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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Sm2Fe17 by Materials Project

Sm2Fe17 crystallizes in the trigonal R-3m space group. The structure is three-dimensional. Sm is bonded in a 10-coordinate geometry to nineteen Fe atoms. There are a spread of Sm–Fe bond distances ranging from 3.04–3.28 Å. There are four inequivalent Fe sites. In the first Fe site, Fe is bonded to two equivalent Sm and ten Fe atoms to form FeSm2Fe10 cuboctahedra that share corners with fourteen FeSm2Fe10 cuboctahedra, edges with six equivalent FeSm3Fe9 cuboctahedra, and faces with ten FeSm2Fe10 cuboctahedra. There are a spread of Fe–Fe bond distances ranging from 2.44–2.61 Å. In the second Fe site, Fe is bonded in a 12-coordinate geometry to two equivalent Sm and ten Fe atoms. There are a spread of Fe–Fe bond distances ranging from 2.48–2.76 Å. In the third Fe site, Fe is bonded to three equivalent Sm and nine Fe atoms to form a mixture of corner, edge, and face-sharing FeSm3Fe9 cuboctahedra. There are two shorter (2.49 Å) and one longer (2.65 Å) Fe–Fe bond lengths. In the fourth Fe site, Fe is bonded in a 2-coordinate geometry to one Sm and thirteen Fe atoms. The Fe–Fe bond length is 2.40 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Chemical bond and phase stability of Ga-doped Sm2Fe17Cx magnet

Sm2Fe17C3 phase (2:17) is metastable and exhibits excellent intrinsic hard magnetic properties. Doping elements such as Ga facilitate the formation of a single-phase 2:17 structure in arc-melted Sm2Fe17Cx alloys, which opens a promising route for fabricating fully dense bulk Sm2Fe17Cx magnets via high-temperature techniques such as melting and sintering. First-principles electronic structure calculation indicates that Ga prefers to partially replace Fe at the 9d and 18h crystallographic sites in Sm2Fe17C3 and Sm2Fe17, respectively. This difference in site preference is attributed to the distinct chemical environments surrounding the Fe atoms in the two compounds. Ga substitution favors the Sm–Ga bonding formation while avoiding Ga–C interactions. Doped Ga atoms result in more negative formation energy in Sm2(Fe, Ga)17C3, indicating improved structural stability. Crystal Orbital Hamilton Population analysis reveals that carbon insertion weakens the bonding of Sm-Fe (18h) and Sm-Fe (18f) in Sm2Fe17C3. Ga doping facilitates electron redistribution across chemical bonds, thereby reinforcing Fe(18h)–Sm and Fe(18f)–Sm interactions and stabilizing the carbon-centered octahedral local structure. This synergistic effect contributes significantly to the observed enhancement in phase stability of Sm2(Fe, Ga)17Cx. These findings suggest that chemical bond engineering through the selective doping of Ga can enhance phase stability and facilitate the synthesis of Sm2Fe17C3, providing a viable strategy for developing advanced magnets.

Liu, Xubo [Critical Materials Innovation Hub, Divi↗