Materials Data on Na2Zn2Se3 by Materials Project
Na2Zn2Se3 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. there are three inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded to six Se2- atoms to form NaSe6 octahedra that share corners with six ZnSe4 tetrahedra, corners with six equivalent NaSe5 trigonal bipyramids, edges with five NaSe6 octahedra, and edges with six ZnSe4 tetrahedra. There are a spread of Na–Se bond distances ranging from 3.02–3.14 Å. In the second Na1+ site, Na1+ is bonded to six Se2- atoms to form NaSe6 octahedra that share corners with eight ZnSe4 tetrahedra, corners with four equivalent NaSe5 trigonal bipyramids, edges with three equivalent NaSe6 octahedra, edges with four ZnSe4 tetrahedra, and faces with two equivalent NaSe5 trigonal bipyramids. There are a spread of Na–Se bond distances ranging from 3.04–3.14 Å. In the third Na1+ site, Na1+ is bonded to five Se2- atoms to form distorted NaSe5 trigonal bipyramids that share corners with five NaSe6 octahedra, corners with six ZnSe4 tetrahedra, corners with two equivalent NaSe5 trigonal bipyramids, edges with three ZnSe4 tetrahedra, edges with two equivalent NaSe5 trigonal bipyramids, and a faceface with one NaSe6 octahedra. The corner-sharing octahedra tilt angles range from 38–55°. There are a spread of Na–Se bond distances ranging from 2.86–3.43 Å. There are two inequivalent Zn2+ sites. In the first Zn2+ site, Zn2+ is bonded to four Se2- atoms to form ZnSe4 tetrahedra that share corners with three NaSe6 octahedra, corners with five ZnSe4 tetrahedra, corners with two equivalent NaSe5 trigonal bipyramids, edges with three NaSe6 octahedra, an edgeedge with one ZnSe4 tetrahedra, and edges with two equivalent NaSe5 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 21–50°. There are a spread of Zn–Se bond distances ranging from 2.48–2.55 Å. In the second Zn2+ site, Zn2+ is bonded to four Se2- atoms to form ZnSe4 tetrahedra that share corners with four NaSe6 octahedra, corners with three equivalent ZnSe4 tetrahedra, corners with four equivalent NaSe5 trigonal bipyramids, edges with two NaSe6 octahedra, edges with two ZnSe4 tetrahedra, and an edgeedge with one NaSe5 trigonal bipyramid. The corner-sharing octahedra tilt angles range from 23–55°. There are a spread of Zn–Se bond distances ranging from 2.47–2.56 Å. There are three inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 7-coordinate geometry to four Na1+ and three Zn2+ atoms. In the second Se2- site, Se2- is bonded to three Na1+ and three Zn2+ atoms to form a mixture of distorted edge and corner-sharing SeNa3Zn3 pentagonal pyramids. In the third Se2- site, Se2- is bonded to four Na1+ and two Zn2+ atoms to form a mixture of distorted edge, face, and corner-sharing SeNa4Zn2 pentagonal pyramids.