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At least 253 records · Page 14
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Sm(NiP)2 by Materials Project

SmNi2P2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Sm2+ is bonded in a distorted body-centered cubic geometry to eight equivalent P3- atoms. All Sm–P bond lengths are 3.02 Å. Ni2+ is bonded to four equivalent P3- atoms to form a mixture of edge and corner-sharing NiP4 tetrahedra. All Ni–P bond lengths are 2.29 Å. P3- is bonded in a 9-coordinate geometry to four equivalent Sm2+, four equivalent Ni2+, and one P3- atom. The P–P bond length is 2.38 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sm(BC)2 by Materials Project

SmB2C2 crystallizes in the tetragonal P4/mbm space group. The structure is three-dimensional. Sm2+ is bonded in a body-centered cubic geometry to eight equivalent C4- atoms. All Sm–C bond lengths are 2.75 Å. B3+ is bonded in a distorted trigonal planar geometry to three equivalent C4- atoms. There is one shorter (1.53 Å) and two longer (1.61 Å) B–C bond length. C4- is bonded in a 3-coordinate geometry to four equivalent Sm2+ and three equivalent B3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sm(AlSi)2 by Materials Project

Al2Si2Sm crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. Sm2+ is bonded to six equivalent Si4- atoms to form SmSi6 octahedra that share corners with twelve equivalent AlSi4 tetrahedra, edges with six equivalent SmSi6 octahedra, and edges with six equivalent AlSi4 tetrahedra. All Sm–Si bond lengths are 3.02 Å. Al3+ is bonded to four equivalent Si4- atoms to form AlSi4 tetrahedra that share corners with six equivalent SmSi6 octahedra, corners with six equivalent AlSi4 tetrahedra, edges with three equivalent SmSi6 octahedra, and edges with three equivalent AlSi4 tetrahedra. The corner-sharing octahedra tilt angles range from 22–54°. There are three shorter (2.52 Å) and one longer (2.53 Å) Al–Si bond lengths. Si4- is bonded to three equivalent Sm2+ and four equivalent Al3+ atoms to form a mixture of distorted corner and edge-sharing SiSm3Al4 pentagonal bipyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sm(Mo3S4)2 by Materials Project

SmMo6S8 crystallizes in the trigonal R-3 space group. The structure is three-dimensional. Sm3+ is bonded in a body-centered cubic geometry to eight S2- atoms. There are two shorter (2.77 Å) and six longer (3.01 Å) Sm–S bond lengths. Mo+2.17+ is bonded to five S2- atoms to form a mixture of corner and edge-sharing MoS5 square pyramids. There are a spread of Mo–S bond distances ranging from 2.41–2.59 Å. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded in a 5-coordinate geometry to one Sm3+ and four equivalent Mo+2.17+ atoms. In the second S2- site, S2- is bonded in a 4-coordinate geometry to one Sm3+ and three equivalent Mo+2.17+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sm(GaS2)2 by Materials Project

SmGa2S4 crystallizes in the orthorhombic Cccm space group. The structure is three-dimensional. Sm2+ is bonded in a 8-coordinate geometry to eight S2- atoms. There are four shorter (2.92 Å) and four longer (2.98 Å) Sm–S bond lengths. Ga3+ is bonded to four S2- atoms to form edge-sharing GaS4 tetrahedra. There are a spread of Ga–S bond distances ranging from 2.34–2.45 Å. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded in a 4-coordinate geometry to two equivalent Sm2+ and two equivalent Ga3+ atoms. In the second S2- site, S2- is bonded to two equivalent Sm2+ and two equivalent Ga3+ atoms to form a mixture of distorted edge and corner-sharing SSm2Ga2 trigonal pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sm(SiIr)2 by Materials Project

SmIr2Si2 crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Sm2+ is bonded in a 8-coordinate geometry to eight Si4- atoms. There are four shorter (3.19 Å) and four longer (3.20 Å) Sm–Si bond lengths. There are two inequivalent Ir3+ sites. In the first Ir3+ site, Ir3+ is bonded to four equivalent Si4- atoms to form a mixture of edge and corner-sharing IrSi4 tetrahedra. All Ir–Si bond lengths are 2.45 Å. In the second Ir3+ site, Ir3+ is bonded in a 5-coordinate geometry to five Si4- atoms. There are one shorter (2.40 Å) and four longer (2.44 Å) Ir–Si bond lengths. There are two inequivalent Si4- sites. In the first Si4- site, Si4- is bonded in a 4-coordinate geometry to four equivalent Sm2+ and four equivalent Ir3+ atoms. In the second Si4- site, Si4- is bonded in a 9-coordinate geometry to four equivalent Sm2+ and five Ir3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sm(MgSb)2 by Materials Project

