0.2 –Ti system, the composition and equilibria of this hexagonal phase are established for 1200 °C; it is Sm-depleted (≈9.8 at.% Sm) compared to the 2:17 stoichiometry and it coexists with the rhombohedral 2:17 phase. The magnetic anisotropy of the cobalt-substituted Th 2 Ni 17 -type phase is planar, with the easy magnetization direction parallel to [100]. Equilibrium between a Sm-rich liquid phase and the 1:12 phase, which is important for the development of new high-performance permanent magnets, is absent up to 1000 °C, but does exist at 1100 °C (for the 1:12 phase with at least 8.7–8.9 at.% Ti) and at 1200 °C (for the 1:12 phase with as little as 7.4 at.% Ti). The development of magnets may be complicated, however, by an observed tendency of the high-temperature liquid to solidify into ferromagnetic phases including the Th 2 Ni 17 -type phase. The Curie temperatures of the α-(Fe,Ti), Sm(Fe,Ti) 12 , Sm 3 (Fe,Ti) 29 and rhombohedral Sm 2 (Fe,Ti) 17 phases are not only increased by the partial Co substitution for Fe, but their dependence on the Ti concentration is changed by this Co substitution from positive (or, for the 1:12 phase, zero) to negative values.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Absolute Decay Counting of $$^{146}$$Sm and $$^{147}$$Sm for Early Solar System Chronology

Sm-Nd chronometers use 146 Sm and 147 Sm to determine the ages of major events in the early Solar System. Their half-lives are the most important nuclear parameters deter mining the accuracy of chronometry. However, the 146 Sm half-life is not well-established: the published values differ by ~30%, which results in significant uncertainties in the So lar System timeline. We are re-measuring the half-lives of 146 Sm and 147 Sm using decay energy spectroscopy and metallic magnetic calorimeters to improve the accuracy of the Sm Nd chronometers. We report recent experimental results from our first measurement of a 147 Sm source, as well as status and plans for experiments on 146 Sm.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2021

Unveiling the mechanism of phase and morphology selections during the devitrification of Al-Sm amorphous ribbon

The complex interplay between energetic and kinetic factors that governs the phase and morphology selections can originate at the earliest stage of crystallization in the amorphous parent phases. Because of the extreme difficulties in capturing the microscopic nucleation process, a detailed picture of how initial disordered structures affect the transformation pathway remains unclear. Here, we report the experimental observation of widely varying phase selection and grain size evolution during the devitrification of a homogeneous melt-spun glassy ribbon. Two different crystalline phases, θ-Al 5 Sm and ε-Al 60 Sm 11 , are found to form in the different regions of the same metallic glass ribbon during the devitrification. The grain size of ε-Al 60 Sm 11 phase shows a strong spatial heterogeneity. Coarse-grained ε-Al 60 Sm 11 phase coupled with the small volume fraction of θ-Al 5 Sm phase is preferably formed close to wheel side of the melt-spun ribbon. Combining experimental characterization and computational simulations, we show that phase selection and microstructure evolution can be traced back to different types and populations of atomic clusters that serve as precursors for the nucleation of different crystalline phases. Inhomogeneous cooling rates cause different structure orders across the glass sample during the quenching process. Our findings provide direct insight into the effect of structural order on the crystallization pathways during the devitrification of metallic glass. It also opens an avenue to study the detailed nucleation process at the atomic level using the metallic glass as a platform and suggests the opportunity of microstructure and property design via controlling the cooling process.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2020

IUPAC-IUGS recommendation on the half-lives of 147 Sm and 146 Sm

In this paper, the IUPAC-IUGS joint Task Group “Isotopes in Geosciences” recommends a value of (106.25 ± 0.38) Ga for the half-life of 147 Sm, and a corresponding decay constant λ 147 = (6.524 ± 0.024) × 10 –12 a –1 , both with a coverage factor k = 2. For the extinct radionuclide 146 Sm two very different half-lives are used in the scientific community ( c . 68 and 103 Ma), to such a degree that no consensus value can be endorsed at present by the Task Group. Pending dedicated re-investigations it is recommended that papers using the 146 Sm decay to quantify the cosmo/geological evolution of (extra)terrestrial samples perform a twin set of calculations using both proposed half-lives.

