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Materials Data on NaCa4TaTi4(SiO5)5 by Materials Project

NaCa4Ti4Ta(SiO5)5 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 in a 7-coordinate geometry to seven O2- atoms. There are a spread of Na–O bond distances ranging from 2.31–2.87 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 2.30–2.84 Å. There are eight inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Ca–O bond distances ranging from 2.29–2.67 Å. In the second Ca2+ site, Ca2+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Ca–O bond distances ranging from 2.29–2.70 Å. In the third Ca2+ site, Ca2+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Ca–O bond distances ranging from 2.27–2.71 Å. In the fourth Ca2+ site, Ca2+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Ca–O bond distances ranging from 2.29–2.67 Å. In the fifth Ca2+ site, Ca2+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Ca–O bond distances ranging from 2.28–2.76 Å. In the sixth Ca2+ site, Ca2+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Ca–O bond distances ranging from 2.30–2.72 Å. In the seventh Ca2+ site, Ca2+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Ca–O bond distances ranging from 2.29–2.68 Å. In the eighth Ca2+ site, Ca2+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Ca–O bond distances ranging from 2.29–2.66 Å. There are eight inequivalent Ti4+ sites. In the first Ti4+ site, Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with two TiO6 octahedra and corners with four SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 38°. There are a spread of Ti–O bond distances ranging from 1.83–2.04 Å. In the second Ti4+ site, Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share a cornercorner with one TiO6 octahedra, a cornercorner with one TaO6 octahedra, and corners with four SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 38–39°. There are a spread of Ti–O bond distances ranging from 1.83–2.05 Å. In the third Ti4+ site, Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with two TaO6 octahedra and corners with four SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 38–39°. There are a spread of Ti–O bond distances ranging from 1.88–2.03 Å. In the fourth Ti4+ site, Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share a cornercorner with one TiO6 octahedra, a cornercorner with one TaO6 octahedra, and corners with four SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 38°. There are a spread of Ti–O bond distances ranging from 1.88–2.03 Å. In the fifth Ti4+ site, Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with two TiO6 octahedra and corners with four SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 37–38°. There are a spread of Ti–O bond distances ranging from 1.86–2.04 Å. In the sixth Ti4+ site, Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with two TiO6 octahedra and corners with four SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 37°. There are a spread of Ti–O bond distances ranging from 1.83–2.04 Å. In the seventh Ti4+ site, Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with two TiO6 octahedra and corners with four SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 37°. There are a spread of Ti–O bond distances ranging from 1.83–2.04 Å. In the eighth Ti4+ site, Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with two TiO6 octahedra and corners with four SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 37–38°. There are a spread of Ti–O bond distances ranging from 1.82–2.04 Å. There are two inequivalent Ta5+ sites. In the first Ta5+ site, Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with two TiO6 octahedra and corners with four SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 38–39°. There are a spread of Ta–O bond distances ranging from 1.90–2.06 Å. In the second Ta5+ site, Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with two TiO6 octahedra and corners with four SiO4 tetrahedra. The corner-sharing octahedra tilt angles range from 38–39°. There are a spread of Ta–O bond distances ranging from 1.89–2.05 Å. There are ten inequivalent Si4+ sites. In the first Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with two equivalent TiO6 octahedra and corners with two equivalent TaO6 octahedra. The corner-sharing octahedra tilt angles range from 37–53°. There are a spread of Si–O bond distances ranging from 1.64–1.66 Å. In the second Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with two equivalent TiO6 octahedra and corners with two equivalent TaO6 octahedra. The corner-sharing octahedra tilt angles range from 37–53°. There is two shorter (1.64 Å) and two longer (1.66 Å) Si–O bond length. In the third Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with four TiO6 octahedra. The corner-sharing octahedra tilt angles range from 38–53°. There is two shorter (1.65 Å) and two longer (1.66 Å) Si–O bond length. In the fourth Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with four TiO6 octahedra. The corner-sharing octahedra tilt angles range from 37–53°. There is two shorter (1.65 Å) and two longer (1.66 Å) Si–O bond length. In the fifth Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with four TiO6 octahedra. The corner-sharing octahedra tilt angles range from 36–53°. There is two shorter (1.65 Å) and two longer (1.66 Å) Si–O bond length. In