Materials Data on Ta2NiSe7 by Materials Project

Abstract

Ta2NiSe7 crystallizes in the monoclinic C2/m space group. The structure is two-dimensional and consists of two Ta2NiSe7 sheets oriented in the (1, 0, 0) direction. there are two inequivalent Ta5+ sites. In the first Ta5+ site, Ta5+ is bonded in a 8-coordinate geometry to eight Se2- atoms. There are a spread of Ta–Se bond distances ranging from 2.62–2.77 Å. In the second Ta5+ site, Ta5+ is bonded to six Se2- atoms to form TaSe6 octahedra that share edges with two equivalent NiSe6 octahedra and edges with four equivalent TaSe6 octahedra. There are a spread of Ta–Se bond distances ranging from 2.50–2.76 Å. Ni4+ is bonded to six Se2- atoms to form distorted NiSe6 octahedra that share edges with two equivalent TaSe6 octahedra and edges with two equivalent NiSe6 octahedra. There are a spread of Ni–Se bond distances ranging from 2.42–2.72 Å. There are seven inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 3-coordinate geometry to three equivalent Ta5+ atoms. In the second Se2- site, Se2- is bonded in a 3-coordinate geometry to two equivalent Ta5+ and one Ni4+ atom. In the third Se2- site, Se2- is bonded in a distorted T-shaped geometry to one Ta5+ and two equivalent Ni4+ atoms. In the fourth Se2- site, Se2- is bonded in a distorted T-shaped geometry to two equivalent Ta5+ and one Ni4+ atom. In the fifth Se2- site, Se2- is bonded in a distorted L-shaped geometry to two equivalent Ta5+ atoms. In the sixth Se2- site, Se2- is bonded in a distorted trigonal non-coplanar geometry to three equivalent Ta5+ atoms. In the seventh Se2- site, Se2- is bonded in a distorted trigonal non-coplanar geometry to one Ta5+ and two equivalent Ni4+ atoms.