146Sm↗
DOE OSTI2022

Enhanced CO 2 Methanation Activity of Sm 0.25 Ce 0.75 O 2-δ –Ni by Modulating the Chelating Agents-to-Metal Cation Ratio and Tuning Metal–Support Interactions

Highly active and selective CO 2 methanation catalysts are critical to CO 2 upgrading, synthetic natural gas production, and CO 2 emission reduction. Wet impregnation is widely used to synthesize oxide-supported metallic nanoparticles as the catalyst for CO 2 methanation. However, as the reagents cannot be homogeneously mixed at an atomic level, it is challenging to modulate the microstructure, crystal structure, chemical composition, and electronic structure of catalysts via wet impregnation. In this work, a scalable and straightforward catalyst fabrication approach has been designed and validated to produce Sm 0.25 Ce 0.75 O 2-δ -supported Ni (SDC–Ni) as the CO 2 methanation catalyst. By varying the chelating agents-to-total metal cations ratio (C/I ratio) during the catalyst synthesis, we can readily and simultaneously modulate the microstructure, metallic surface area, crystal structure, chemical composition, and electronic structure of SDC–Ni, consequently fine-tuning the oxide–support interactions and CO 2 methanation activity. The optimal C/I ratio (0.1) leads to an SDC–Ni catalyst that facilitates C–O bond cleavage and significantly improves CO 2 conversion at 250 °C. A CO 2 -to-CH 4 yield of >73% has been achieved at 250 °C. Furthermore, a stable operation of >1500 hours has been demonstrated, and no degradation is observed. Extensive characterizations were performed to fundamentally understand how to tune and enhance CO 2 methanation activity of SDC–Ni by modulating the C/I ratio. The correlation of physical, chemical, and catalytic properties of SDC–Ni with the C/I ratio is established and thoroughly elaborated in this work. This study could be applied to tune the oxide–support interactions of various catalysts for enhancing the catalytic activity.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Re-investigation of high-temperature phase equilibria in Fe-rich Sm–Fe–Ti alloys

Recently renewed attempts to develop high-performance rare-earth-lean permanent magnets based on the Sm(Fe,Ti) 12 compound have drawn attention to the limited knowledge about the high-temperature phase equilibria in the Sm–Fe–Ti system. Experimental investigation of equilibrated alloys with electron probe microanalysis, X-ray diffraction and thermomagnetic analysis revealed several inaccuracies in the currently accepted phase relations at 1000°C and allowed for a revision of the Fe-rich corner of the Sm–Fe–Ti phase diagram. The Sm(Fe,Ti) 12 and Sm 3 (Fe,Ti) 29 phases were found to have more extended Ti ranges of 5.1–9.7 at% and 2.8–6.9 at%, respectively. With increasing of the Ti content, the Curie temperature of the Sm(Fe,Ti) 12 remains nearly constant at 306–312°C, whereas that of the Sm 3 (Fe,Ti) 29 increases from 188°C to 207°C. The low-titanium Sm 3 (Fe,Ti) 29 phase equilibrates not only with the Sm(Fe,Ti) 12 and Sm2(Fe,Ti) 17 phases, but also with (α-Fe) solid solution. Newly demonstrated equilibrium between Sm 2 (Fe,Ti) 17 and TiFe 2 phases makes impossible the earlier reported equilibrium between the Sm 3 (Fe,Ti) 29 and Sm(Fe,Ti) 11 phases. Because of an invariant reaction at 1000 °C, the revised phase diagram also features a class II four-phase equilibrium Sm 3 (Fe,Ti) 29 + TiFe 2 + Sm(Fe,Ti) 12 + Sm 2 (Fe,Ti) 17 . Peritectic decomposition of the Sm(Fe,Ti) 11 phase, which occurs either at 1075°C or at 1087°C, was found to have among its products the Sm(Fe,Ti) 12 phase. Although no such equilibration was attempted, it must be possible to obtain above 1087°C a two-phase state composed of the Sm(Fe,Ti) 12 phase and a liquid – which is important for manufacturing of the Sm(Fe,Ti) 12 - based permanent magnets via the liquid-phase sintering.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sm(Ga2Cu)4 by Materials Project