the sixth Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with two equivalent TiO6 octahedra and corners with two equivalent TaO6 octahedra. The corner-sharing octahedra tilt angles range from 36–51°. There is two shorter (1.64 Å) and two longer (1.66 Å) Si–O bond length. In the seventh Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with four TiO6 octahedra. The corner-sharing octahedra tilt angles range from 36–53°. There is three shorter (1.65 Å) and one longer (1.66 Å) Si–O bond length. In the eighth Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with two equivalent TiO6 octahedra and corners with two equivalent TaO6 octahedra. The corner-sharing octahedra tilt angles range from 36–50°. There is two shorter (1.64 Å) and two longer (1.66 Å) Si–O bond length. In the ninth Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with four TiO6 octahedra. The corner-sharing octahedra tilt angles range from 37–53°. There is two shorter (1.65 Å) and two longer (1.66 Å) Si–O bond length. In the tenth Si4+ site, Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with four TiO6 octahedra. The corner-sharing octahedra tilt angles range from 36–54°. There is three shorter (1.65 Å) and one longer (1.66 Å) Si–O bond length. There are fifty inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, one Ti4+, and one Si4+ atom. In the second O2- site, O2- is bonded in a 4-coordinate geometry to two Ca2+, one Ti4+, and one Si4+ atom. In the third O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+, one Ta5+, and one Si4+ atom. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+ and two Ti4+ atoms. In the fifth O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, one Ti4+, and one Si4+ atom. In the sixth O2- site, O2- is bonded in a 4-coordinate geometry to one Na1+, one Ca2+, one Ta5+, and one Si4+ atom. In the seventh O2- site, O2- is bonded in a 4-coordinate geometry to one Na1+, one Ca2+, one Ti4+, and one Si4+ atom. In the eighth O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+, one Ta5+, and one Si4+ atom. In the ninth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Na1+, one Ti4+, and one Ta5+ atom. In the tenth O2- site, O2- is bonded in a 4-coordinate geometry to two Ca2+, one Ti4+, and one Si4+ atom. In the eleventh O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, one Ti4+, and one Si4+ atom. In the twelfth O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, one Ti4+, and one Si4+ atom. In the thirteenth O2- site, O2- is bonded in a 4-coordinate geometry to one Na1+, one Ca2+, one Ta5+, and one Si4+ atom. In the fourteenth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ca2+, one Ti4+, and one Ta5+ atom. In the fifteenth O2- site, O2- is bonded in a 4-coordinate geometry to one Na1+, one Ca2+, one Ti4+, and one Si4+ atom. In the sixteenth O2- site, O2- is bonded in a 4-coordinate geometry to two Ca2+, one Ti4+, and one Si4+ atom. In the seventeenth O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, one Ti4+, and one Si4+ atom. In the eighteenth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Na1+, one Ti4+, and one Ta5+ atom. In the nineteenth O2- site, O2- is bonded in a 4-coordinate geometry to one Na1+, one Ca2+, one Ta5+, and one Si4+ atom. In the twentieth O2- site, O2- is bonded in a distorted T-shaped geometry to one Na1+, one Ti4+, and one Si4+ atom. In the twenty-first O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, one Ti4+, and one Si4+ atom. In the twenty-second O2- site, O2- is bonded in a 4-coordinate geometry to two Ca2+, one Ti4+, and one Si4+ atom. In the twenty-third O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ca2+, one Ti4+, and one Ta5+ atom. In the twenty-fourth O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, one Ta5+, and one Si4+ atom. In the twenty-fifth O2- site, O2- is bonded in a 4-coordinate geometry to two Ca2+, one Ti4+, and one Si4+ atom. In the twenty-sixth O2- site, O2- is bonded in a 4-coordinate geometry to one Na1+, one Ca2+, one Ti4+, and one Si4+ atom. In the twenty-seventh O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, one Ti4+, and one Si4+ atom. In the twenty-eighth O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+ and two Ti4+ atoms. In the twenty-ninth O2- site, O2- is bonded in a 4-coordinate geometry to one Na1+, one Ca2+, one Ta5+, and one Si4+ atom. In the thirtieth O2- site, O2- is bonded in a distorted T-shaped geometry to one Na1+, one Ti4+, and one Si4+ atom. In the thirty-first O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, one Ti4+, and one Si4+ atom. In the thirty-second O2- site, O2- is bonded in a 4-coordinate geometry to two Ca2+, one Ti4+, and one Si4+ atom. In the thirty-third O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ca2+ and two Ti4+ atoms. In the thirty-fourth O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+, one Ta5+, and one Si4+ atom. In the thirty-fifth O2- site, O2- is bonded in a 4-coordinate geometry to two Ca2+, one Ti4+, and one Si4+ atom. In the thirty-sixth O2- site, O2- is bonded in a 4-coordinate geometry to one Na1+, one Ca2+, one Ti4+, and one Si4+ atom. In the thirty-seventh O2- site, O2- is bonded in a 3-coordinate geometry to one Ca2+ and two Ti4+ atoms. In the thirty-eighth O2- site, O2- is bonded in a 4-coordinate geometry to two Ca2+, one Ti4+, and one Si4+ atom. In the thirty-ni

