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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Na2Ge2O5 by Materials Project

Na2Ge2O5 crystallizes in the orthorhombic Pna2_1 space group. The structure is three-dimensional. there are two 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 2.40–2.69 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 2.35–2.80 Å. There are two inequivalent Ge4+ sites. In the first Ge4+ site, Ge4+ is bonded to four O2- atoms to form GeO4 tetrahedra that share corners with two equivalent NaO5 square pyramids, corners with three GeO4 tetrahedra, and an edgeedge with one NaO5 square pyramid. There are a spread of Ge–O bond distances ranging from 1.71–1.81 Å. In the second Ge4+ site, Ge4+ is bonded to four O2- atoms to form GeO4 tetrahedra that share corners with two equivalent NaO5 square pyramids and corners with three GeO4 tetrahedra. There are a spread of Ge–O bond distances ranging from 1.72–1.81 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded in a 5-coordinate geometry to four Na1+ and one Ge4+ atom. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to one Na1+ and two equivalent Ge4+ atoms. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to one Na1+ and two equivalent Ge4+ atoms. In the fourth O2- site, O2- is bonded to four Na1+ and one Ge4+ atom to form distorted corner-sharing ONa4Ge trigonal bipyramids. In the fifth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Na1+ and two Ge4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na2Ge2O5 by Materials Project

Na2Ge2O5 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are two inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded to five O2- atoms to form distorted NaO5 trigonal bipyramids that share corners with four GeO4 tetrahedra, corners with four NaO5 trigonal bipyramids, an edgeedge with one GeO4 tetrahedra, and edges with four NaO5 trigonal bipyramids. There are a spread of Na–O bond distances ranging from 2.39–2.70 Å. In the second Na1+ site, Na1+ is bonded to five O2- atoms to form distorted NaO5 trigonal bipyramids that share corners with four GeO4 tetrahedra, corners with four NaO5 trigonal bipyramids, an edgeedge with one GeO4 tetrahedra, and edges with four NaO5 trigonal bipyramids. There are a spread of Na–O bond distances ranging from 2.39–2.71 Å. There are two inequivalent Ge4+ sites. In the first Ge4+ site, Ge4+ is bonded to four O2- atoms to form GeO4 tetrahedra that share corners with three equivalent GeO4 tetrahedra, corners with four NaO5 trigonal bipyramids, and an edgeedge with one NaO5 trigonal bipyramid. There are a spread of Ge–O bond distances ranging from 1.73–1.80 Å. In the second Ge4+ site, Ge4+ is bonded to four O2- atoms to form GeO4 tetrahedra that share corners with three equivalent GeO4 tetrahedra, corners with four NaO5 trigonal bipyramids, and an edgeedge with one NaO5 trigonal bipyramid. There are a spread of Ge–O bond distances ranging from 1.72–1.81 Å. There are five 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 to four Na1+ and one Ge4+ atom to form a mixture of distorted edge and corner-sharing ONa4Ge trigonal bipyramids. 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 distorted trigonal planar geometry to one Na1+ and two Ge4+ atoms. In the fifth O2- site, O2- is bonded in a bent 150 degrees geometry to two Ge4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na2Ge2O5 by Materials Project

Na2Ge2O5 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are two inequivalent Na1+ sites. In the first 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 18°. There are a spread of Na–O bond distances ranging from 2.37–2.73 Å. In the second 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 24–69°. There are a spread of Na–O bond distances ranging from 2.34–2.76 Å. There are two inequivalent Ge4+ sites. In the first Ge4+ site, Ge4+ is bonded to four O2- atoms to form GeO4 tetrahedra that share corners with two equivalent NaO6 octahedra, corners with three GeO4 tetrahedra, corners with three equivalent NaO5 trigonal bipyramids, and an edgeedge with one NaO5 trigonal bipyramid. The corner-sharing octahedra tilt angles range from 39–55°. There are a spread of Ge–O bond distances ranging from 1.73–1.81 Å. In the second Ge4+ site, Ge4+ is bonded to four O2- atoms to form GeO4 tetrahedra that share corners with two equivalent NaO6 octahedra, corners with three GeO4 tetrahedra, a cornercorner with one NaO5 trigonal bipyramid, and edges with two equivalent NaO6 octahedra. The corner-sharing octahedra tilt angles range from 57–68°. There are a spread of Ge–O bond distances ranging from 1.72–1.81 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded in a 5-coordinate geometry to four Na1+ and one Ge4+ atom. In the second O2- site, O2- is bonded in a 5-coordinate geometry to four Na1+ and one Ge4+ atom. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to one Na1+ and two equivalent Ge4+ atoms. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Na1+ and two equivalent Ge4+ atoms. In the fifth O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+ and two Ge4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na2Ge2O5 by Materials Project