Sm(CuGa2)4 crystallizes in the hexagonal P6/mmm space group. The structure is three-dimensional. there are two inequivalent Sm sites. In the first Sm site, Sm is bonded in a 8-coordinate geometry to twelve equivalent Cu and eight Ga atoms. All Sm–Cu bond lengths are 3.39 Å. All Sm–Ga bond lengths are 3.12 Å. In the second Sm site, Sm is bonded in a 8-coordinate geometry to six equivalent Cu and fourteen Ga atoms. All Sm–Cu bond lengths are 3.49 Å. There are eight shorter (3.18 Å) and six longer (3.30 Å) Sm–Ga bond lengths. Cu is bonded to two Sm, two equivalent Cu, and eight Ga atoms to form distorted CuSm2Ga8Cu2 cuboctahedra that share corners with five equivalent GaSm2Ga6Cu4 cuboctahedra, corners with nine equivalent CuSm2Ga8Cu2 cuboctahedra, edges with three equivalent CuSm2Ga8Cu2 cuboctahedra, edges with three equivalent GaSm2Ga6Cu4 cuboctahedra, faces with two equivalent GaSm2Ga6Cu4 cuboctahedra, and faces with eight equivalent CuSm2Ga8Cu2 cuboctahedra. Both Cu–Cu bond lengths are 2.61 Å. There are a spread of Cu–Ga bond distances ranging from 2.62–2.78 Å. There are five inequivalent Ga sites. In the first Ga site, Ga is bonded to two equivalent Sm, four equivalent Cu, and six Ga atoms to form distorted GaSm2Ga6Cu4 cuboctahedra that share corners with four equivalent GaSm2Ga6Cu4 cuboctahedra, corners with ten equivalent CuSm2Ga8Cu2 cuboctahedra, an edgeedge with one GaSm2Ga6Cu4 cuboctahedra, edges with six equivalent CuSm2Ga8Cu2 cuboctahedra, faces with four equivalent CuSm2Ga8Cu2 cuboctahedra, and faces with five equivalent GaSm2Ga6Cu4 cuboctahedra. There are a spread of Ga–Ga bond distances ranging from 2.73–2.85 Å. In the second Ga site, Ga is bonded in a 8-coordinate geometry to one Sm, three equivalent Cu, and four Ga atoms. The Ga–Ga bond length is 2.62 Å. In the third Ga site, Ga is bonded in a 8-coordinate geometry to one Sm, six equivalent Cu, and seven Ga atoms. There are one shorter (2.73 Å) and six longer (3.01 Å) Ga–Ga bond lengths. In the fourth Ga site, Ga is bonded in a 5-coordinate geometry to one Sm, four equivalent Cu, and three Ga atoms. The Ga–Ga bond length is 2.77 Å. In the fifth Ga site, Ga is bonded in a 12-coordinate geometry to two equivalent Sm, four equivalent Cu, and six Ga atoms. Both Ga–Ga bond lengths are 2.68 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sm(MnSn)6 by Materials Project

