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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↗
DOE OSTI2025

Coordination Chemistry and Photoluminescence of Sm(II) Dibenzo-24-crown-8 Complexes

Three Sm(II) dibenzo-24-crown-8 (db24c8) complexes were synthesized in anhydrous, air-free conditions via the reaction of SmI 2 with db24c8 and tetrabutylammonium tetraphenylborate ([TBA][BPh 4 ]; where needed) in acetonitrile (CH 3 CN), dimethoxyethane (DME), and tetrahydrofuran (THF) to yield [Sm(db24c8)(CH 3 CN) 2 ][BPh 4 ][I]·CH 3 CN, [Sm(db24c8)(DME)]I 2 , and [Sm(db24c8)(THF) 2 ]I 2 , respectively. In each case, a 10-coordinate, staggered dodecahedral (2:6:2) environment is formed around the Sm 2+ center that is completed by either two solvent molecules (CH 3 CN or THF) or one bidentate solvent molecule (DME). Inner-sphere solvent molecules can be excluded by reacting SmI 2 with db24c8 in 1:3 THF:toluene to yield Sm(db24c8)I 2 . Here, this molecule features a distorted, eight-coordinate, hexagonal pyramidal Sm 2+ metal center, where the coordinated db24c8 molecule shows a torsion angle unexpectedly close to the 180° antiperiplanar arrangement and two uncoordinated db24c8 oxygen atoms. Solution UV–vis–NIR measurements demonstrate that Sm 2+ is a good size match for the cavity of various db24c8 conformations and that Eu 2+ and Yb 2+ exhibit competition between acetonitrile solvation and the Eu 2+ and Yb 2+ /db24c8 complexes in solution. During excitation by 546 nm light, both [Sm(db24c8)(DME)]I 2 and [Sm(db24c8)(THF) 2 ]I 2 exhibit mixed 5d → 4f and 4f → 4f emission at 20 °C and exclusively 4f → 4f at −180 °C, whereas Sm(db24c8)I 2 only shows 5d → 4f emission regardless of temperature. Photoluminescence from [Sm(db24c8)(CH 3 CN) 2 ][BPh 4 ][I]·CH 3 CN is quenched.

Cations↗
DOE OSTI2020

Materials Data on Sm(Ga3Co)3 by Materials Project

Sm(CoGa3)3 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Sm is bonded in a 12-coordinate geometry to thirteen Ga atoms. There are a spread of Sm–Ga bond distances ranging from 3.07–3.57 Å. There are three inequivalent Co sites. In the first Co site, Co is bonded in a 8-coordinate geometry to one Co and seven Ga atoms. The Co–Co bond length is 2.74 Å. There are a spread of Co–Ga bond distances ranging from 2.33–2.63 Å. In the second Co site, Co is bonded in a 9-coordinate geometry to two equivalent Co and seven Ga atoms. Both Co–Co bond lengths are 2.68 Å. There are a spread of Co–Ga bond distances ranging from 2.32–2.57 Å. In the third Co site, Co is bonded in a 11-coordinate geometry to three Co and eight Ga atoms. There are a spread of Co–Ga bond distances ranging from 2.54–2.98 Å. There are ten inequivalent Ga sites. In the first Ga site, Ga is bonded in a 6-coordinate geometry to two equivalent Sm, three Co, and two Ga atoms. There are one shorter (2.49 Å) and one longer (2.60 Å) Ga–Ga bond lengths. In the second Ga site, Ga is bonded in a 6-coordinate geometry to two equivalent Sm, two equivalent Co, and two Ga atoms. The Ga–Ga bond length is 2.56 Å. In the third Ga site, Ga is bonded in a 1-coordinate geometry to three Co and seven Ga atoms. There are a spread of Ga–Ga bond distances ranging from 2.61–2.86 Å. In the fourth Ga site, Ga is bonded in a 10-coordinate geometry to one Sm, two Co, and seven Ga atoms. There are a spread of Ga–Ga bond distances ranging from 2.81–2.92 Å. In the fifth Ga site, Ga is bonded in a 10-coordinate geometry to two equivalent Sm, two equivalent Co, and six Ga atoms. There are one shorter (2.61 Å) and two longer (2.74 Å) Ga–Ga bond lengths. In the sixth Ga site, Ga is bonded in a 11-coordinate geometry to two equivalent Sm, three Co, and six Ga atoms. There are one shorter (2.65 Å) and two longer (2.79 Å) Ga–Ga bond lengths. In the seventh Ga site, Ga is bonded in a 4-coordinate geometry to two equivalent Sm, two equivalent Co, and four equivalent Ga atoms. In the eighth Ga site, Ga is bonded in a 8-coordinate geometry to two equivalent Sm, two equivalent Co, and four equivalent Ga atoms. In the ninth Ga site, Ga is bonded in a 10-coordinate geometry to two equivalent Sm and eight Ga atoms. In the tenth Ga site, Ga is bonded in a 3-coordinate geometry to five Co atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sm(Al5Ru)2 by Materials Project

