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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on TbFe2 by Materials Project

TbFe2 is Cubic Laves structured and crystallizes in the trigonal R-3m space group. The structure is three-dimensional. Tb is bonded in a 12-coordinate geometry to twelve Fe atoms. There are nine shorter (3.02 Å) and three longer (3.04 Å) Tb–Fe bond lengths. There are two inequivalent Fe sites. In the first Fe site, Fe is bonded to six equivalent Tb and six equivalent Fe atoms to form a mixture of edge, corner, and face-sharing FeTb6Fe6 cuboctahedra. All Fe–Fe bond lengths are 2.59 Å. In the second Fe site, Fe is bonded to six equivalent Tb and six Fe atoms to form a mixture of edge, corner, and face-sharing FeTb6Fe6 cuboctahedra. All Fe–Fe bond lengths are 2.58 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Materials Data on TbFe2 by Materials Project

TbFe2 is Hexagonal Laves structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Tb is bonded in a 12-coordinate geometry to twelve Fe atoms. There are nine shorter (3.04 Å) and three longer (3.05 Å) Tb–Fe bond lengths. There are two inequivalent Fe sites. In the first Fe site, Fe is bonded to six equivalent Tb and six equivalent Fe atoms to form a mixture of corner, edge, and face-sharing FeTb6Fe6 cuboctahedra. All Fe–Fe bond lengths are 2.57 Å. In the second Fe site, Fe is bonded to six equivalent Tb and six Fe atoms to form a mixture of corner, edge, and face-sharing FeTb6Fe6 cuboctahedra. There are two shorter (2.57 Å) and two longer (2.62 Å) Fe–Fe bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Materials Data on TbFe2 by Materials Project

TbFe2 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. Tb is bonded in a distorted square co-planar geometry to four Fe atoms. There are a spread of Tb–Fe bond distances ranging from 2.60–2.63 Å. There are three inequivalent Fe sites. In the first Fe site, Fe is bonded in a distorted linear geometry to two equivalent Tb atoms. In the second Fe site, Fe is bonded in a distorted linear geometry to two equivalent Tb atoms. In the third Fe site, Fe is bonded in a distorted linear geometry to two equivalent Tb atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Rhombohedral Distortion of the Cubic MgCu2-Type Structure in Ca2Pt3Ga and Ca2Pd3Ga

Two new fully ordered ternary Laves phase compounds, Ca2Pt3Ga and Ca2Pd3Ga, have been synthesized and characterized by powder and single-crystal X-ray diffraction along with electronic structure calculations. Ca2Pd3Ga was synthesized as a pure phase whereas Ca2Pt3Ga was found as a diphasic product with Ca2Pt2Ga. Electronic structure calculations were performed to try and understand why CaPt2 and CaPd2, which crystalize in the cubic MgCu2-type Laves phase structure, distort to the ordered rhombohedral variant, first observed in the magneto-restricted TbFe2 compound, with the substitution of twenty-five percent of the Pt/Pd with Ga. Electronic stability was investigated by changing the valence electron count from 22e−/f.u. in CaPd2 and CaPt2 (2x) to 37e−/f.u. in Ca2Pd3Ga and Ca2Pt3Ga, which causes the Fermi level to shift to a more energetically favorable location in the DOS. The coloring problem was studied by placing a single Ga atom in each of four tetrahedra of the cubic unit cell of the MgCu2-type structure, with nine symmetrically inequivalent models being investigated. Non-optimized and optimized total energy analyses of structural characteristics, along with electronic properties, will be discussed.

36 MATERIALS SCIENCE↗