Materials Data on Ta4CrSe8 by Materials Project

Abstract

Ta4CrSe8 crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. there are two inequivalent Ta+3.50+ sites. In the first Ta+3.50+ site, Ta+3.50+ is bonded to six equivalent Se2- atoms to form distorted TaSe6 pentagonal pyramids that share edges with six equivalent TaSe6 pentagonal pyramids and faces with two equivalent CrSe6 octahedra. All Ta–Se bond lengths are 2.60 Å. In the second Ta+3.50+ site, Ta+3.50+ is bonded to six Se2- atoms to form distorted TaSe6 pentagonal pyramids that share corners with four equivalent CrSe6 octahedra and edges with six TaSe6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 47°. There are two shorter (2.58 Å) and four longer (2.63 Å) Ta–Se bond lengths. Cr2+ is bonded to six equivalent Se2- atoms to form CrSe6 octahedra that share corners with twelve equivalent TaSe6 pentagonal pyramids and faces with two equivalent TaSe6 pentagonal pyramids. All Cr–Se bond lengths are 2.48 Å. There are two inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 3-coordinate geometry to three equivalent Ta+3.50+ atoms. In the second Se2- site, Se2- is bonded to three Ta+3.50+ and one Cr2+ atom to form a mixture of distorted face, edge, and corner-sharing SeTa3Cr trigonal pyramids.