Sm(RuAl5)2 crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. Sm is bonded in a 10-coordinate geometry to four equivalent Ru and sixteen Al atoms. All Sm–Ru bond lengths are 3.48 Å. There are a spread of Sm–Al bond distances ranging from 3.18–3.69 Å. Ru is bonded in a 10-coordinate geometry to two equivalent Sm and ten Al atoms. There are a spread of Ru–Al bond distances ranging from 2.58–2.77 Å. There are five inequivalent Al sites. In the first Al site, Al is bonded in a 2-coordinate geometry to one Sm and two equivalent Ru atoms. In the second Al site, Al is bonded in a distorted linear geometry to two equivalent Sm and two equivalent Ru atoms. In the third Al site, Al is bonded in a 2-coordinate geometry to two equivalent Sm and two equivalent Ru atoms. In the fourth Al site, Al is bonded in a distorted bent 120 degrees geometry to two equivalent Sm and two equivalent Ru atoms. In the fifth Al site, Al is bonded in a 12-coordinate geometry to one Sm and two equivalent Ru atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sm(SeO4)2 by Materials Project

Sm(SeO3)2O2 crystallizes in the orthorhombic P2_12_12_1 space group. The structure is three-dimensional and consists of four hydrogen peroxide molecules and one Sm(SeO3)2 framework. In the Sm(SeO3)2 framework, Sm is bonded to seven O atoms to form distorted SmO7 pentagonal bipyramids that share corners with two equivalent SeO4 tetrahedra and edges with two equivalent SmO7 pentagonal bipyramids. There are a spread of Sm–O bond distances ranging from 2.34–2.50 Å. There are two inequivalent Se sites. In the first Se site, Se is bonded in a trigonal non-coplanar geometry to three O atoms. There are a spread of Se–O bond distances ranging from 1.70–1.76 Å. In the second Se site, Se is bonded to four O atoms to form distorted SeO4 tetrahedra that share corners with two equivalent SmO7 pentagonal bipyramids and corners with two equivalent SeO4 tetrahedra. There are a spread of Se–O bond distances ranging from 1.69–2.44 Å. There are six inequivalent O sites. In the first O site, O is bonded in a distorted bent 120 degrees geometry to one Sm and one Se atom. In the second O site, O is bonded in a 3-coordinate geometry to two equivalent Sm and one Se atom. In the third O site, O is bonded in a bent 120 degrees geometry to one Sm and one Se atom. In the fourth O site, O is bonded in a distorted bent 120 degrees geometry to two equivalent Se atoms. In the fifth O site, O is bonded in a distorted trigonal non-coplanar geometry to two equivalent Sm and one Se atom. In the sixth O site, O is bonded in a bent 150 degrees geometry to one Sm and one Se atom.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Chemical bonding, phase stability and magnetic property in Sm 2 Fe 17 X 3 (X=H, C, N): A first-principles perspective

