Materials Data on Na4GeSe4 by Materials Project

Abstract

Na4GeSe4 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. there are five inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded to six Se2- atoms to form distorted NaSe6 octahedra that share corners with four GeSe4 tetrahedra, corners with two equivalent NaSe4 trigonal pyramids, edges with six NaSe5 square pyramids, an edgeedge with one GeSe4 tetrahedra, and edges with two equivalent NaSe4 trigonal pyramids. There are a spread of Na–Se bond distances ranging from 3.02–3.23 Å. In the second Na1+ site, Na1+ is bonded to five Se2- atoms to form distorted NaSe5 square pyramids that share corners with four equivalent NaSe5 square pyramids, corners with three equivalent GeSe4 tetrahedra, corners with two equivalent NaSe4 trigonal pyramids, edges with two equivalent NaSe6 octahedra, an edgeedge with one GeSe4 tetrahedra, and edges with two equivalent NaSe4 trigonal pyramids. There are three shorter (2.99 Å) and two longer (3.25 Å) Na–Se bond lengths. In the third Na1+ site, Na1+ is bonded in a 5-coordinate geometry to five Se2- atoms. There are a spread of Na–Se bond distances ranging from 2.93–3.36 Å. In the fourth Na1+ site, Na1+ is bonded to four Se2- atoms to form distorted NaSe4 trigonal pyramids that share a cornercorner with one NaSe6 octahedra, corners with five NaSe5 square pyramids, corners with two equivalent GeSe4 tetrahedra, corners with two equivalent NaSe4 trigonal pyramids, an edgeedge with one NaSe6 octahedra, an edgeedge with one NaSe5 square pyramid, an edgeedge with one GeSe4 tetrahedra, and an edgeedge with one NaSe4 trigonal pyramid. The corner-sharing octahedral tilt angles are 24°. There are a spread of Na–Se bond distances ranging from 2.91–2.97 Å. In the fifth Na1+ site, Na1+ is bonded to five Se2- atoms to form distorted NaSe5 square pyramids that share corners with three NaSe5 square pyramids, a cornercorner with one GeSe4 tetrahedra, corners with four equivalent NaSe4 trigonal pyramids, edges with two equivalent NaSe6 octahedra, an edgeedge with one NaSe5 square pyramid, and edges with two GeSe4 tetrahedra. There are a spread of Na–Se bond distances ranging from 2.94–3.43 Å. There are two inequivalent Ge4+ sites. In the first Ge4+ site, Ge4+ is bonded to four Se2- atoms to form GeSe4 tetrahedra that share corners with three equivalent NaSe6 octahedra, corners with two equivalent NaSe5 square pyramids, and edges with three NaSe5 square pyramids. The corner-sharing octahedra tilt angles range from 9–66°. There are a spread of Ge–Se bond distances ranging from 2.38–2.41 Å. In the second Ge4+ site, Ge4+ is bonded to four Se2- atoms to form GeSe4 tetrahedra that share a cornercorner with one NaSe6 octahedra, corners with three equivalent NaSe5 square pyramids, corners with four equivalent NaSe4 trigonal pyramids, an edgeedge with one NaSe6 octahedra, edges with two equivalent NaSe5 square pyramids, and edges with two equivalent NaSe4 trigonal pyramids. The corner-sharing octahedral tilt angles are 1°. There are a spread of Ge–Se bond distances ranging from 2.38–2.40 Å. There are six inequivalent Se2- sites. In the first Se2- site, Se2- is bonded to five Na1+ and one Ge4+ atom to form distorted SeNa5Ge octahedra that share corners with five SeNa5Ge octahedra, a cornercorner with one SeNa4Ge trigonal bipyramid, and edges with five SeNa5Ge octahedra. The corner-sharing octahedra tilt angles range from 17–59°. In the second Se2- site, Se2- is bonded in a 8-coordinate geometry to seven Na1+ and one Ge4+ atom. In the third Se2- site, Se2- is bonded to four Na1+ and one Ge4+ atom to form a mixture of distorted edge and corner-sharing SeNa4Ge trigonal bipyramids. The corner-sharing octahedra tilt angles range from 12–81°. In the fourth Se2- site, Se2- is bonded to five Na1+ and one Ge4+ atom to form distorted SeNa5Ge octahedra that share corners with six SeNa5Ge octahedra, corners with two equivalent SeNa4Ge trigonal bipyramids, edges with three SeNa5Ge octahedra, and an edgeedge with one SeNa4Ge trigonal bipyramid. The corner-sharing octahedra tilt angles range from 17–57°. In the fifth Se2- site, Se2- is bonded in a distorted see-saw-like geometry to three Na1+ and one Ge4+ atom. In the sixth Se2- site, Se2- is bonded to five Na1+ and one Ge4+ atom to form SeNa5Ge octahedra that share corners with two equivalent SeNa5Ge octahedra, corners with two equivalent SeNa4Ge trigonal bipyramids, and edges with six SeNa5Ge octahedra. The corner-sharing octahedral tilt angles are 29°.