SEARCH · Engineering Papers
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.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Ta2Co is Khatyrkite structured and crystallizes in the tetragonal I4/mcm space group. The structure is three-dimensional. Ta is bonded in a 4-coordinate geometry to four equivalent Co atoms. All Ta–Co bond lengths are 2.62 Å. Co is bonded in a 10-coordinate geometry to eight equivalent Ta and two equivalent Co atoms. Both Co–Co bond lengths are 2.49 Å.
TaReCoSe4TaSe2ReSe2 crystallizes in the trigonal P3m1 space group. The structure is two-dimensional and consists of one ReSe2 sheet oriented in the (0, 0, 1) direction; one TaReCoSe4 sheet oriented in the (0, 0, 1) direction; and one TaSe2 sheet oriented in the (0, 0, 1) direction. In the ReSe2 sheet, Re3+ is bonded to six Se2- atoms to form distorted edge-sharing ReSe6 pentagonal pyramids. All Re–Se bond lengths are 2.54 Å. There are two inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 3-coordinate geometry to three equivalent Re3+ atoms. In the second Se2- site, Se2- is bonded in a 3-coordinate geometry to three equivalent Re3+ atoms. In the TaReCoSe4 sheet, Ta4+ is bonded to six Se2- atoms to form distorted TaSe6 pentagonal pyramids that share corners with six equivalent CoSe6 octahedra, edges with six equivalent TaSe6 pentagonal pyramids, and a faceface with one CoSe6 octahedra. The corner-sharing octahedral tilt angles are 46°. There are three shorter (2.61 Å) and three longer (2.63 Å) Ta–Se bond lengths. Re3+ is bonded to six Se2- atoms to form distorted ReSe6 pentagonal pyramids that share corners with six equivalent CoSe6 octahedra, edges with six equivalent ReSe6 pentagonal pyramids, and a faceface with one CoSe6 octahedra. The corner-sharing octahedral tilt angles are 48°. There are three shorter (2.52 Å) and three longer (2.59 Å) Re–Se bond lengths. Co2+ is bonded to six Se2- atoms to form CoSe6 octahedra that share corners with six equivalent TaSe6 pentagonal pyramids, corners with six equivalent ReSe6 pentagonal pyramids, edges with six equivalent CoSe6 octahedra, a faceface with one TaSe6 pentagonal pyramid, and a faceface with one ReSe6 pentagonal pyramid. There are three shorter (2.37 Å) and three longer (2.49 Å) Co–Se bond lengths. There are four inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 6-coordinate geometry to three equivalent Re3+ and three equivalent Co2+ atoms. In the second Se2- site, Se2- is bonded to three equivalent Ta4+ and three equivalent Co2+ atoms to form distorted edge-sharing SeTa3Co3 pentagonal pyramids. In the third Se2- site, Se2- is bonded in a 3-coordinate geometry to three equivalent Ta4+ atoms. In the fourth Se2- site, Se2- is bonded in a distorted T-shaped geometry to three equivalent Re3+ atoms. In the TaSe2 sheet, Ta4+ is bonded to six equivalent Se2- atoms to form distorted edge-sharing TaSe6 pentagonal pyramids. All Ta–Se bond lengths are 2.61 Å. Se2- is bonded in a 3-coordinate geometry to three equivalent Ta4+ atoms.