Materials Data on Ta24Ti5Se48 by Materials Project
Ti5Ta24Se48 crystallizes in the trigonal R-3 space group. The structure is three-dimensional. there are three inequivalent Ti4+ sites. In the first Ti4+ site, Ti4+ is bonded to six Se2- atoms to form TiSe6 octahedra that share corners with twelve TaSe6 pentagonal pyramids and a faceface with one TaSe6 pentagonal pyramid. There are three shorter (2.52 Å) and three longer (2.68 Å) Ti–Se bond lengths. In the second Ti4+ site, Ti4+ is bonded in a distorted trigonal non-coplanar geometry to three equivalent Se2- atoms. All Ti–Se bond lengths are 2.46 Å. In the third Ti4+ site, Ti4+ is bonded to six equivalent Se2- atoms to form TiSe6 octahedra that share corners with twelve TaSe6 pentagonal pyramids and faces with two equivalent TaSe6 pentagonal pyramids. All Ti–Se bond lengths are 2.57 Å. There are six inequivalent Ta+3.17+ sites. In the first Ta+3.17+ site, Ta+3.17+ is bonded to six Se2- atoms to form distorted TaSe6 pentagonal pyramids that share a cornercorner with one TiSe6 octahedra, corners with two equivalent TaSe6 octahedra, and edges with four TaSe6 pentagonal pyramids. The corner-sharing octahedra tilt angles range from 47–50°. There are a spread of Ta–Se bond distances ranging from 2.62–2.67 Å. In the second Ta+3.17+ site, Ta+3.17+ is bonded to six Se2- atoms to form corner-sharing TaSe6 octahedra. There are three shorter (2.51 Å) and three longer (2.76 Å) Ta–Se bond lengths. In the third Ta+3.17+ site, Ta+3.17+ is bonded to six Se2- atoms to form distorted TaSe6 pentagonal pyramids that share a cornercorner with one TaSe6 octahedra, corners with three TiSe6 octahedra, and edges with five TaSe6 pentagonal pyramids. The corner-sharing octahedra tilt angles range from 46–50°. There are a spread of Ta–Se bond distances ranging from 2.58–2.66 Å. In the fourth Ta+3.17+ site, Ta+3.17+ is bonded to six Se2- atoms to form distorted TaSe6 pentagonal pyramids that share a cornercorner with one TaSe6 octahedra, corners with two TiSe6 octahedra, and edges with five TaSe6 pentagonal pyramids. The corner-sharing octahedra tilt angles range from 44–47°. There are a spread of Ta–Se bond distances ranging from 2.61–2.70 Å. In the fifth Ta+3.17+ site, Ta+3.17+ is bonded to six Se2- atoms to form distorted TaSe6 pentagonal pyramids that share edges with six TaSe6 pentagonal pyramids and faces with two TiSe6 octahedra. There are three shorter (2.62 Å) and three longer (2.63 Å) Ta–Se bond lengths. In the sixth Ta+3.17+ site, Ta+3.17+ is bonded in a trigonal planar geometry to three equivalent Se2- atoms. All Ta–Se bond lengths are 2.45 Å. There are eight inequivalent Se2- sites. In the first Se2- site, Se2- is bonded to one Ti4+ and three Ta+3.17+ atoms to form a mixture of distorted edge, face, and corner-sharing SeTa3Ti trigonal pyramids. In the second Se2- site, Se2- is bonded in a distorted rectangular see-saw-like geometry to one Ti4+ and three Ta+3.17+ atoms. In the third Se2- site, Se2- is bonded in a 3-coordinate geometry to three Ta+3.17+ atoms. In the fourth Se2- site, Se2- is bonded in a 3-coordinate geometry to three Ta+3.17+ atoms. In the fifth Se2- site, Se2- is bonded in a 3-coordinate geometry to three Ta+3.17+ atoms. In the sixth Se2- site, Se2- is bonded in a 3-coordinate geometry to three Ta+3.17+ atoms. In the seventh Se2- site, Se2- is bonded to one Ti4+ and three Ta+3.17+ atoms to form a mixture of distorted edge, face, and corner-sharing SeTa3Ti trigonal pyramids. In the eighth Se2- site, Se2- is bonded in a 3-coordinate geometry to one Ti4+ and two Ta+3.17+ atoms.