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DOE OSTI2020

Materials Data on NaHSeO4 by Materials Project

NaHSeO4 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share corners with two equivalent NaO6 octahedra, corners with six equivalent SeO4 tetrahedra, and an edgeedge with one NaO6 octahedra. The corner-sharing octahedral tilt angles are 67°. There are a spread of Na–O bond distances ranging from 2.39–2.49 Å. H1+ is bonded in a single-bond geometry to two O2- atoms. There is one shorter (1.02 Å) and one longer (1.74 Å) H–O bond length. Se6+ is bonded to four O2- atoms to form SeO4 tetrahedra that share corners with six equivalent NaO6 octahedra. The corner-sharing octahedra tilt angles range from 32–65°. There are a spread of Se–O bond distances ranging from 1.64–1.78 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Na1+ and one Se6+ atom. In the second O2- site, O2- is bonded in a trigonal planar geometry to two equivalent Na1+ and one Se6+ atom. In the third O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+, one H1+, and one Se6+ atom. In the fourth O2- site, O2- is bonded in a 1-coordinate geometry to one Na1+, one H1+, and one Se6+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NaH3(SeO3)2 by Materials Project

NaH3(SeO3)2 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Na1+ is bonded in a distorted octahedral geometry to six O2- atoms. There are a spread of Na–O bond distances ranging from 2.38–2.64 Å. There are two inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a linear geometry to two equivalent O2- atoms. Both H–O bond lengths are 1.22 Å. In the second H1+ site, H1+ is bonded in a distorted linear geometry to two O2- atoms. There is one shorter (1.03 Å) and one longer (1.60 Å) H–O bond length. Se4+ is bonded in a distorted trigonal non-coplanar geometry to three O2- atoms. There are a spread of Se–O bond distances ranging from 1.68–1.83 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+, one H1+, and one Se4+ atom. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to one Na1+, one H1+, and one Se4+ atom. In the third O2- site, O2- is bonded in a distorted single-bond geometry to one Na1+, one H1+, and one Se4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NaH2SeO4 by Materials Project

NaH2SeO4 crystallizes in the orthorhombic Cmc2_1 space group. The structure is three-dimensional. Na is bonded to six O atoms to form NaO6 octahedra that share corners with three equivalent SeO4 tetrahedra and edges with two equivalent NaO6 octahedra. There are a spread of Na–O bond distances ranging from 2.40–2.51 Å. There are three inequivalent H sites. In the first H site, H is bonded in a distorted single-bond geometry to two O atoms. There is one shorter (1.02 Å) and one longer (1.65 Å) H–O bond length. In the second H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. In the third H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.97 Å. There are two inequivalent Se sites. In the first Se site, Se is bonded in a trigonal non-coplanar geometry to three O atoms. There is one shorter (1.67 Å) and two longer (1.81 Å) Se–O bond length. In the second Se site, Se is bonded to four O atoms to form SeO4 tetrahedra that share corners with six equivalent NaO6 octahedra. The corner-sharing octahedra tilt angles range from 49–52°. There are a spread of Se–O bond distances ranging from 1.66–1.69 Å. There are six inequivalent O sites. In the first O site, O is bonded in a distorted trigonal planar geometry to two equivalent Na and one Se atom. In the second O site, O is bonded in a distorted T-shaped geometry to two equivalent Na and one Se atom. In the third O site, O is bonded in a 3-coordinate geometry to one Na, one H, and one Se atom. In the fourth O site, O is bonded in a distorted single-bond geometry to one Na, one H, and one Se atom. In the fifth O site, O is bonded in a distorted trigonal planar geometry to two equivalent Na and one Se atom. In the sixth O site, O is bonded in a distorted water-like geometry to two equivalent Na and two H atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na5H7(Se2O9)2 by Materials Project