Na2Ge2O5 crystallizes in the orthorhombic Pca2_1 space group. The structure is three-dimensional. there are two inequivalent Na1+ sites. In the first 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 2.41–2.85 Å. In the second Na1+ site, Na1+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Na–O bond distances ranging from 2.40–2.98 Å. There are two inequivalent Ge4+ sites. In the first Ge4+ site, Ge4+ is bonded to four O2- atoms to form corner-sharing GeO4 tetrahedra. There are a spread of Ge–O bond distances ranging from 1.71–1.82 Å. In the second Ge4+ site, Ge4+ is bonded to four O2- atoms to form corner-sharing GeO4 tetrahedra. There are a spread of Ge–O bond distances ranging from 1.71–1.82 Å. There are five inequivalent O2- sites. In the first O2- site, O2- is bonded in a 5-coordinate geometry to four Na1+ and one Ge4+ atom. In the second O2- site, O2- is bonded in a 4-coordinate geometry to four Na1+ and one Ge4+ atom. In the third O2- site, O2- is bonded in a distorted bent 120 degrees geometry to two Na1+ and two Ge4+ atoms. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to two Na1+ and two Ge4+ atoms. In the fifth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Na1+ and two Ge4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na2Ge2O5 by Materials Project

Na2Ge2O5 crystallizes in the orthorhombic Pbcn space group. The structure is three-dimensional. Na1+ is bonded to five O2- atoms to form distorted NaO5 trigonal bipyramids that share corners with four equivalent GeO4 tetrahedra, corners with four equivalent NaO5 trigonal bipyramids, an edgeedge with one GeO4 tetrahedra, and edges with four equivalent NaO5 trigonal bipyramids. There are a spread of Na–O bond distances ranging from 2.30–2.78 Å. Ge4+ is bonded to four O2- atoms to form GeO4 tetrahedra that share corners with three equivalent GeO4 tetrahedra, corners with four equivalent NaO5 trigonal bipyramids, and an edgeedge with one NaO5 trigonal bipyramid. There are a spread of Ge–O bond distances ranging from 1.73–1.81 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent Ge4+ atoms. In the second O2- site, O2- is bonded in a 5-coordinate geometry to four equivalent Na1+ and one Ge4+ atom. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to one Na1+ and two equivalent Ge4+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na2Ge2O5 by Materials Project

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.

36 MATERIALS SCIENCE↗
NASA NTRS1992

Pressure-induced coordination changes in alkali-germanate melts - An in situ spectroscopic investigation

The structure of liquid Na2Ge2O5-H2O, a silicate melt analog, has been studied with Raman spectroscopy to pressures of 2.2 gigapascals. Upon compression, a peak near more than 240 wavenumbers associated with octahedral GeO6 groups grows relative to a peak near 500 wavenumbers associated with tetrahedral GeO4 groups. This change corresponds to an increase in octahedral germanium in the liquid from near 0 percent at ambient pressures to more than 50 percent at a pressure of 2.2 gigapascals. Silicate liquids pausibly undergo similar coordination changes at depth in the earth. Such structural changes may generate decreases in the fusion slopes of silicates at high pressures as well as neutrally buoyant magmas within the transition zone of the earth's mantle.

Farber, Danial L.↗