As a promising alternative to Nd–Fe–B magnets, the critical rare earth free Sm 2 Fe 17 X 3 (X = C, N) exhibits potential for high-performance magnets. However, their poor phase stability remains a major obstacle to developing bulk magnets. We investigated the phase stability and intrinsic magnetic properties of Sm 2 Fe 17 X 3 (X = H, C, N) using first-principles calculations and chemical bond analysis. The formation energies are negative, while the decomposition energies are −1.53, 0.348, and −0.74 eV per formula unit for X = H, C, and N, respectively, which is responsible for the weak thermal stability. Our chemical bond analysis reveals that the bonding asymmetry between Sm–X and Fe–X interactions creates local structural distortions and degrades the phase stability of Sm 2 Fe 17 X 3 . The project Crystal Orbital Hamilton Population (-pCOHP) analysis indicates that the Sm–X bonding remains positive up to the Fermi level, indicating stable bonding interactions. Here, in contrast, the Fe–X bonding becomes negative near the Fermi level, signifying anti-bonding contributions that reduce structural stability. Interstitial atoms X expand the lattice and enhance Fe magnetic moments, but Fe–X bonding suppresses neighboring Fe moments. Electron transfer from Sm to X modifies the valence state of Sm and the crystal field at the site, contributing to enhanced magnetocrystalline anisotropy in Sm 2 Fe 17 X 3 . Among the interstitial elements, carbon and nitrogen—with their larger atomic radius and higher electronegativity—induce greater lattice expansion and form stronger bonds with neighboring Sm and Fe atoms compared to hydrogen. Consequently, Sm 2 Fe 17 X 3 (X = C and N) exhibits better phase stability and significant improvement in magnetic properties.

Chemical bonding↗
DOE OSTI2025

Enhanced Phase Stability of Sm 2 (Fe, Al) 17 C x

Aluminum doping can improve the phase stability of metastable compound Sm 2 Fe 17 C x with a high carbon content (x > 1.5). We investigated the preferential site substitution of Al, chemical bonding, and structural stability in Sm 2 (Fe,Al) 17 C 3 using first-principle calculations. Our results reveal a strong correlation between the preferential substitution of Fe by Al and the atomic site chemical environment, which affects the overall phase stability. Specifically, Al preferentially occupies the 9d site in Sm 2 (Fe,Al) 17 C 3 . At the same time, Al prefers the site 6c in its parent phase Sm 2 (Fe,Al) 17 . Partial replacement of Fe with Al leads to a more negative formation energy, indicating enhanced thermodynamic stability. Crystal Orbital Hamilton Population (COHP) and Crystal Orbital Bond Index (COBI) analysis suggest that insertion of carbon weakens the bonding strength of Sm-Fe (18f) and Sm-Fe (18h), resulting in metastability of Sm 2 Fe 17 C x . Doping Al strengthens Al-Fe, Al-Sm, Sm-Fe (18f, 18h) and Fe–C bonding in Sm 2 (Fe,Al) 17 C 3 , as revealed by calculated COHP and COBI. These effects contribute to improved phase stability in the Al-doped 2:17 interstitial compound.

chemical bonding↗
DOE OSTI2020

Materials Data on Sm(Al3Fe)3 by Materials Project

Sm(FeAl3)3 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Sm is bonded in a 12-coordinate geometry to six Fe and fourteen Al atoms. There are two shorter (3.38 Å) and four longer (3.40 Å) Sm–Fe bond lengths. There are a spread of Sm–Al bond distances ranging from 3.08–3.36 Å. There are two inequivalent Fe sites. In the first Fe site, Fe is bonded in a 12-coordinate geometry to two equivalent Sm and ten Al atoms. There are a spread of Fe–Al bond distances ranging from 2.53–2.75 Å. In the second Fe site, Fe is bonded in a 12-coordinate geometry to two equivalent Sm, two equivalent Fe, and eight Al atoms. Both Fe–Fe bond lengths are 2.53 Å. There are a spread of Fe–Al bond distances ranging from 2.50–2.66 Å. There are three inequivalent Al sites. In the first Al site, Al is bonded in a 12-coordinate geometry to two equivalent Sm, three Fe, and seven Al atoms. There are a spread of Al–Al bond distances ranging from 2.65–2.91 Å. In the second Al site, Al is bonded in a 10-coordinate geometry to one Sm, three Fe, and six Al atoms. There are one shorter (2.74 Å) and one longer (2.78 Å) Al–Al bond lengths. In the third Al site, Al is bonded in a distorted linear geometry to two equivalent Sm, two equivalent Fe, and eight Al atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sm(InCu)6 by Materials Project