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on YTa3O9 by Materials Project

YTa3O9 crystallizes in the monoclinic P2_1/m space group. The structure is three-dimensional. Y3+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Y–O bond distances ranging from 2.32–2.50 Å. There are two inequivalent Ta5+ sites. In the first Ta5+ site, Ta5+ is bonded to six O2- atoms to form corner-sharing TaO6 octahedra. The corner-sharing octahedra tilt angles range from 31–50°. There are a spread of Ta–O bond distances ranging from 1.96–2.05 Å. In the second Ta5+ site, Ta5+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing TaO6 octahedra. The corner-sharing octahedra tilt angles range from 33–50°. There are a spread of Ta–O bond distances ranging from 1.86–2.19 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent Ta5+ atoms. In the second O2- site, O2- is bonded in a 3-coordinate geometry to one Y3+ and two Ta5+ atoms. In the third O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Y3+ and two equivalent Ta5+ atoms. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to one Y3+ and two equivalent Ta5+ atoms. In the fifth O2- site, O2- is bonded in a bent 150 degrees geometry to two Ta5+ atoms. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to one Y3+ and two equivalent Ta5+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ta2CuO6 by Materials Project

CuTa2O6 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are two inequivalent Ta5+ sites. In the first Ta5+ site, Ta5+ is bonded to six O2- atoms to form corner-sharing TaO6 octahedra. The corner-sharing octahedra tilt angles range from 29–39°. There are a spread of Ta–O bond distances ranging from 1.94–2.08 Å. In the second Ta5+ site, Ta5+ is bonded to six O2- atoms to form corner-sharing TaO6 octahedra. The corner-sharing octahedra tilt angles range from 29–39°. There are a spread of Ta–O bond distances ranging from 1.93–2.08 Å. Cu2+ is bonded in a distorted trigonal planar geometry to three O2- atoms. There is two shorter (1.93 Å) and one longer (1.97 Å) Cu–O bond length. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to two Ta5+ and one Cu2+ atom. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to two Ta5+ and one Cu2+ atom. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to two Ta5+ and one Cu2+ atom. In the fourth O2- site, O2- is bonded in a bent 150 degrees geometry to two Ta5+ atoms. In the fifth O2- site, O2- is bonded in a bent 150 degrees geometry to two Ta5+ atoms. In the sixth O2- site, O2- is bonded in a bent 150 degrees geometry to two Ta5+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LiTaO3 by Materials Project

LiTaO3 crystallizes in the tetragonal P4/mbm space group. The structure is three-dimensional. there are two inequivalent Li1+ sites. In the first Li1+ site, Li1+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are four shorter (2.43 Å) and four longer (2.72 Å) Li–O bond lengths. In the second Li1+ site, Li1+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are four shorter (2.43 Å) and four longer (2.72 Å) Li–O bond lengths. There are two inequivalent Ta5+ sites. In the first Ta5+ site, Ta5+ is bonded to six O2- atoms to form corner-sharing TaO6 octahedra. The corner-sharing octahedra tilt angles range from 0–30°. There is two shorter (1.97 Å) and four longer (1.99 Å) Ta–O bond length. In the second Ta5+ site, Ta5+ is bonded to six O2- atoms to form corner-sharing TaO6 octahedra. The corner-sharing octahedra tilt angles range from 0–30°. There is two shorter (1.97 Å) and four longer (1.99 Å) Ta–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted linear geometry to four Li1+ and two equivalent Ta5+ atoms. In the second O2- site, O2- is bonded to two equivalent Li1+ and two Ta5+ atoms to form a mixture of distorted edge and corner-sharing OLi2Ta2 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ta2Pb2O7 by Materials Project

Pb2Ta2O7 crystallizes in the orthorhombic Cmc2_1 space group. The structure is three-dimensional. there are two inequivalent Ta5+ sites. In the first Ta5+ site, Ta5+ is bonded to six O2- atoms to form corner-sharing TaO6 octahedra. The corner-sharing octahedra tilt angles range from 2–19°. There are a spread of Ta–O bond distances ranging from 1.88–2.23 Å. In the second Ta5+ site, Ta5+ is bonded to six O2- atoms to form distorted corner-sharing TaO6 octahedra. The corner-sharing octahedra tilt angles range from 2–19°. There are a spread of Ta–O bond distances ranging from 1.85–2.35 Å. There are two inequivalent Pb2+ sites. In the first Pb2+ site, Pb2+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Pb–O bond distances ranging from 2.49–2.59 Å. In the second Pb2+ site, Pb2+ is bonded in a 11-coordinate geometry to eleven O2- atoms. There are a spread of Pb–O bond distances ranging from 2.55–3.09 Å. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to two Ta5+ and two equivalent Pb2+ atoms. In the second O2- site, O2- is bonded in a 1-coordinate geometry to two equivalent Ta5+ and four equivalent Pb2+ atoms. In the third O2- site, O2- is bonded in a distorted single-bond geometry to one Ta5+ and three equivalent Pb2+ atoms. In the fourth O2- site, O2- is bonded in a distorted linear geometry to two Ta5+ and two equivalent Pb2+ atoms. In the fifth O2- site, O2- is bonded in a distorted single-bond geometry to one Ta5+ and three equivalent Pb2+ atoms. In the sixth O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Ta5+ and one Pb2+ atom. In the seventh O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Ta5+ and two equivalent Pb2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on TaCuO3 by Materials Project