Na5H7(Se2O9)2 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are three inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share corners with four equivalent SeO4 tetrahedra and edges with two equivalent NaO6 octahedra. There are a spread of Na–O bond distances ranging from 2.38–2.87 Å. In the second Na1+ site, Na1+ is bonded to six O2- atoms to form NaO6 octahedra that share corners with six SeO4 tetrahedra and edges with two NaO6 octahedra. There are a spread of Na–O bond distances ranging from 2.42–2.54 Å. In the third 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 2.34–2.83 Å. There are four inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a linear geometry to two equivalent O2- atoms. Both H–O bond lengths are 1.22 Å. In the second H1+ site, H1+ is bonded in a distorted linear geometry to two O2- atoms. There is one shorter (1.02 Å) and one longer (1.60 Å) H–O bond length. In the third H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the fourth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. There are two inequivalent Se6+ sites. In the first Se6+ site, Se6+ is bonded to four O2- atoms to form SeO4 tetrahedra that share corners with four equivalent NaO6 octahedra. The corner-sharing octahedra tilt angles range from 41–59°. There are a spread of Se–O bond distances ranging from 1.66–1.73 Å. In the second Se6+ site, Se6+ is bonded to four O2- atoms to form SeO4 tetrahedra that share corners with four NaO6 octahedra. The corner-sharing octahedra tilt angles range from 42–74°. There are a spread of Se–O bond distances ranging from 1.64–1.78 Å. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted water-like geometry to two Na1+ and two H1+ atoms. In the second O2- site, O2- is bonded in a 1-coordinate geometry to two Na1+, one H1+, and one Se6+ atom. In the third O2- site, O2- is bonded in a 4-coordinate geometry to three Na1+ and one Se6+ atom. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+, one H1+, and one Se6+ atom. In the fifth O2- site, O2- is bonded in a 2-coordinate geometry to one Na1+ and one Se6+ atom. In the sixth O2- site, O2- is bonded in a 1-coordinate geometry to one Na1+, one H1+, and one Se6+ atom. In the seventh O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to three Na1+ and one Se6+ atom. In the eighth O2- site, O2- is bonded in a bent 150 degrees geometry to one Na1+ and one Se6+ atom. In the ninth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Na1+ and one Se6+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NaHSeO3 by Materials Project

NaHSeO3 crystallizes in the monoclinic C2/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 a mixture of edge and corner-sharing NaO6 octahedra. There are a spread of Na–O bond distances ranging from 2.41–2.51 Å. In the second Na1+ site, Na1+ is bonded to five O2- atoms to form distorted NaO5 trigonal bipyramids that share corners with three equivalent NaO6 octahedra, corners with two equivalent NaO5 trigonal bipyramids, and an edgeedge with one NaO6 octahedra. The corner-sharing octahedra tilt angles range from 62–80°. There are a spread of Na–O bond distances ranging from 2.35–2.69 Å. There are two inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.03 Å) and one longer (1.60 Å) H–O bond length. In the second H1+ site, H1+ is bonded in a distorted single-bond geometry to two O2- atoms. There is one shorter (1.02 Å) and one longer (1.70 Å) H–O bond length. There are two inequivalent Se4+ sites. In the first Se4+ site, Se4+ is bonded in a trigonal non-coplanar geometry to three O2- atoms. There are a spread of Se–O bond distances ranging from 1.69–1.86 Å. In the second Se4+ site, Se4+ is bonded in a trigonal non-coplanar geometry to three O2- atoms. There are a spread of Se–O bond distances ranging from 1.70–1.84 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to two Na1+ and one Se4+ atom. In the second O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+, one H1+, and one Se4+ atom. In the third O2- site, O2- is bonded in a 4-coordinate geometry to two Na1+, one H1+, and one Se4+ atom. In the fourth O2- site, O2- is bonded in a distorted single-bond geometry to one Na1+, one H1+, and one Se4+ atom. In the fifth O2- site, O2- is bonded to three Na1+ and one Se4+ atom to form distorted corner-sharing ONa3Se tetrahedra. In the sixth O2- site, O2- is bonded in a distorted single-bond geometry to two Na1+, one H1+, and one Se4+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na5H7(Se2O9)2 by Materials Project