SmMg2Sb2 crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. Mg2+ is bonded to four equivalent Sb3- atoms to form MgSb4 tetrahedra that share corners with six equivalent SmSb6 octahedra, corners with six equivalent MgSb4 tetrahedra, edges with three equivalent SmSb6 octahedra, and edges with three equivalent MgSb4 tetrahedra. The corner-sharing octahedra tilt angles range from 16–57°. There are three shorter (2.84 Å) and one longer (2.91 Å) Mg–Sb bond lengths. Sm2+ is bonded to six equivalent Sb3- atoms to form SmSb6 octahedra that share corners with twelve equivalent MgSb4 tetrahedra, edges with six equivalent SmSb6 octahedra, and edges with six equivalent MgSb4 tetrahedra. All Sm–Sb bond lengths are 3.25 Å. Sb3- is bonded to four equivalent Mg2+ and three equivalent Sm2+ atoms to form a mixture of distorted corner and edge-sharing SbSm3Mg4 pentagonal bipyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sm(CoB)4 by Materials Project

SmCo4B4 crystallizes in the tetragonal P4_2/n space group. The structure is three-dimensional. Sm2+ is bonded in a 8-coordinate geometry to eight equivalent B+1.50- atoms. There are four shorter (2.79 Å) and four longer (2.82 Å) Sm–B bond lengths. Co1+ is bonded in a 5-coordinate geometry to five equivalent B+1.50- atoms. There are a spread of Co–B bond distances ranging from 1.99–2.44 Å. B+1.50- is bonded in a 5-coordinate geometry to two equivalent Sm2+, five equivalent Co1+, and one B+1.50- atom. The B–B bond length is 1.79 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sm(BRu)4 by Materials Project

SmRu4B4 crystallizes in the tetragonal I4_1/acd space group. The structure is three-dimensional. Sm3+ is bonded to twelve equivalent B3- atoms to form distorted SmB12 cuboctahedra that share corners with twelve equivalent RuB5 trigonal bipyramids, edges with twelve equivalent SmB12 cuboctahedra, edges with four equivalent RuB5 trigonal bipyramids, and faces with twelve equivalent RuB5 trigonal bipyramids. There are a spread of Sm–B bond distances ranging from 2.99–3.23 Å. Ru+2.25+ is bonded to five equivalent B3- atoms to form distorted RuB5 trigonal bipyramids that share corners with three equivalent SmB12 cuboctahedra, corners with eight equivalent RuB5 trigonal bipyramids, an edgeedge with one SmB12 cuboctahedra, edges with six equivalent RuB5 trigonal bipyramids, and faces with three equivalent SmB12 cuboctahedra. There are a spread of Ru–B bond distances ranging from 2.16–2.31 Å. B3- is bonded in a 6-coordinate geometry to three equivalent Sm3+, five equivalent Ru+2.25+, and one B3- atom. The B–B bond length is 1.80 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sm(SiIr)2 by Materials Project

SmIr2Si2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Sm2+ is bonded in a 8-coordinate geometry to eight equivalent Si4- atoms. All Sm–Si bond lengths are 3.26 Å. Ir3+ is bonded in a 4-coordinate geometry to four equivalent Si4- atoms. All Ir–Si bond lengths are 2.42 Å. Si4- is bonded in a 4-coordinate geometry to four equivalent Sm2+ and four equivalent Ir3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sm(Co2B)6 by Materials Project

SmCo12B6 crystallizes in the trigonal R-3m space group. The structure is three-dimensional. Sm3+ is bonded in a hexagonal planar geometry to six equivalent B3- atoms. All Sm–B bond lengths are 3.05 Å. There are two inequivalent Co+1.25+ sites. In the first Co+1.25+ site, Co+1.25+ is bonded in a T-shaped geometry to three equivalent B3- atoms. All Co–B bond lengths are 2.10 Å. In the second Co+1.25+ site, Co+1.25+ is bonded to four equivalent B3- atoms to form a mixture of distorted edge and corner-sharing CoB4 trigonal pyramids. There are two shorter (2.03 Å) and two longer (2.04 Å) Co–B bond lengths. B3- is bonded in a 7-coordinate geometry to one Sm3+ and seven Co+1.25+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sm(BC)2 by Materials Project

