DOE OSTI2020
NbWSe4(NbSe2)2 is Molybdenite-derived structured and crystallizes in the monoclinic Cm space group. The structure is two-dimensional and consists of two NbSe2 sheets oriented in the (1, 0, 0) direction and two NbWSe4 sheets oriented in the (1, 0, 0) direction. In each NbSe2 sheet, Nb+4.67+ 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 2.61–2.63 Å. There are four inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 3-coordinate geometry to three equivalent Nb+4.67+ atoms. In the second Se2- site, Se2- is bonded in a 3-coordinate geometry to three equivalent Nb+4.67+ atoms. In the third Se2- site, Se2- is bonded in a 3-coordinate geometry to three equivalent Nb+4.67+ atoms. In the fourth Se2- site, Se2- is bonded in a 3-coordinate geometry to three equivalent Nb+4.67+ atoms. In each NbWSe4 sheet, Nb+4.67+ is bonded to six Se2- atoms to form distorted NbSe6 pentagonal pyramids that share edges with two equivalent NbSe6 pentagonal pyramids and edges with four equivalent WSe6 pentagonal pyramids. There are four shorter (2.61 Å) and two longer (2.64 Å) Nb–Se bond lengths. W2+ is bonded to six Se2- atoms to form distorted WSe6 pentagonal pyramids that share edges with two equivalent WSe6 pentagonal pyramids and edges with four equivalent NbSe6 pentagonal pyramids. There are two shorter (2.56 Å) and four longer (2.59 Å) W–Se bond lengths. There are four inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 3-coordinate geometry to two equivalent Nb+4.67+ and one W2+ atom. In the second Se2- site, Se2- is bonded in a 3-coordinate geometry to one Nb+4.67+ and two equivalent W2+ atoms. In the third Se2- site, Se2- is bonded in a 3-coordinate geometry to one Nb+4.67+ and two equivalent W2+ atoms. In the fourth Se2- site, Se2- is bonded in a 3-coordinate geometry to two equivalent Nb+4.67+ and one W2+ atom.