Materials Data on Sm6Ta2Ti4O21 by Materials Project
Sm6Ti4Ta2O21 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. there are four inequivalent Sm3+ sites. In the first Sm3+ site, Sm3+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are a spread of Sm–O bond distances ranging from 2.26–2.65 Å. In the second Sm3+ site, Sm3+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are a spread of Sm–O bond distances ranging from 2.26–2.55 Å. In the third Sm3+ site, Sm3+ is bonded to eight O2- atoms to form distorted SmO8 hexagonal bipyramids that share edges with two SmO8 hexagonal bipyramids, edges with three TiO6 octahedra, and edges with three equivalent TaO6 octahedra. There are a spread of Sm–O bond distances ranging from 2.24–2.63 Å. In the fourth Sm3+ site, Sm3+ is bonded to eight O2- atoms to form distorted SmO8 hexagonal bipyramids that share edges with two equivalent SmO8 hexagonal bipyramids, edges with two equivalent TaO6 octahedra, and edges with four TiO6 octahedra. There are a spread of Sm–O bond distances ranging from 2.25–2.57 Å. There are three inequivalent Ti4+ sites. In the first Ti4+ site, Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with two equivalent TaO6 octahedra, corners with four TiO6 octahedra, and edges with four SmO8 hexagonal bipyramids. The corner-sharing octahedra tilt angles range from 49–53°. There are two shorter (2.02 Å) and four longer (2.04 Å) Ti–O bond lengths. In the second Ti4+ site, Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with two equivalent TaO6 octahedra, corners with four TiO6 octahedra, and edges with two equivalent SmO8 hexagonal bipyramids. The corner-sharing octahedra tilt angles range from 50–54°. There are a spread of Ti–O bond distances ranging from 2.03–2.06 Å. In the third Ti4+ site, Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with three TiO6 octahedra, corners with three equivalent TaO6 octahedra, and edges with two SmO8 hexagonal bipyramids. The corner-sharing octahedra tilt angles range from 42–54°. There are a spread of Ti–O bond distances ranging from 1.96–2.11 Å. Ta4+ is bonded to six O2- atoms to form TaO6 octahedra that share a cornercorner with one TaO6 octahedra, corners with five TiO6 octahedra, and edges with four SmO8 hexagonal bipyramids. The corner-sharing octahedra tilt angles range from 45–50°. There are a spread of Ta–O bond distances ranging from 1.96–2.04 Å. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded to two Sm3+ and two Ti4+ atoms to form distorted OSm2Ti2 tetrahedra that share corners with six OSm2Ti2 tetrahedra and edges with three OSm4 tetrahedra. In the second O2- site, O2- is bonded in a 2-coordinate geometry to two Sm3+, one Ti4+, and one Ta4+ atom. In the third O2- site, O2- is bonded in a 4-coordinate geometry to two Sm3+, one Ti4+, and one Ta4+ atom. In the fourth O2- site, O2- is bonded to four Sm3+ atoms to form a mixture of edge and corner-sharing OSm4 tetrahedra. In the fifth O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Sm3+ and two equivalent Ti4+ atoms. In the sixth O2- site, O2- is bonded to two Sm3+ and two Ti4+ atoms to form a mixture of distorted edge and corner-sharing OSm2Ti2 tetrahedra. In the seventh O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Sm3+ and two equivalent Ta4+ atoms. In the eighth O2- site, O2- is bonded in a 4-coordinate geometry to two Sm3+, one Ti4+, and one Ta4+ atom. In the ninth O2- site, O2- is bonded to four Sm3+ atoms to form OSm4 tetrahedra that share corners with eight OSm4 tetrahedra and edges with two equivalent OSm2Ti2 tetrahedra. In the tenth O2- site, O2- is bonded in a 4-coordinate geometry to two Sm3+, one Ti4+, and one Ta4+ atom. In the eleventh O2- site, O2- is bonded in a 4-coordinate geometry to two Sm3+, one Ti4+, and one Ta4+ atom. In the twelfth O2- site, O2- is bonded to two Sm3+ and two Ti4+ atoms to form a mixture of distorted edge and corner-sharing OSm2Ti2 tetrahedra.