Na5H7(Se2O9)2 crystallizes in the monoclinic Cc space group. The structure is three-dimensional. there are five inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share corners with six SeO4 tetrahedra and edges with two NaO6 octahedra. There are a spread of Na–O bond distances ranging from 2.43–2.51 Å. In the second Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share corners with six SeO4 tetrahedra and edges with two NaO6 octahedra. There are a spread of Na–O bond distances ranging from 2.43–2.59 Å. In the third Na1+ site, Na1+ is bonded to six O2- atoms to form NaO6 octahedra that share corners with two NaO6 octahedra, corners with two SeO4 tetrahedra, and edges with two equivalent NaO6 octahedra. The corner-sharing octahedra tilt angles range from 68–70°. There are a spread of Na–O bond distances ranging from 2.36–2.62 Å. In the fourth Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share a cornercorner with one NaO6 octahedra, corners with six SeO4 tetrahedra, and edges with two NaO6 octahedra. The corner-sharing octahedral tilt angles are 68°. There are a spread of Na–O bond distances ranging from 2.34–2.62 Å. In the fifth Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share a cornercorner with one NaO6 octahedra, corners with six SeO4 tetrahedra, and edges with two NaO6 octahedra. The corner-sharing octahedral tilt angles are 70°. There are a spread of Na–O bond distances ranging from 2.34–2.63 Å. There are seven inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the second H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.99 Å. In the third H1+ site, H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.06 Å) and one longer (1.45 Å) H–O bond length. In the fourth H1+ site, H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.03 Å) and one longer (1.55 Å) H–O bond length. In the fifth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the sixth H1+ site, H1+ is bonded in a single-bond geometry to one O2- atom. The H–O bond length is 0.98 Å. In the seventh H1+ site, H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.07 Å) and one longer (1.43 Å) H–O bond length. There are four inequivalent Se6+ sites. In the first Se6+ site, Se6+ is bonded to four O2- atoms to form SeO4 tetrahedra that share corners with seven NaO6 octahedra. The corner-sharing octahedra tilt angles range from 38–61°. There are a spread of Se–O bond distances ranging from 1.65–1.76 Å. In the second Se6+ site, Se6+ is bonded to four O2- atoms to form SeO4 tetrahedra that share corners with seven NaO6 octahedra. The corner-sharing octahedra tilt angles range from 37–61°. There are a spread of Se–O bond distances ranging from 1.65–1.77 Å. In the third Se6+ site, Se6+ is bonded to four O2- atoms to form SeO4 tetrahedra that share corners with six NaO6 octahedra. The corner-sharing octahedra tilt angles range from 43–69°. There are a spread of Se–O bond distances ranging from 1.65–1.75 Å. In the fourth Se6+ site, Se6+ is bonded to four O2- atoms to form SeO4 tetrahedra that share corners with six NaO6 octahedra. The corner-sharing octahedra tilt angles range from 47–69°. There are a spread of Se–O bond distances ranging from 1.66–1.69 Å. There are eighteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to one Na1+, one H1+, and one Se6+ atom. In the second O2- site, O2- is bonded in a 1-coordinate geometry to one Na1+, one H1+, and one Se6+ atom. In the third O2- site, O2- is bonded in a 3-coordinate geometry to two Na1+ and one Se6+ atom. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to two Na1+ and one Se6+ atom. In the fifth O2- site, O2- is bonded in a 3-coordinate geometry to two Na1+ and one Se6+ atom. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to two Na1+ and one Se6+ atom. In the seventh O2- site, O2- is bonded in a 1-coordinate geometry to one Na1+, one H1+, and one Se6+ atom. In the eighth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Na1+, one H1+, and one Se6+ atom. In the ninth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Na1+ and one Se6+ atom. In the tenth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Na1+ and one Se6+ atom. In the eleventh O2- site, O2- is bonded in a distorted trigonal planar geometry to two Na1+ and one Se6+ atom. In the twelfth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Na1+ and one Se6+ atom. In the thirteenth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two Na1+ and one Se6+ atom. In the fourteenth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to two Na1+ and one Se6+ atom. In the fifteenth O2- site, O2- is bonded in a distorted water-like geometry to two equivalent Na1+ and two H1+ atoms. In the sixteenth O2- site, O2- is bonded in a distorted water-like geometry to two equivalent Na1+ and two H1+ atoms. In the seventeenth O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+, one H1+, and one Se6+ atom. In the eighteenth O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+, one H1+, and one Se6+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na5H7(Se2O9)2 by Materials Project

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na3H5(SeO4)4 by Materials Project