Sm(CuIn)6 crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. Sm is bonded in a 8-coordinate geometry to twelve Cu and eight In atoms. There are four shorter (3.47 Å) and eight longer (3.58 Å) Sm–Cu bond lengths. There are a spread of Sm–In bond distances ranging from 3.14–3.23 Å. There are two inequivalent Cu sites. In the first Cu site, Cu is bonded to two equivalent Sm, four Cu, and six In atoms to form a mixture of distorted corner, edge, and face-sharing CuSm2In6Cu4 cuboctahedra. There are two shorter (2.67 Å) and two longer (2.72 Å) Cu–Cu bond lengths. There are a spread of Cu–In bond distances ranging from 2.77–2.83 Å. In the second Cu site, Cu is bonded to two equivalent Sm, four equivalent Cu, and six In atoms to form a mixture of distorted corner, edge, and face-sharing CuSm2In6Cu4 cuboctahedra. There are a spread of Cu–In bond distances ranging from 2.79–2.88 Å. There are three inequivalent In sites. In the first In site, In is bonded in a 8-coordinate geometry to one Sm, six Cu, and one In atom. The In–In bond length is 3.06 Å. In the second In site, In is bonded in a 10-coordinate geometry to one Sm and six Cu atoms. In the third In site, In is bonded in a 8-coordinate geometry to two equivalent Sm and six Cu atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2026

First-principles insights into Si substitution effects in Sm 2 (Fe,Si) 17 C x magnet

The partial substitution of Fe by Si enhances the phase stability of Sm 2 Fe 17 C x magnets with x > 1.0. Here, we elucidate the Si-substitution scheme and its impact on phase stability and magnetic properties in Sm 2 (Fe,Si) 17 C 3 from first-principles calculations and chemical bonding analysis. The calculated substitution energies for Si at various Fe sites are negative, indicating improved phase stability. Si preferentially substitutes Fe atoms at the 9d site in Sm 2 (Fe,Si) 17 C 3 while it tends to enter the Fe 18h site in Sm 2 (Fe,Si) 17 . This difference in site preference is attributed to the distinct chemical environments surrounding the Fe (Si) sites in the two compounds. Si substitution favors the formation of Sm–Si bonds while minimizing the Si–C and Si–Si interactions. Crystal orbital Hamilton populations and crystal orbital bond index calculations indicate that the partial replacement of Fe with Si strengthens the chemical bonding of Sm–Fe 3 (18f) and Sm–Fe 4 (18h) and improves overall phase stability in Sm 2 (Fe,Si) 17 C 3 . Beyond the dilution effect, Si substitution also reduces the magnetic moments of neighboring Fe atoms, a phenomenon linked to the strong Fe–Si bonding. These findings highlight the dual role of Si in modifying both the structural and magnetic characteristics of Sm 2 Fe 17 -based magnetic compounds.

Chemical bonding↗
DOE OSTI2020

Materials Data on Sm(NiGe)3 by Materials Project

Sm(NiGe)3 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Sm is bonded in a 4-coordinate geometry to eight Ni and eight Ge atoms. There are four shorter (3.20 Å) and four longer (3.24 Å) Sm–Ni bond lengths. There are four shorter (3.12 Å) and four longer (3.20 Å) Sm–Ge bond lengths. There are two inequivalent Ni sites. In the first Ni site, Ni is bonded in a 9-coordinate geometry to four equivalent Sm and five Ge atoms. There are one shorter (2.33 Å) and four longer (2.39 Å) Ni–Ge bond lengths. In the second Ni site, Ni is bonded in a 8-coordinate geometry to two equivalent Sm and six Ge atoms. There are four shorter (2.49 Å) and two longer (2.51 Å) Ni–Ge bond lengths. There are four inequivalent Ge sites. In the first Ge site, Ge is bonded in a body-centered cubic geometry to eight equivalent Ni atoms. In the second Ge site, Ge is bonded in a body-centered cubic geometry to eight equivalent Ni atoms. In the third Ge site, Ge is bonded in a 9-coordinate geometry to four equivalent Sm and five Ni atoms. In the fourth Ge site, Ge is bonded in a 4-coordinate geometry to four equivalent Sm and four equivalent Ni atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sm(NiBi)2 by Materials Project