SmMn6Sn6 crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. there are two inequivalent Sm sites. In the first Sm site, Sm is bonded to eight Sn atoms to form distorted edge-sharing SmSn8 hexagonal bipyramids. There are a spread of Sm–Sn bond distances ranging from 3.02–3.20 Å. In the second Sm site, Sm is bonded to eight Sn atoms to form distorted edge-sharing SmSn8 hexagonal bipyramids. There are a spread of Sm–Sn bond distances ranging from 3.02–3.18 Å. There are four inequivalent Mn sites. In the first Mn site, Mn is bonded in a 12-coordinate geometry to six Sn atoms. There are four shorter (2.76 Å) and two longer (2.85 Å) Mn–Sn bond lengths. In the second Mn site, Mn is bonded in a 12-coordinate geometry to six Sn atoms. There are a spread of Mn–Sn bond distances ranging from 2.75–2.85 Å. In the third Mn site, Mn is bonded in a 12-coordinate geometry to six Sn atoms. There are a spread of Mn–Sn bond distances ranging from 2.72–2.85 Å. In the fourth Mn site, Mn is bonded in a 12-coordinate geometry to six Sn atoms. There are a spread of Mn–Sn bond distances ranging from 2.75–2.84 Å. There are nine inequivalent Sn sites. In the first Sn site, Sn is bonded in a 8-coordinate geometry to one Sm, six Mn, and one Sn atom. The Sn–Sm bond length is 3.02 Å. There are four shorter (2.84 Å) and two longer (2.85 Å) Sn–Mn bond lengths. The Sn–Sn bond length is 3.01 Å. In the second Sn site, Sn is bonded in a 12-coordinate geometry to three Sm and six Mn atoms. In the third Sn site, Sn is bonded in a 6-coordinate geometry to six Mn atoms. In the fourth Sn site, Sn is bonded in a 12-coordinate geometry to three Sm and six Mn atoms. In the fifth Sn site, Sn is bonded in a 6-coordinate geometry to six Mn atoms. In the sixth Sn site, Sn is bonded in a 8-coordinate geometry to two equivalent Sm and six Mn atoms. In the seventh Sn site, Sn is bonded in a 7-coordinate geometry to one Sm and six Mn atoms. In the eighth Sn site, Sn is bonded in a 8-coordinate geometry to one Sm, six Mn, and one Sn atom. The Sn–Sn bond length is 3.01 Å. In the ninth Sn site, Sn is bonded in a 8-coordinate geometry to one Sm, six Mn, and one Sn atom. The Sn–Sn bond length is 3.01 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Understanding neutron capture processes in uranium deposits using combined U-Sm-Nd isotopic compositions

Valuable insights into the history and evolution of a geologic deposit can be found by investigating neutron capture reactions. Thermal neutron capture reactions occur within both the samarium (Sm) and the uranium (U) systems, where 149 Sm and 235 U can capture neutrons to become 150 Sm and 236 U, respectively. Although largely unexplored, paired measurements of 150 Sm and 236 U could be important for understanding neutron capture effects within uranium ore bodies, and such measurements are potentially useful in nuclear forensics for assessing a material's provenance or mineral exploration. In this work, we refined measurement procedures of Sm isotope compositions utilizing MC-ICPMS. While geologic reference materials were found to have indistinguishable Sm isotope compositions, we found significant isotope variations consistent with nuclear field shift among synthetic Sm standards. Here, this observation highlights that future high-precision Sm isotope investigations need to carefully evaluate synthetic standard(s) against geologic reference materials until an unfractionated and agreed-upon standard is identified. Here, we applied this method to a set of nine uranium ores from the South Australian Beverley North uranium deposits. Although 236 U excesses had been previously reported for these U ores, we found no measurable isotopic shifts in 149 Sm- 150 Sm at the current level of precision (±5 parts per million). One possible explanation for this disparity in the observed neutron capture signatures between U and Sm is that the source(s) of the U and Sm in these ores may be decoupled. This is consistent with the finding that these ores have variable 143 Nd/ 144 Nd, thus demonstrating that diverse sources were involved in the formation of the Beverley North deposits. Alternatively, this deposit may be too young (<50Ma) to have accumulated measurable neutron capture effects in Sm to be detected with the methods employed here.

