DOE OSTI2020
K2(NbSe2)3 crystallizes in the orthorhombic Amm2 space group. The structure is three-dimensional. there are two inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 6-coordinate geometry to six Se2- atoms. All K–Se bond lengths are 3.27 Å. In the second K1+ site, K1+ is bonded in a 6-coordinate geometry to six Se2- atoms. All K–Se bond lengths are 3.27 Å. There are two inequivalent Nb+3.33+ sites. In the first Nb+3.33+ site, Nb+3.33+ is bonded to six Se2- atoms to form distorted edge-sharing NbSe6 pentagonal pyramids. There are two shorter (2.63 Å) and four longer (2.64 Å) Nb–Se bond lengths. In the second Nb+3.33+ site, Nb+3.33+ is bonded to six Se2- atoms to form distorted edge-sharing NbSe6 pentagonal pyramids. There are a spread of Nb–Se bond distances ranging from 2.62–2.64 Å. There are four inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 5-coordinate geometry to two equivalent K1+ and three Nb+3.33+ atoms. In the second Se2- site, Se2- is bonded in a 5-coordinate geometry to two equivalent K1+ and three Nb+3.33+ atoms. In the third Se2- site, Se2- is bonded to two equivalent K1+ and three Nb+3.33+ atoms to form a mixture of distorted edge and corner-sharing SeK2Nb3 square pyramids. In the fourth Se2- site, Se2- is bonded to two equivalent K1+ and three Nb+3.33+ atoms to form a mixture of distorted edge and corner-sharing SeK2Nb3 square pyramids.