Sm(NiBi)2 crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Sm is bonded in a 12-coordinate geometry to eight Ni and nine Bi atoms. There are four shorter (3.29 Å) and four longer (3.60 Å) Sm–Ni bond lengths. There are a spread of Sm–Bi bond distances ranging from 3.45–3.61 Å. There are two inequivalent Ni sites. In the first Ni site, Ni is bonded in a 9-coordinate geometry to four equivalent Sm and five Bi atoms. There are one shorter (2.53 Å) and four longer (2.65 Å) Ni–Bi bond lengths. In the second Ni site, Ni is bonded in a distorted body-centered cubic geometry to four equivalent Sm and four equivalent Bi atoms. All Ni–Bi bond lengths are 2.65 Å. There are two inequivalent Bi sites. In the first Bi site, Bi is bonded in a 5-coordinate geometry to five equivalent Sm and five Ni atoms. In the second Bi site, Bi is bonded in a 4-coordinate geometry to four equivalent Sm and four equivalent Ni atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sm(GeIr)2 by Materials Project

Sm(IrGe)2 crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Sm is bonded in a 12-coordinate geometry to eight Ir and eight Ge atoms. There are four shorter (3.23 Å) and four longer (3.37 Å) Sm–Ir bond lengths. All Sm–Ge bond lengths are 3.27 Å. There are two inequivalent Ir sites. In the first Ir site, Ir is bonded in a 4-coordinate geometry to four equivalent Sm and four equivalent Ge atoms. All Ir–Ge bond lengths are 2.51 Å. In the second Ir site, Ir is bonded in a 9-coordinate geometry to four equivalent Sm and five Ge atoms. There are one shorter (2.44 Å) and four longer (2.50 Å) Ir–Ge bond lengths. There are two inequivalent Ge sites. In the first Ge site, Ge is bonded in a 4-coordinate geometry to four equivalent Sm and four equivalent Ir atoms. In the second Ge site, Ge is bonded in a 9-coordinate geometry to four equivalent Sm and five Ir atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sm(CuSn)2 by Materials Project

Sm(CuSn)2 crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Sm is bonded in a 12-coordinate geometry to eight Cu and eight Sn atoms. There are four shorter (3.36 Å) and four longer (3.43 Å) Sm–Cu bond lengths. There are four shorter (3.36 Å) and four longer (3.55 Å) Sm–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 Sm and four equivalent Sn atoms. All Cu–Sn bond lengths are 2.60 Å. In the second Cu site, Cu is bonded in a 9-coordinate geometry to four equivalent Sm and five Sn atoms. There are one shorter (2.51 Å) and four longer (2.64 Å) Cu–Sn bond lengths. There are two inequivalent Sn sites. In the first Sn site, Sn is bonded in a 4-coordinate geometry to four equivalent Sm and four equivalent Cu atoms. In the second Sn site, Sn is bonded in a 9-coordinate geometry to four equivalent Sm and five Cu atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sm(GePt)2 by Materials Project

Sm(PtGe)2 crystallizes in the monoclinic P2_1 space group. The structure is three-dimensional. Sm is bonded in a 7-coordinate geometry to eight Pt and eight Ge atoms. There are a spread of Sm–Pt bond distances ranging from 3.26–3.44 Å. There are a spread of Sm–Ge bond distances ranging from 3.23–3.40 Å. There are two inequivalent Pt sites. In the first Pt site, Pt is bonded in a 9-coordinate geometry to four equivalent Sm and five Ge atoms. There are a spread of Pt–Ge bond distances ranging from 2.45–2.52 Å. In the second Pt site, Pt is bonded in a 4-coordinate geometry to four equivalent Sm and four equivalent Ge atoms. There are a spread of Pt–Ge bond distances ranging from 2.53–2.57 Å. There are two inequivalent Ge sites. In the first Ge site, Ge is bonded in a 9-coordinate geometry to four equivalent Sm and five Pt atoms. In the second Ge site, Ge is bonded in a 4-coordinate geometry to four equivalent Sm and four equivalent Pt atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sm(GePt)2 by Materials Project