SmB2C2 crystallizes in the tetragonal P4_2/mmc space group. The structure is three-dimensional. Sm2+ is bonded in a 8-coordinate geometry to eight equivalent C4- atoms. All Sm–C bond lengths are 2.77 Å. B3+ is bonded in an L-shaped geometry to two equivalent C4- atoms. Both B–C bond lengths are 1.61 Å. C4- is bonded in a 2-coordinate geometry to four equivalent Sm2+, two equivalent B3+, and one C4- atom. The C–C bond length is 1.43 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2022

High and temperature-insensitive piezoelectric performance in the lead-free Sm-doped BiFeO 3 –BaTiO 3 ceramics with high Curie temperature

Large sensor piezoelectric constant (d 33 = 334 pC/N) and superior actuator piezoelectric constant (d 33 * = 552 pm/V) as well as a high Curie temperature (T C = 454 °C) were obtained simultaneously in the lead-free 0.67Bi 1.03 FeO 3 -0.33Ba 1-x Sm x TiO 3 ceramics. Such an excellent and temperature-insensitive piezoelectric performance with only 10% temperature variation of piezoelectric strain at the range of 25–125 °C is highly desirable for real applications. The structural origin of the enhanced piezoelectric performance is mainly attributed to the morphotropic phase boundary and the highest known tetragonality (c T /a T = 1.02) in such materials. Transmission electron microscopy and electro-mechanical phenomenological theory demonstrate that the superior d 33 and d 33 * are associated with the hybrids nanodomains (60–90 nm) and flattened thermodynamic energy profile owing to the local structure heterogeneity. Furthermore, these results are superior as the piezoelectric properties are temperature-independent and the material has large d 33 *, and high TC compared to other lead-free piezoelectric ceramics.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Novel structured Sm 0.5 Sr 0.5 CoO 3-δ cathode for intermediate and low temperature solid oxide fuel cells

The performance of solid oxide fuel cell (SOFC) can be significantly enhanced using nanostructured cathode obtained by infiltration/impregnation method. However, this method has been limited due to multi-step preparation process and instability of the obtained nanoscale catalyst under long-term operation. We report here a simple, cost-effective and reproducible approach to fabricate nanostructured Sm 0.5 Sr 0.5 CoO 3-δ (SSC) cathode with enhanced performance and stability. The SSC powders were prepared by a freeze-drying method through a combustion route using Pluronic F-127 as the template. The SSC freeze-drying powders have unique morphology and a significant phase change at 750 °C. The oxygen non-stoichiometry (δ) of the SSC powders is 0.18 at room temperature, while the δ values are 0.66, 0.75 and 0.90 at 600 °C, 700 °C and 800 °C, respectively. The novel structured SSC cathode was prepared by screen-printing and one-step sintering process using the freeze-drying SSC powders. Maximum cell power densities of 0.83 and 1.13 W cm -2 are achieved at 550 °C and 600 °C, respectively for single cells with the novel structured SSC cathode. Moreover, single cells show excellent stability at 600 °C under a current density of 600 mA cm -2 over 250 h. This work expands opportunities to exploit nanotechnology in a wide range of intermediate and low temperature energy conversion devices.

25 ENERGY STORAGE↗
DOE OSTI2026

Role of washing solvents in defining the magnetic performance of Sm 2 Fe 17 N 3 obtained by reduction diffusion