CuTaO3 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are two inequivalent Ta5+ sites. In the first Ta5+ site, Ta5+ is bonded to six O2- atoms to form a mixture of distorted edge and corner-sharing TaO6 octahedra. The corner-sharing octahedral tilt angles are 6°. There are a spread of Ta–O bond distances ranging from 1.83–2.29 Å. In the second Ta5+ site, Ta5+ is bonded to six O2- atoms to form a mixture of distorted edge and corner-sharing TaO6 octahedra. The corner-sharing octahedral tilt angles are 6°. There are a spread of Ta–O bond distances ranging from 1.89–2.16 Å. There are two inequivalent Cu1+ sites. In the first Cu1+ site, Cu1+ is bonded in a linear geometry to two O2- atoms. There is one shorter (1.81 Å) and one longer (1.85 Å) Cu–O bond length. In the second Cu1+ site, Cu1+ is bonded in a linear geometry to two equivalent O2- atoms. Both Cu–O bond lengths are 1.89 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded to three Ta5+ and one Cu1+ atom to form distorted edge-sharing OTa3Cu tetrahedra. In the second O2- site, O2- is bonded in a bent 120 degrees geometry to one Ta5+ and one Cu1+ atom. In the third O2- site, O2- is bonded in a linear geometry to two Ta5+ atoms. In the fourth O2- site, O2- is bonded in a trigonal non-coplanar geometry to two Ta5+ and one Cu1+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Er3TaO7 by Materials Project

Er3TaO7 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are three inequivalent Er3+ sites. In the first Er3+ site, Er3+ is bonded to seven O2- atoms to form distorted ErO7 pentagonal bipyramids that share corners with two TaO6 octahedra, a cornercorner with one ErO7 pentagonal bipyramid, an edgeedge with one TaO6 octahedra, and edges with four ErO7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 44–50°. There are a spread of Er–O bond distances ranging from 2.29–2.45 Å. In the second Er3+ site, Er3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Er–O bond distances ranging from 2.20–2.81 Å. In the third Er3+ site, Er3+ is bonded to seven O2- atoms to form distorted ErO7 pentagonal bipyramids that share corners with two TaO6 octahedra, a cornercorner with one ErO7 pentagonal bipyramid, edges with two TaO6 octahedra, and edges with four ErO7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 43–45°. There are a spread of Er–O bond distances ranging from 2.18–2.41 Å. There are two inequivalent Ta5+ sites. In the first Ta5+ site, Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with two equivalent TaO6 octahedra, corners with four ErO7 pentagonal bipyramids, and edges with four ErO7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 39°. There are four shorter (1.99 Å) and two longer (2.01 Å) Ta–O bond lengths. In the second Ta5+ site, Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with two equivalent TaO6 octahedra, corners with four ErO7 pentagonal bipyramids, and edges with two equivalent ErO7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 39°. There are a spread of Ta–O bond distances ranging from 1.98–2.06 Å. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to three Er3+ and one Ta5+ atom. In the second O2- site, O2- is bonded in a 4-coordinate geometry to three Er3+ and one Ta5+ atom. In the third O2- site, O2- is bonded in a 4-coordinate geometry to three Er3+ and one Ta5+ atom. In the fourth O2- site, O2- is bonded in a 4-coordinate geometry to three Er3+ and one Ta5+ atom. In the fifth O2- site, O2- is bonded in a 3-coordinate geometry to one Er3+ and two Ta5+ atoms. In the sixth O2- site, O2- is bonded to four Er3+ atoms to form a mixture of edge and corner-sharing OEr4 tetrahedra. In the seventh O2- site, O2- is bonded to four Er3+ atoms to form a mixture of edge and corner-sharing OEr4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on ErTa3O9 by Materials Project

ErTa3O9 crystallizes in the monoclinic P2_1/m space group. The structure is three-dimensional. Er3+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Er–O bond distances ranging from 2.29–2.50 Å. There are two inequivalent Ta5+ sites. In the first Ta5+ site, Ta5+ is bonded to six O2- atoms to form corner-sharing TaO6 octahedra. The corner-sharing octahedra tilt angles range from 32–51°. There are a spread of Ta–O bond distances ranging from 1.96–2.05 Å. In the second Ta5+ site, Ta5+ is bonded to six O2- atoms to form a mixture of corner and edge-sharing TaO6 octahedra. The corner-sharing octahedra tilt angles range from 34–51°. There are a spread of Ta–O bond distances ranging from 1.86–2.19 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent Ta5+ atoms. In the second O2- site, O2- is bonded in a 3-coordinate geometry to one Er3+ and two Ta5+ atoms. In the third O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Er3+ and two equivalent Ta5+ atoms. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Er3+ and two equivalent Ta5+ atoms. In the fifth O2- site, O2- is bonded in a bent 150 degrees geometry to two Ta5+ atoms. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to one Er3+ and two equivalent Ta5+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LuTa3O9 by Materials Project

