DOI: 10.17188/1306801
title: Materials Data on Na2Ge2O5 by Materials Project

description: Na2Ge2O5 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are four inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded to five O2- atoms to form distorted NaO5 square pyramids that share corners with four equivalent NaO5 square pyramids, corners with four GeO4 tetrahedra, and an edgeedge with one GeO4 tetrahedra. There are a spread of Na–O bond distances ranging from 2.40–2.70 Å. In the second Na1+ site, Na1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Na–O bond distances ranging from 2.37–2.89 Å. In the third Na1+ site, Na1+ is bonded to five O2- atoms to form distorted NaO5 trigonal bipyramids that share corners with two equivalent NaO6 octahedra, corners with four GeO4 tetrahedra, corners with two equivalent NaO5 trigonal bipyramids, edges with two equivalent NaO6 octahedra, an edgeedge with one GeO4 tetrahedra, and edges with two equivalent NaO5 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 26–68°. There are a spread of Na–O bond distances ranging from 2.33–2.73 Å. In the fourth Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share corners with two equivalent NaO6 octahedra, corners with four GeO4 tetrahedra, corners with two equivalent NaO5 trigonal bipyramids, edges with two equivalent NaO6 octahedra, edges with two equivalent GeO4 tetrahedra, and edges with two equivalent NaO5 trigonal bipyramids. The corner-sharing octahedral tilt angles are 19°. There are a spread of Na–O bond distances ranging from 2.39–2.71 Å. There are four inequivalent Ge4+ sites. In the first Ge4+ site, Ge4+ is bonded to four O2- atoms to form GeO4 tetrahedra that share a cornercorner with one NaO6 octahedra, a cornercorner with one NaO5 square pyramid, corners with three GeO4 tetrahedra, a cornercorner with one NaO5 trigonal bipyramid, and edges with two equivalent NaO6 octahedra. The corner-sharing octahedral tilt angles are 68°. There are a spread of Ge–O bond distances ranging from 1.72–1.80 Å. In the second Ge4+ site, Ge4+ is bonded to four O2- atoms to form GeO4 tetrahedra that share a cornercorner with one NaO6 octahedra, corners with three GeO4 tetrahedra, corners with two equivalent NaO5 trigonal bipyramids, and an edgeedge with one NaO5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 54°. There are a spread of Ge–O bond distances ranging from 1.73–1.81 Å. In the third Ge4+ site, Ge4+ is bonded to four O2- atoms to form GeO4 tetrahedra that share a cornercorner with one NaO6 octahedra, corners with two equivalent NaO5 square pyramids, corners with three GeO4 tetrahedra, and a cornercorner with one NaO5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 40°. There are a spread of Ge–O bond distances ranging from 1.73–1.81 Å. In the fourth Ge4+ site, Ge4+ is bonded to four O2- atoms to form GeO4 tetrahedra that share a cornercorner with one NaO6 octahedra, a cornercorner with one NaO5 square pyramid, corners with three GeO4 tetrahedra, and an edgeedge with one NaO5 square pyramid. The corner-sharing octahedral tilt angles are 57°. There are a spread of Ge–O bond distances ranging from 1.72–1.81 Å. There are ten inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to one Na1+ and two Ge4+ atoms. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to one Na1+ and two Ge4+ atoms. In the third O2- site, O2- is bonded to four Na1+ and one Ge4+ atom to form a mixture of distorted edge and corner-sharing ONa4Ge trigonal bipyramids. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+ and two Ge4+ atoms. In the fifth O2- site, O2- is bonded in a 5-coordinate geometry to four Na1+ and one Ge4+ atom. In the sixth O2- site, O2- is bonded to four Na1+ and one Ge4+ atom to form a mixture of distorted edge and corner-sharing ONa4Ge trigonal bipyramids. In the seventh O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Na1+ and two Ge4+ atoms. In the eighth O2- site, O2- is bonded in a 5-coordinate geometry to four Na1+ and one Ge4+ atom. In the ninth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Na1+ and two Ge4+ atoms. In the tenth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Na1+ and two Ge4+ atoms.