Sm(PtGe)2 crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Sm is bonded in a 12-coordinate geometry to eight Pt and eight Ge atoms. There are four shorter (3.32 Å) and four longer (3.35 Å) Sm–Pt bond lengths. There are four shorter (3.30 Å) and four longer (3.32 Å) Sm–Ge bond lengths. There are two inequivalent Pt sites. In the first Pt site, Pt is bonded in a 4-coordinate geometry to four equivalent Sm and four equivalent Ge atoms. All Pt–Ge bond lengths are 2.56 Å. In the second Pt site, Pt is bonded in a 9-coordinate geometry to four equivalent Sm and five Ge atoms. There are one shorter (2.45 Å) and four longer (2.52 Å) Pt–Ge bond lengths. There are two inequivalent Ge sites. In the first Ge site, Ge is bonded in a 4-coordinate geometry to four equivalent Sm and four equivalent Pt atoms. In the second Ge site, Ge is bonded in a 9-coordinate geometry to four equivalent Sm and five Pt atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sm(Fe5Si)2 by Materials Project

Sm(Fe5Si)2 crystallizes in the orthorhombic Fmmm space group. The structure is three-dimensional. Sm is bonded in a 12-coordinate geometry to sixteen Fe and four equivalent Si atoms. There are a spread of Sm–Fe bond distances ranging from 2.99–3.19 Å. All Sm–Si bond lengths are 3.15 Å. There are three inequivalent Fe sites. In the first Fe site, Fe is bonded in a 10-coordinate geometry to one Sm, eleven Fe, and two equivalent Si atoms. There are a spread of Fe–Fe bond distances ranging from 2.33–2.94 Å. Both Fe–Si bond lengths are 2.55 Å. In the second Fe site, Fe is bonded to two equivalent Sm and ten Fe atoms to form FeSm2Fe10 cuboctahedra that share corners with four equivalent SiSm2Fe8Si2 cuboctahedra, corners with fourteen FeSm2Fe10 cuboctahedra, edges with four equivalent FeSm2Fe8Si2 cuboctahedra, edges with four equivalent SiSm2Fe8Si2 cuboctahedra, faces with four equivalent SiSm2Fe8Si2 cuboctahedra, and faces with ten FeSm2Fe10 cuboctahedra. There are two shorter (2.40 Å) and four longer (2.41 Å) Fe–Fe bond lengths. In the third Fe site, Fe is bonded to two equivalent Sm, eight Fe, and two equivalent Si atoms to form distorted FeSm2Fe8Si2 cuboctahedra that share corners with four equivalent SiSm2Fe8Si2 cuboctahedra, corners with fourteen FeSm2Fe10 cuboctahedra, edges with two equivalent SiSm2Fe8Si2 cuboctahedra, edges with five FeSm2Fe10 cuboctahedra, faces with four equivalent SiSm2Fe8Si2 cuboctahedra, and faces with eleven FeSm2Fe10 cuboctahedra. There are one shorter (2.65 Å) and one longer (2.66 Å) Fe–Fe bond lengths. Both Fe–Si bond lengths are 2.40 Å. Si is bonded to two equivalent Sm, eight Fe, and two equivalent Si atoms to form distorted SiSm2Fe8Si2 cuboctahedra that share corners with six equivalent SiSm2Fe8Si2 cuboctahedra, corners with twelve FeSm2Fe10 cuboctahedra, edges with eight FeSm2Fe10 cuboctahedra, faces with two equivalent SiSm2Fe8Si2 cuboctahedra, and faces with twelve FeSm2Fe10 cuboctahedra. Both Si–Si bond lengths are 2.40 Å.

36 MATERIALS SCIENCE↗