LuTa3O9 crystallizes in the monoclinic P2_1/m space group. The structure is three-dimensional. Lu3+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Lu–O bond distances ranging from 2.24–2.49 Å. There are two inequivalent Ta5+ sites. In the first Ta5+ site, Ta5+ is bonded to six O2- atoms to form corner-sharing TaO6 octahedra. The corner-sharing octahedra tilt angles range from 33–51°. There are a spread of Ta–O bond distances ranging from 1.95–2.05 Å. In the second Ta5+ site, Ta5+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing TaO6 octahedra. The corner-sharing octahedra tilt angles range from 35–51°. There are a spread of Ta–O bond distances ranging from 1.86–2.18 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent Ta5+ atoms. In the second O2- site, O2- is bonded in a 3-coordinate geometry to one Lu3+ and two Ta5+ atoms. In the third O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Lu3+ and two equivalent Ta5+ atoms. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Lu3+ and two equivalent Ta5+ atoms. In the fifth O2- site, O2- is bonded in a bent 150 degrees geometry to two Ta5+ atoms. In the sixth O2- site, O2- is bonded in a distorted trigonal non-coplanar geometry to one Lu3+ and two equivalent Ta5+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sr3Ta4(O6F)2 by Materials Project

Sr3Ta4(O6F)2 crystallizes in the trigonal R-3m space group. The structure is three-dimensional. Sr2+ is bonded to six O2- and two equivalent F1- atoms to form distorted SrO6F2 hexagonal bipyramids that share edges with four equivalent SrO6F2 hexagonal bipyramids and edges with six TaO6 octahedra. There are two shorter (2.70 Å) and four longer (2.73 Å) Sr–O bond lengths. Both Sr–F bond lengths are 2.33 Å. There are two inequivalent Ta5+ sites. In the first Ta5+ site, Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with six TaO6 octahedra and edges with four equivalent SrO6F2 hexagonal bipyramids. The corner-sharing octahedra tilt angles range from 37–42°. All Ta–O bond lengths are 2.01 Å. In the second Ta5+ site, Ta5+ is bonded to six equivalent O2- atoms to form TaO6 octahedra that share corners with six equivalent TaO6 octahedra and edges with six equivalent SrO6F2 hexagonal bipyramids. The corner-sharing octahedral tilt angles are 42°. All Ta–O bond lengths are 2.00 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Sr2+ and two Ta5+ atoms. In the second O2- site, O2- is bonded in a 2-coordinate geometry to one Sr2+ and two equivalent Ta5+ atoms. F1- is bonded in a trigonal non-coplanar geometry to three equivalent Sr2+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on LiTa3O8 by Materials Project

LiTa3O8 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. Li1+ is bonded to six O2- atoms to form distorted LiO6 octahedra that share corners with eight equivalent TaO6 octahedra and edges with two equivalent TaO6 octahedra. The corner-sharing octahedra tilt angles range from 54–62°. There are a spread of Li–O bond distances ranging from 2.13–2.44 Å. There are two inequivalent Ta5+ sites. In the first Ta5+ site, Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with eight equivalent TaO6 octahedra and edges with two equivalent LiO6 octahedra. The corner-sharing octahedra tilt angles range from 41–50°. There are a spread of Ta–O bond distances ranging from 1.97–2.06 Å. In the second Ta5+ site, Ta5+ is bonded to six O2- atoms to form distorted TaO6 octahedra that share corners with four equivalent LiO6 octahedra, corners with four equivalent TaO6 octahedra, and edges with two equivalent TaO6 octahedra. The corner-sharing octahedra tilt angles range from 41–62°. There are a spread of Ta–O bond distances ranging from 1.88–2.30 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to one Li1+ and two Ta5+ atoms. In the second O2- site, O2- is bonded in a trigonal planar geometry to one Li1+ and two equivalent Ta5+ atoms. In the third O2- site, O2- is bonded in a 3-coordinate geometry to one Li1+ and two Ta5+ atoms. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to three Ta5+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on HoTa3O9 by Materials Project

HoTa3O9 crystallizes in the monoclinic P2_1/m space group. The structure is three-dimensional. Ho3+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ho–O bond distances ranging from 2.30–2.51 Å. There are two inequivalent Ta5+ sites. In the first Ta5+ site, Ta5+ is bonded to six O2- atoms to form corner-sharing TaO6 octahedra. The corner-sharing octahedra tilt angles range from 32–50°. There are a spread of Ta–O bond distances ranging from 1.96–2.05 Å. In the second Ta5+ site, Ta5+ is bonded to six O2- atoms to form a mixture of edge and corner-sharing TaO6 octahedra. The corner-sharing octahedra tilt angles range from 34–50°. There are a spread of Ta–O bond distances ranging from 1.86–2.19 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 150 degrees geometry to two equivalent Ta5+ atoms. In the second O2- site, O2- is bonded in a 3-coordinate geometry to one Ho3+ and two Ta5+ atoms. In the third O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Ho3+ and two equivalent Ta5+ atoms. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to one Ho3+ and two equivalent Ta5+ atoms. In the fifth O2- site, O2- is bonded in a bent 150 degrees geometry to two Ta5+ atoms. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to one Ho3+ and two equivalent Ta5+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sr4Ta2O9 by Materials Project