Mineral exploration↗
DOE OSTI2020

Materials Data on Sm(ReO5)3 by Materials Project

Sm(ReO5)3 crystallizes in the orthorhombic Pna2_1 space group. The structure is three-dimensional. Sm is bonded in a 9-coordinate geometry to nine O atoms. There are a spread of Sm–O bond distances ranging from 2.38–2.54 Å. There are three inequivalent Re sites. In the first Re site, Re is bonded in a tetrahedral geometry to four O atoms. There are a spread of Re–O bond distances ranging from 1.73–1.79 Å. In the second Re site, Re is bonded in a tetrahedral geometry to four O atoms. There is two shorter (1.73 Å) and two longer (1.78 Å) Re–O bond length. In the third Re site, Re is bonded in a tetrahedral geometry to four O atoms. There is two shorter (1.73 Å) and two longer (1.78 Å) Re–O bond length. There are fifteen inequivalent O sites. In the first O site, O is bonded in a bent 150 degrees geometry to one Sm and one Re atom. In the second O site, O is bonded in a distorted linear geometry to one Sm and one Re atom. In the third O site, O is bonded in a single-bond geometry to one Sm atom. In the fourth O site, O is bonded in a single-bond geometry to one Re atom. In the fifth O site, O is bonded in a bent 150 degrees geometry to one Sm and one Re atom. In the sixth O site, O is bonded in a distorted bent 150 degrees geometry to one Sm and one Re atom. In the seventh O site, O is bonded in a single-bond geometry to one Re atom. In the eighth O site, O is bonded in a single-bond geometry to one Re atom. In the ninth O site, O is bonded in a single-bond geometry to one Re atom. In the tenth O site, O is bonded in a single-bond geometry to one Re atom. In the eleventh O site, O is bonded in a single-bond geometry to one Re atom. In the twelfth O site, O is bonded in a bent 150 degrees geometry to one Sm and one Re atom. In the thirteenth O site, O is bonded in a single-bond geometry to one Sm atom. In the fourteenth O site, O is bonded in a single-bond geometry to one Sm atom. In the fifteenth O site, O is bonded in a bent 150 degrees geometry to one Sm and one Re atom.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Effect of vanadium on phase composition and hard magnetic properties of as-solidified and heat-treated Sm–Fe–(Ti,V) alloys

Although the intrinsic magnetic properties of Ti-stabilized Sm(Fe,Co,Ti) 12 compounds exhibit potential of excellent rare-earth-lean permanent magnets, it has been much easier to realize large coercivities with the isostructural compounds stabilized by either V or by certain combinations of Ti and V. To elucidate the influence of V on the microstructure and magnetic properties, a series of Sm 8.1 Fe 78.4 (Ti 1-x V x ) 13.5 alloys was studied after arc-melting and annealing at 850–1000 °C. The alloys were found to fall into three groups. For x ≤ 0.2, solidification generates mostly the Sm(Fe,Ti,V) 12 phase, but annealing converts at least part of it into the non-magnetic Sm(Fe,Ti,V) 11 and the magnetically soft Sm 2 (Fe,Ti,V) 17 phases. For 0.2 < x < 0.6, the alloys solidify into a near-equilibrium mixture of the Sm(Fe,Ti,V) 12 , TiFe 2 and Sm-rich phases. For x ≥ 0.6, solidification generates large fractions of α-Fe solid solution and Sm-rich phases; an annealing step is necessary to complete the formation of Sm(Fe,Ti,V) 12 phase. Also, for x ≥ 0.6 the temperature below which the Sm(Fe,Ti,V) 12 phase is stable decreases with x, as does the fraction of this phase formed during solidification. Here, the differences between these three groups of alloys suggest different strategies for developing hard magnetic properties, with the likelihood of a success increasing with increasing x. For x ≥ 0.6, heat treatment alone is demonstrated to generate a microstructure of micron and submicron Sm(Fe,Ti 1-x V x ) 12 crystallites separated by a Sm-rich phase and exhibiting a coercivity with values up to 3.5 and 5.7 kOe for x = 0.8 and 1.0, respectively.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sm by Materials Project

Sm is alpha La structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. there are two inequivalent Sm sites. In the first Sm site, Sm is bonded to twelve Sm atoms to form a mixture of edge, face, and corner-sharing SmSm12 cuboctahedra. There are six shorter (3.61 Å) and six longer (3.65 Å) Sm–Sm bond lengths. In the second Sm site, Sm is bonded to twelve Sm atoms to form a mixture of edge, face, and corner-sharing SmSm12 cuboctahedra. All Sm–Sm bond lengths are 3.65 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sm by Materials Project

Sm is alpha Samarium structured and crystallizes in the trigonal R-3m space group. The structure is three-dimensional. there are two inequivalent Sm sites. In the first Sm site, Sm is bonded to twelve Sm atoms to form a mixture of edge, face, and corner-sharing SmSm12 cuboctahedra. There are six shorter (3.61 Å) and six longer (3.66 Å) Sm–Sm bond lengths. In the second Sm site, Sm is bonded to twelve Sm atoms to form a mixture of edge, face, and corner-sharing SmSm12 cuboctahedra. There are three shorter (3.62 Å) and six longer (3.66 Å) Sm–Sm bond lengths.

36 MATERIALS SCIENCE↗