Na3H5(SeO4)4 crystallizes in the triclinic P-1 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 NaO6 octahedra that share a cornercorner with one NaO6 octahedra, corners with six SeO4 tetrahedra, and edges with two equivalent NaO6 octahedra. The corner-sharing octahedral tilt angles are 71°. There are a spread of Na–O bond distances ranging from 2.43–2.51 Å. In the second Na1+ site, Na1+ is bonded to six O2- atoms to form NaO6 octahedra that share corners with two equivalent NaO6 octahedra and corners with six SeO4 tetrahedra. The corner-sharing octahedral tilt angles are 71°. There are four shorter (2.44 Å) and two longer (2.58 Å) Na–O bond lengths. There are three inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to two O2- atoms. There is one shorter (1.01 Å) and one longer (1.72 Å) H–O bond length. In the second H1+ site, H1+ is bonded in a linear geometry to two equivalent O2- atoms. Both H–O bond lengths are 1.21 Å. In the third H1+ site, H1+ is bonded in a distorted linear geometry to two O2- atoms. There is one shorter (1.02 Å) and one longer (1.62 Å) H–O bond length. There are two inequivalent Se6+ sites. In the first Se6+ site, Se6+ is bonded to four O2- atoms to form SeO4 tetrahedra that share corners with four NaO6 octahedra. The corner-sharing octahedra tilt angles range from 41–52°. There are a spread of Se–O bond distances ranging from 1.65–1.76 Å. In the second Se6+ site, Se6+ is bonded to four O2- atoms to form SeO4 tetrahedra that share corners with five NaO6 octahedra. The corner-sharing octahedra tilt angles range from 33–56°. There are a spread of Se–O bond distances ranging from 1.64–1.74 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to one Na1+, one H1+, and one Se6+ atom. In the second O2- site, O2- is bonded in a 3-coordinate geometry to two equivalent Na1+ and one Se6+ atom. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to one Na1+, one H1+, and one Se6+ atom. In the fourth O2- site, O2- is bonded in a distorted water-like geometry to one H1+ and one Se6+ atom. In the fifth O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Na1+ and one Se6+ atom. In the sixth O2- site, O2- is bonded in a trigonal planar geometry to two Na1+ and one Se6+ atom. In the seventh O2- site, O2- is bonded in a 1-coordinate geometry to one Na1+, one H1+, and one Se6+ atom. In the eighth O2- site, O2- is bonded in a distorted water-like geometry to one H1+ and one Se6+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NaHSeO4 by Materials Project

NaHSeO4 crystallizes in the triclinic P1 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 NaO6 octahedra that share corners with six SeO4 tetrahedra and edges with two equivalent NaO6 octahedra. There are a spread of Na–O bond distances ranging from 2.35–2.51 Å. In the second Na1+ site, Na1+ is bonded to six O2- atoms to form NaO6 octahedra that share corners with six SeO4 tetrahedra and edges with two equivalent NaO6 octahedra. There are a spread of Na–O bond distances ranging from 2.37–2.55 Å. There are two inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.03 Å) and one longer (1.57 Å) H–O bond length. In the second H1+ site, H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.04 Å) and one longer (1.52 Å) H–O bond length. There are two inequivalent Se6+ sites. In the first Se6+ site, Se6+ is bonded to four O2- atoms to form SeO4 tetrahedra that share corners with six NaO6 octahedra. The corner-sharing octahedra tilt angles range from 45–55°. There are a spread of Se–O bond distances ranging from 1.64–1.77 Å. In the second Se6+ site, Se6+ is bonded to four O2- atoms to form SeO4 tetrahedra that share corners with six NaO6 octahedra. The corner-sharing octahedra tilt angles range from 43–56°. There are a spread of Se–O bond distances ranging from 1.64–1.76 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to two Na1+ and one Se6+ atom. In the second O2- site, O2- is bonded in a 3-coordinate geometry to two Na1+ and one Se6+ atom. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to two Na1+ and one Se6+ atom. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Na1+ and one Se6+ atom. In the fifth O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+, one H1+, and one Se6+ atom. In the sixth O2- site, O2- is bonded in a 1-coordinate geometry to one Na1+, one H1+, and one Se6+ atom. In the seventh O2- site, O2- is bonded in a distorted trigonal planar geometry to one Na1+, one H1+, and one Se6+ atom. In the eighth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Na1+, one H1+, and one Se6+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na3H5(SeO4)4 by Materials Project