Sr4Ta2O9 is Orthorhombic Perovskite-like structured and crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are five inequivalent Sr2+ sites. In the first Sr2+ site, Sr2+ is bonded to six O2- atoms to form SrO6 octahedra that share corners with six TaO6 octahedra. The corner-sharing octahedra tilt angles range from 30–34°. There are a spread of Sr–O bond distances ranging from 2.41–2.45 Å. In the second Sr2+ site, Sr2+ is bonded to six O2- atoms to form SrO6 octahedra that share corners with six TaO6 octahedra. The corner-sharing octahedra tilt angles range from 31–36°. There are a spread of Sr–O bond distances ranging from 2.42–2.44 Å. In the third Sr2+ site, Sr2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Sr–O bond distances ranging from 2.50–2.91 Å. In the fourth Sr2+ site, Sr2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Sr–O bond distances ranging from 2.49–3.00 Å. In the fifth Sr2+ site, Sr2+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Sr–O bond distances ranging from 2.46–3.07 Å. There are two inequivalent Ta5+ sites. In the first Ta5+ site, Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with three SrO6 octahedra and corners with three TaO6 octahedra. The corner-sharing octahedra tilt angles range from 22–36°. There are a spread of Ta–O bond distances ranging from 1.92–2.19 Å. In the second Ta5+ site, Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with three SrO6 octahedra and corners with three TaO6 octahedra. The corner-sharing octahedra tilt angles range from 25–34°. There are a spread of Ta–O bond distances ranging from 1.94–2.19 Å. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded in a 5-coordinate geometry to three Sr2+ and two equivalent Ta5+ atoms. In the second O2- site, O2- is bonded to two Sr2+ and two Ta5+ atoms to form distorted corner-sharing OSr2Ta2 tetrahedra. In the third O2- site, O2- is bonded in a 4-coordinate geometry to three Sr2+ and one Ta5+ atom. In the fourth O2- site, O2- is bonded in a 5-coordinate geometry to four Sr2+ and one Ta5+ atom. In the fifth O2- site, O2- is bonded in a 1-coordinate geometry to four Sr2+ and one Ta5+ atom. In the sixth O2- site, O2- is bonded in a 1-coordinate geometry to four Sr2+ and one Ta5+ atom. In the seventh O2- site, O2- is bonded to three Sr2+ and one Ta5+ atom to form distorted corner-sharing OSr3Ta tetrahedra. In the eighth O2- site, O2- is bonded in a 4-coordinate geometry to three Sr2+ and one Ta5+ atom. In the ninth O2- site, O2- is bonded in a 5-coordinate geometry to three Sr2+ and two equivalent Ta5+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sr4Ta2O9 by Materials Project

Sr4Ta2O9 is Krennerite-derived structured and crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are five inequivalent Sr2+ sites. In the first Sr2+ site, Sr2+ is bonded in a 3-coordinate geometry to nine O2- atoms. There are a spread of Sr–O bond distances ranging from 2.54–3.24 Å. In the second Sr2+ site, Sr2+ is bonded to six O2- atoms to form SrO6 octahedra that share corners with six equivalent TaO6 octahedra and corners with six equivalent SrO6 pentagonal pyramids. The corner-sharing octahedra tilt angles range from 33–34°. There are four shorter (2.53 Å) and two longer (2.54 Å) Sr–O bond lengths. In the third Sr2+ site, Sr2+ is bonded to six O2- atoms to form SrO6 octahedra that share corners with six equivalent TaO6 octahedra. The corner-sharing octahedra tilt angles range from 34–36°. All Sr–O bond lengths are 2.47 Å. In the fourth Sr2+ site, Sr2+ is bonded to six O2- atoms to form distorted SrO6 pentagonal pyramids that share corners with three equivalent SrO6 octahedra, corners with three equivalent TaO6 octahedra, and edges with three equivalent TaO6 octahedra. The corner-sharing octahedra tilt angles range from 21–70°. There are a spread of Sr–O bond distances ranging from 2.49–2.65 Å. In the fifth Sr2+ site, Sr2+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Sr–O bond distances ranging from 2.44–2.70 Å. There are two inequivalent Ta5+ sites. In the first Ta5+ site, Ta5+ is bonded to six O2- atoms to form distorted TaO6 octahedra that share corners with three equivalent SrO6 octahedra, corners with three equivalent SrO6 pentagonal pyramids, and a faceface with one TaO6 octahedra. The corner-sharing octahedra tilt angles range from 34–36°. There are a spread of Ta–O bond distances ranging from 1.90–2.19 Å. In the second Ta5+ site, Ta5+ is bonded to six O2- atoms to form distorted TaO6 octahedra that share corners with three equivalent SrO6 octahedra, edges with three equivalent SrO6 pentagonal pyramids, and a faceface with one TaO6 octahedra. The corner-sharing octahedra tilt angles range from 33–34°. There are a spread of Ta–O bond distances ranging from 1.92–2.17 Å. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded to three Sr2+ and two Ta5+ atoms to form a mixture of distorted edge and corner-sharing OSr3Ta2 trigonal bipyramids. In the second O2- site, O2- is bonded in a 4-coordinate geometry to three Sr2+ and one Ta5+ atom. In the third O2- site, O2- is bonded in a 1-coordinate geometry to three Sr2+ and one Ta5+ atom. In the fourth O2- site, O2- is bonded in a 4-coordinate geometry to three Sr2+ and one Ta5+ atom. In the fifth O2- site, O2- is bonded in a 1-coordinate geometry to three Sr2+ and one Ta5+ atom. In the sixth O2- site, O2- is bonded to three Sr2+ and two Ta5+ atoms to form a mixture of distorted edge and corner-sharing OSr3Ta2 trigonal bipyramids. In the seventh O2- site, O2- is bonded to three Sr2+ and two Ta5+ atoms to form a mixture of distorted edge and corner-sharing OSr3Ta2 trigonal bipyramids. In the eighth O2- site, O2- is bonded in a 3-coordinate geometry to three Sr2+ and one Ta5+ atom. In the ninth O2- site, O2- is bonded in a 4-coordinate geometry to three Sr2+ and one Ta5+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ca5Ta4O15 by Materials Project

