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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on BaNa2Ti2(Si2O7)2 by Materials Project

Na2BaTi2(Si2O7)2 crystallizes in the orthorhombic Ima2 space group. The structure is three-dimensional. there are two inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded in a 4-coordinate geometry to six O2- atoms. There are a spread of Na–O bond distances ranging from 2.34–2.72 Å. In the second Na1+ site, Na1+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Na–O bond distances ranging from 2.53–3.07 Å. Ba2+ is bonded to twelve O2- atoms to form distorted BaO12 cuboctahedra that share corners with four SiO4 tetrahedra, edges with four SiO4 tetrahedra, faces with two equivalent BaO12 cuboctahedra, and faces with two equivalent TiO6 octahedra. There are a spread of Ba–O bond distances ranging from 2.84–3.37 Å. There are two inequivalent Ti4+ sites. In the first Ti4+ site, Ti4+ is bonded to six O2- atoms to form distorted TiO6 octahedra that share corners with four equivalent SiO4 tetrahedra and faces with two equivalent BaO12 cuboctahedra. There are a spread of Ti–O bond distances ranging from 1.73–2.42 Å. In the second Ti4+ site, Ti4+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Ti–O bond distances ranging from 1.72–2.38 Å. There are two inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one BaO12 cuboctahedra, corners with two equivalent TiO6 octahedra, corners with two equivalent SiO4 tetrahedra, and an edgeedge with one BaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 27–45°. There are a spread of Si–O bond distances ranging from 1.62–1.66 Å. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one BaO12 cuboctahedra, corners with two equivalent SiO4 tetrahedra, and an edgeedge with one BaO12 cuboctahedra. There are a spread of Si–O bond distances ranging from 1.62–1.66 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to two Na1+, one Ti4+, and one Si4+ atom. In the second O2- site, O2- is bonded in a distorted single-bond geometry to one Ba2+ and two Ti4+ atoms. In the third O2- site, O2- is bonded in a 4-coordinate geometry to two Na1+, one Ti4+, and one Si4+ atom. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Na1+ and two Si4+ atoms. In the fifth O2- site, O2- is bonded in a distorted single-bond geometry to three Na1+, one Ba2+, and two Ti4+ atoms. In the sixth O2- site, O2- is bonded in a linear geometry to one Ba2+ and two Si4+ atoms. In the seventh O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Ba2+, one Ti4+, and one Si4+ atom. In the eighth O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Ba2+, one Ti4+, and one Si4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on BaNa4Ti2(Si2O5)6 by Materials Project

Na4BaTi2(Si2O5)6 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are two inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Na–O bond distances ranging from 2.25–2.94 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 2.23–2.64 Å. Ba2+ is bonded in a 10-coordinate geometry to ten O2- atoms. There are a spread of Ba–O bond distances ranging from 2.85–3.25 Å. Ti3+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with four SiO4 tetrahedra and an edgeedge with one TiO6 octahedra. There are a spread of Ti–O bond distances ranging from 1.94–2.17 Å. There are three inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one TiO6 octahedra and corners with three SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 46°. There are a spread of Si–O bond distances ranging from 1.58–1.70 Å. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share a cornercorner with one TiO6 octahedra and corners with three SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 41°. There are a spread of Si–O bond distances ranging from 1.59–1.70 Å. In the third Si4+ site, Si4+ is bonded to four O2- atoms to form corner-sharing SiO4 tetrahedra. There are a spread of Si–O bond distances ranging from 1.60–1.66 Å. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to one Na1+, one Ba2+, and two equivalent Ti3+ atoms. In the second O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+ and two equivalent Si4+ atoms. In the third O2- site, O2- is bonded in a linear geometry to two equivalent Si4+ atoms. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+, one Ti3+, and one Si4+ atom. In the fifth O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+ and two Si4+ atoms. In the sixth O2- site, O2- is bonded in a 4-coordinate geometry to one Na1+, one Ba2+, one Ti3+, and one Si4+ atom. In the seventh O2- site, O2- is bonded in a distorted bent 150 degrees geometry to one Na1+ and two Si4+ atoms. In the eighth O2- site, O2- is bonded in a bent 150 degrees geometry to one Ba2+ and two Si4+ atoms. In the ninth O2- site, O2- is bonded in a 2-coordinate geometry to two Na1+ and two Si4+ atoms.

36 MATERIALS SCIENCE↗