Na3H5(SeO4)4 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are three inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded to six O2- atoms to form NaO6 octahedra that share a cornercorner with one NaO6 octahedra, corners with six SeO4 tetrahedra, and edges with two equivalent NaO6 octahedra. The corner-sharing octahedral tilt angles are 74°. There are a spread of Na–O bond distances ranging from 2.41–2.48 Å. In the second Na1+ site, Na1+ is bonded to six O2- atoms to form NaO6 octahedra that share a cornercorner with one NaO6 octahedra, corners with six SeO4 tetrahedra, and edges with two equivalent NaO6 octahedra. The corner-sharing octahedral tilt angles are 68°. There are a spread of Na–O bond distances ranging from 2.40–2.54 Å. In the third Na1+ site, Na1+ is bonded to six O2- atoms to form NaO6 octahedra that share corners with two NaO6 octahedra and corners with six SeO4 tetrahedra. The corner-sharing octahedra tilt angles range from 68–74°. There are a spread of Na–O bond distances ranging from 2.42–2.64 Å. There are five inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a single-bond geometry to two O2- atoms. There is one shorter (1.01 Å) and one longer (1.71 Å) H–O bond length. In the second H1+ site, H1+ is bonded in a distorted single-bond geometry to two O2- atoms. There is one shorter (1.01 Å) and one longer (1.68 Å) H–O bond length. In the third H1+ site, H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.04 Å) and one longer (1.55 Å) H–O bond length. In the fourth H1+ site, H1+ is bonded in a distorted linear geometry to two O2- atoms. There is one shorter (1.02 Å) and one longer (1.63 Å) H–O bond length. In the fifth H1+ site, H1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.08 Å) and one longer (1.44 Å) H–O bond length. There are four inequivalent Se6+ sites. In the first Se6+ site, Se6+ is bonded to four O2- atoms to form SeO4 tetrahedra that share corners with five NaO6 octahedra. The corner-sharing octahedra tilt angles range from 28–58°. There is two shorter (1.64 Å) and two longer (1.73 Å) Se–O bond length. In the second Se6+ site, Se6+ is bonded to four O2- atoms to form SeO4 tetrahedra that share corners with five NaO6 octahedra. The corner-sharing octahedra tilt angles range from 36–54°. There are a spread of Se–O bond distances ranging from 1.65–1.75 Å. In the third Se6+ site, Se6+ is bonded to four O2- atoms to form SeO4 tetrahedra that share corners with four NaO6 octahedra. The corner-sharing octahedra tilt angles range from 42–55°. There are a spread of Se–O bond distances ranging from 1.65–1.76 Å. In the fourth Se6+ site, Se6+ is bonded to four O2- atoms to form SeO4 tetrahedra that share corners with four NaO6 octahedra. The corner-sharing octahedra tilt angles range from 39–53°. There are a spread of Se–O bond distances ranging from 1.65–1.75 Å. There are sixteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to two Na1+ and one Se6+ atom. In the second O2- site, O2- is bonded in a 3-coordinate geometry to two Na1+ and one Se6+ atom. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to one Na1+, one H1+, and one Se6+ atom. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+, one H1+, and one Se6+ atom. In the fifth O2- site, O2- is bonded in a distorted water-like geometry to one H1+ and one Se6+ atom. In the sixth O2- site, O2- is bonded in a distorted water-like geometry to one H1+ and one Se6+ atom. In the seventh O2- site, O2- is bonded in a 1-coordinate geometry to one Na1+, one H1+, and one Se6+ atom. In the eighth O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+, one H1+, and one Se6+ atom. In the ninth O2- site, O2- is bonded in a trigonal planar geometry to one Na1+, one H1+, and one Se6+ atom. In the tenth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Na1+, one H1+, and one Se6+ atom. In the eleventh O2- site, O2- is bonded in a distorted trigonal planar geometry to two Na1+ and one Se6+ atom. In the twelfth O2- site, O2- is bonded in a distorted trigonal planar geometry to two Na1+ and one Se6+ atom. In the thirteenth O2- site, O2- is bonded in a distorted water-like geometry to one H1+ and one Se6+ atom. In the fourteenth O2- site, O2- is bonded in a distorted water-like geometry to one H1+ and one Se6+ atom. In the fifteenth O2- site, O2- is bonded in a trigonal planar geometry to two Na1+ and one Se6+ atom. In the sixteenth O2- site, O2- is bonded in a trigonal planar geometry to two Na1+ and one Se6+ atom.

36 MATERIALS SCIENCE↗