Ca5Ta4O15 crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. there are three inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded in a 9-coordinate geometry to nine equivalent O2- atoms. There are three shorter (2.32 Å) and six longer (2.92 Å) Ca–O bond lengths. In the second Ca2+ site, Ca2+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are three shorter (2.37 Å) and six longer (2.87 Å) Ca–O bond lengths. In the third Ca2+ site, Ca2+ is bonded to twelve O2- atoms to form CaO12 cuboctahedra that share corners with six equivalent CaO12 cuboctahedra and faces with eight TaO6 octahedra. There are six shorter (2.72 Å) and six longer (2.82 Å) Ca–O bond lengths. There are two inequivalent Ta5+ sites. In the first Ta5+ site, Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with six TaO6 octahedra and faces with three equivalent CaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–10°. There is three shorter (1.96 Å) and three longer (2.02 Å) Ta–O bond length. In the second Ta5+ site, Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with three equivalent TaO6 octahedra and a faceface with one CaO12 cuboctahedra. The corner-sharing octahedral tilt angles are 10°. There are three shorter (1.90 Å) and three longer (2.12 Å) Ta–O bond lengths. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to four Ca2+ and one Ta5+ atom. In the second O2- site, O2- is bonded in a distorted linear geometry to two equivalent Ca2+ and two equivalent Ta5+ atoms. In the third O2- site, O2- is bonded in a 2-coordinate geometry to three Ca2+ and two Ta5+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sr5Ta4O15 by Materials Project

Sr5Ta4O15 crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. there are three inequivalent Sr2+ sites. In the first Sr2+ site, Sr2+ is bonded in a 9-coordinate geometry to nine equivalent O2- atoms. There are three shorter (2.54 Å) and six longer (2.93 Å) Sr–O bond lengths. In the second Sr2+ site, Sr2+ is bonded to twelve O2- atoms to form distorted SrO12 cuboctahedra that share corners with nine equivalent SrO12 cuboctahedra, faces with three equivalent SrO12 cuboctahedra, and faces with seven TaO6 octahedra. There are a spread of Sr–O bond distances ranging from 2.55–3.08 Å. In the third Sr2+ site, Sr2+ is bonded to twelve O2- atoms to form SrO12 cuboctahedra that share corners with six equivalent SrO12 cuboctahedra, faces with six equivalent SrO12 cuboctahedra, and faces with eight TaO6 octahedra. There are six shorter (2.77 Å) and six longer (2.86 Å) Sr–O bond lengths. There are two inequivalent Ta5+ sites. In the first Ta5+ site, Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with six TaO6 octahedra and faces with seven SrO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–10°. There are three shorter (1.96 Å) and three longer (2.05 Å) Ta–O bond lengths. In the second Ta5+ site, Ta5+ is bonded to six O2- atoms to form distorted TaO6 octahedra that share corners with three equivalent TaO6 octahedra and faces with four SrO12 cuboctahedra. The corner-sharing octahedral tilt angles are 10°. There are three shorter (1.88 Å) and three longer (2.18 Å) Ta–O bond lengths. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to four Sr2+ and one Ta5+ atom. In the second O2- site, O2- is bonded in a distorted linear geometry to four Sr2+ and two equivalent Ta5+ atoms. In the third O2- site, O2- is bonded in a 2-coordinate geometry to three Sr2+ and two Ta5+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ca4Ta2O9 by Materials Project

