Materials Data on K2(TaSe2)3 by Materials Project
K3(TaSe2)4K(TaSe2)2 crystallizes in the hexagonal P-6m2 space group. The structure is two-dimensional and consists of one K(TaSe2)2 sheet oriented in the (0, 0, 1) direction and one K3(TaSe2)4 sheet oriented in the (0, 0, 1) direction. In the K(TaSe2)2 sheet, K1+ is bonded in a 12-coordinate geometry to six equivalent Se2- atoms. All K–Se bond lengths are 3.21 Å. Ta+3.33+ is bonded to six Se2- atoms to form distorted edge-sharing TaSe6 pentagonal pyramids. There are three shorter (2.62 Å) and three longer (2.64 Å) Ta–Se bond lengths. There are two inequivalent Se2- sites. In the first Se2- site, Se2- is bonded to three equivalent K1+ and three equivalent Ta+3.33+ atoms to form a mixture of distorted corner, edge, and face-sharing SeK3Ta3 octahedra. The corner-sharing octahedral tilt angles are 38°. In the second Se2- site, Se2- is bonded in a distorted T-shaped geometry to three equivalent Ta+3.33+ atoms. In the K3(TaSe2)4 sheet, there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 12-coordinate geometry to six Se2- atoms. There are three shorter (3.20 Å) and three longer (3.22 Å) K–Se bond lengths. In the second K1+ site, K1+ is bonded in a 12-coordinate geometry to six equivalent Se2- atoms. All K–Se bond lengths are 3.22 Å. There are two inequivalent Ta+3.33+ sites. In the first Ta+3.33+ site, Ta+3.33+ is bonded to six Se2- atoms to form distorted edge-sharing TaSe6 pentagonal pyramids. There are three shorter (2.62 Å) and three longer (2.64 Å) Ta–Se bond lengths. In the second Ta+3.33+ site, Ta+3.33+ is bonded to six Se2- atoms to form distorted edge-sharing TaSe6 pentagonal pyramids. All Ta–Se bond lengths are 2.63 Å. There are four inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a distorted T-shaped geometry to three equivalent Ta+3.33+ atoms. In the second Se2- site, Se2- is bonded in a 6-coordinate geometry to three equivalent K1+ and three equivalent Ta+3.33+ atoms. In the third Se2- site, Se2- is bonded to three equivalent K1+ and three equivalent Ta+3.33+ atoms to form a mixture of distorted corner, edge, and face-sharing SeK3Ta3 octahedra. The corner-sharing octahedral tilt angles are 37°. In the fourth Se2- site, Se2- is bonded to three equivalent K1+ and three equivalent Ta+3.33+ atoms to form a mixture of distorted corner, edge, and face-sharing SeK3Ta3 octahedra. The corner-sharing octahedral tilt angles are 37°.