Calciothermic reduction-diffusion (RD) is one of the leading synthesis methods for Sm 2 Fe 17 N 3 (SmFeN), but sintering of such RD-derived powders is hampered by oxidation and CaO byproducts. Here, we systematically evaluate how post-synthesis washing solvents govern powder chemistry and magnetic performance. RD-synthesized SmFeN powder was washed with several aqueous and non-aqueous solvents using identical washing protocols. This was followed by an assessment of both the as-washed powder as well as after annealing at 425 °C. Phase content was quantified by synchrotron PXRD and Rietveld refinement and SEM/EDS. The oxygen content of the powders was determined via inert gas fusion and the magnetization by DC magnetometry. While all aqueous-based solutions were able to remove CaO, the non-aqueous solutions were only effective with extended washing times. Prior to annealing, the crystalline phases and magnetic properties of the as-washed powders were largely the same regardless of washing solvent. However, differences emerge after annealing, where water-based washing markedly lowers the coercivity (H c ~3.8-4.3 kOe). In contrast, non-aqueous NH 4 Cl-methanol washing protocols were more effective in preserving coercivity (H c ~4.9-5.9 kOe). We attribute this to lower oxygen content in the non-aqueous samples (~9,400 ppm v ~6,400 ppm, respectively) which in turn reduced the formation of α-Fe during annealing. These results highlight the importance of solvent choice in washing RD-synthesized SmFeN and demonstrate that non-aqueous protocols, which better limit oxidation, outperform aqueous solvents despite the need for longer washing times.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Physical origins of the varying performance and unusual transport behaviors among thermoelectric A Mg 2 Sb 2 materials ( A = Ca, Sr, Sm, Yb, and Mg)

Contrary to the similar thermoelectric performance among both AZn 2 Sb 2 and AMg 2 Bi 2 compounds, their isostructural counterparts, AMg 2 Sb 2 , can exhibit thermoelectric figure of merit values that vary by orders of magnitude with different A elements. Here, we reveal physical origins accounting for the significantly differing performance among AMg 2 Sb 2 -based compounds (A = Ca, Sr, Sm, Yb, and Mg) through comprehensive analyses, where it is shown that the dispar- ities in performance at the macroscale essentially originate from the widely varying activation energies that equal amounts of dopant can induce. Meanwhile, a few unusual transport behaviors regarding electrical conductivity, carrier concentration, or lattice thermal con- ductivity among these compounds have been identified, and we also present their rationales in depth. Furthermore, this mechanism-focused study can not only promote further understanding of the complex transport behaviors in condensed matter but be instrumental in rationally tun- ing the physical properties of materials as well.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Temperature and anion ligand field dependence of LnCl 3 (Ln = Nd, Dy, Sm) electronic absorption spectra in LiCl–KCl eutectic molten salt

A comprehensive knowledge of the coordination, bonding, and speciation of elements in molten salt mixtures is necessary to understand and predict the chemical and physical properties of the salt. Absorption spectroscopy can yield information about the chemistry of species of interest in alkali halide molten salt mixtures by revealing information about the electronic structure and transitions of those species. In this study, ultraviolet (UV), visible (vis), and near-infrared (NIR) absorption spectroscopy was used to examine changes to the electronic structure of trivalent Nd, Sm, and Dy in LiCl–KCl eutectic molten salt with changes in temperature and the anion composition of the melt. With increasing temperature, changes to spectral features suggest a distortion of the coordination complexes. Changes to lineshape with the substitution of alternative halide anions were examined and analyzed, revealing differences in the coordination for I – versus F – with the lanthanides. Gaussian peak fitting was used to show that the changes in lineshape with the progressive addition of F – anions can be explained by the superposition of a set of absorption bands from complexes with all Cl – anion ligands and a set of blueshifted absorption bands from complexes containing both F – and Cl – anion ligands. Finally, this work yields a new method to analyze and interpret change to electronic absorption spectra for f-block elements dissolved in alkali halide molten salts as well as new observations of the interactions of larger and smaller halide anions with lanthanides in Cl – -based molten salts.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2021

High-coercivity ThMn 12 -type monocrystalline Sm–Zr–Fe–Co–Ti particles by high-temperature reduction diffusion

The ThMn 12 -type (Sm,Zr)1(Fe,Co,Ti) 12 compounds have the potential of powerful permanent magnets. Magnetically hard and anisotropic powders of such compound have been prepared by subjecting elemental oxides and Co mixed with Ca and CaO dispersant to a succession of high-energy ball-milling, reduction diffusion at 990–1220 °C and repeated washing. The size of the resulting ThMn 12 -type crystallites, their coercivity and fraction of monocrystalline particles were all found to increase with the reduction-diffusion temperature. Particles synthesized at 1220 °C were highly monocrystalline with a mean size of 0.54 μm and, after a magnetic-field alignment, exhibited a coercivity of 1.26 T and a full-density-projected maximum energy product of at least 209 kJ/m 3 (26.3 MGOe). Here, the strong positive effect of the reduction-diffusion temperature on the coercivity has been attributed to separation of the crystallites and to decrease in the incidence of structural defects.

36 MATERIALS SCIENCE↗