Ca3(CaTa2)O9 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are five inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with six TaO6 octahedra. The corner-sharing octahedra tilt angles range from 36–39°. There are two shorter (2.28 Å) and four longer (2.32 Å) Ca–O bond lengths. In the second Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with six TaO6 octahedra. The corner-sharing octahedra tilt angles range from 35–42°. There are a spread of Ca–O bond distances ranging from 2.29–2.31 Å. In the third Ca2+ site, Ca2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ca–O bond distances ranging from 2.36–2.81 Å. In the fourth Ca2+ site, Ca2+ is bonded in a 4-coordinate geometry to eight O2- atoms. There are a spread of Ca–O bond distances ranging from 2.33–2.97 Å. In the fifth Ca2+ site, Ca2+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Ca–O bond distances ranging from 2.30–2.90 Å. There are two inequivalent Ta5+ sites. In the first Ta5+ site, Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with three CaO6 octahedra and corners with three TaO6 octahedra. The corner-sharing octahedra tilt angles range from 28–42°. There are a spread of Ta–O bond distances ranging from 1.92–2.16 Å. In the second Ta5+ site, Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with three CaO6 octahedra and corners with three TaO6 octahedra. The corner-sharing octahedra tilt angles range from 30–39°. There are a spread of Ta–O bond distances ranging from 1.94–2.15 Å. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded in a 5-coordinate geometry to three Ca2+ and two equivalent Ta5+ atoms. In the second O2- site, O2- is bonded to two Ca2+ and two Ta5+ atoms to form distorted corner-sharing OCa2Ta2 tetrahedra. In the third O2- site, O2- is bonded in a 4-coordinate geometry to three Ca2+ and one Ta5+ atom. In the fourth O2- site, O2- is bonded in a 5-coordinate geometry to four Ca2+ and one Ta5+ atom. In the fifth O2- site, O2- is bonded in a 4-coordinate geometry to four Ca2+ and one Ta5+ atom. In the sixth O2- site, O2- is bonded in a 5-coordinate geometry to four Ca2+ and one Ta5+ atom. In the seventh O2- site, O2- is bonded to three Ca2+ and one Ta5+ atom to form distorted corner-sharing OCa3Ta tetrahedra. In the eighth O2- site, O2- is bonded in a 4-coordinate geometry to three Ca2+ and one Ta5+ atom. In the ninth O2- site, O2- is bonded in a 5-coordinate geometry to three Ca2+ and two equivalent Ta5+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ca4Ta2O9 by Materials Project

Ca3(CaTa2)O9 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are five inequivalent Ca2+ sites. In the first Ca2+ site, Ca2+ is bonded in a 3-coordinate geometry to five O2- atoms. There are a spread of Ca–O bond distances ranging from 2.33–2.86 Å. In the second Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with six equivalent CaO6 octahedra and corners with six equivalent TaO6 octahedra. The corner-sharing octahedra tilt angles range from 41–62°. There are two shorter (2.37 Å) and four longer (2.38 Å) Ca–O bond lengths. In the third Ca2+ site, Ca2+ is bonded to six O2- atoms to form CaO6 octahedra that share corners with six equivalent TaO6 octahedra. The corner-sharing octahedra tilt angles range from 35–37°. There are a spread of Ca–O bond distances ranging from 2.29–2.31 Å. In the fourth Ca2+ site, Ca2+ is bonded to six O2- atoms to form distorted CaO6 octahedra that share corners with three equivalent CaO6 octahedra, corners with three equivalent TaO6 octahedra, and edges with three equivalent TaO6 octahedra. The corner-sharing octahedra tilt angles range from 29–62°. There are a spread of Ca–O bond distances ranging from 2.34–2.43 Å. In the fifth Ca2+ site, Ca2+ is bonded in a distorted trigonal planar geometry to three O2- atoms. All Ca–O bond lengths are 2.25 Å. There are two inequivalent Ta5+ sites. In the first Ta5+ site, Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with six CaO6 octahedra and a faceface with one TaO6 octahedra. The corner-sharing octahedra tilt angles range from 29–37°. There are a spread of Ta–O bond distances ranging from 1.92–2.12 Å. In the second Ta5+ site, Ta5+ is bonded to six O2- atoms to form distorted TaO6 octahedra that share corners with three equivalent CaO6 octahedra, edges with three equivalent CaO6 octahedra, and a faceface with one TaO6 octahedra. The corner-sharing octahedra tilt angles range from 41–42°. There are a spread of Ta–O bond distances ranging from 1.90–2.21 Å. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to two Ca2+ and two Ta5+ atoms. In the second O2- site, O2- is bonded in a 4-coordinate geometry to two Ca2+ and one Ta5+ atom. In the third O2- site, O2- is bonded in a 3-coordinate geometry to two Ca2+ and one Ta5+ atom. In the fourth O2- site, O2- is bonded in a 4-coordinate geometry to three Ca2+ and one Ta5+ atom. In the fifth O2- site, O2- is bonded in a 3-coordinate geometry to two Ca2+ and one Ta5+ atom. In the sixth O2- site, O2- is bonded in a 4-coordinate geometry to two Ca2+ and two Ta5+ atoms. In the seventh O2- site, O2- is bonded in a 4-coordinate geometry to two Ca2+ and two Ta5+ atoms. In the eighth O2- site, O2- is bonded in a 3-coordinate geometry to two Ca2+ and one Ta5+ atom. In the ninth O2- site, O2- is bonded in a 4-coordinate geometry to three Ca2+ and one Ta5+ atom.

36 MATERIALS SCIENCE↗