Materials Data on Sm3Ti3(SeO4)2 by Materials Project
Sm3Ti3Se2O8 crystallizes in the monoclinic P2_1/m space group. The structure is three-dimensional. there are three inequivalent Sm+2.67+ sites. In the first Sm+2.67+ site, Sm+2.67+ is bonded in a 4-coordinate geometry to four Se2- and four O2- atoms. All Sm–Se bond lengths are 3.08 Å. There are a spread of Sm–O bond distances ranging from 2.39–2.41 Å. In the second Sm+2.67+ site, Sm+2.67+ is bonded in a 9-coordinate geometry to two equivalent Se2- and seven O2- atoms. Both Sm–Se bond lengths are 3.04 Å. There are a spread of Sm–O bond distances ranging from 2.40–2.58 Å. In the third Sm+2.67+ site, Sm+2.67+ is bonded in a 7-coordinate geometry to four Se2- and three O2- atoms. There are a spread of Sm–Se bond distances ranging from 2.99–3.15 Å. There are two shorter (2.29 Å) and one longer (2.41 Å) Sm–O bond lengths. There are three inequivalent Ti4+ sites. In the first Ti4+ site, Ti4+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Ti–O bond distances ranging from 1.80–2.01 Å. In the second Ti4+ site, Ti4+ is bonded to one Se2- and five O2- atoms to form distorted TiSeO5 trigonal bipyramids that share corners with two equivalent TiSeO5 trigonal bipyramids and an edgeedge with one TiO6 octahedra. The Ti–Se bond length is 3.05 Å. There are a spread of Ti–O bond distances ranging from 1.82–2.03 Å. In the third Ti4+ site, Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share corners with two equivalent TiO6 octahedra, edges with two equivalent TiO6 octahedra, and an edgeedge with one TiSeO5 trigonal bipyramid. The corner-sharing octahedral tilt angles are 27°. There are a spread of Ti–O bond distances ranging from 1.94–2.13 Å. There are two inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a 5-coordinate geometry to five Sm+2.67+, one Ti4+, and two equivalent O2- atoms. Both Se–O bond lengths are 3.30 Å. In the second Se2- site, Se2- is bonded to five Sm+2.67+ atoms to form distorted SeSm5 square pyramids that share corners with four equivalent OSm3Ti tetrahedra, edges with four equivalent SeSm5 square pyramids, and an edgeedge with one OSm3Ti tetrahedra. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to three equivalent Sm+2.67+ and one Ti4+ atom. In the second O2- site, O2- is bonded in a 4-coordinate geometry to one Sm+2.67+ and three Ti4+ atoms. In the third O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Sm+2.67+ and two Ti4+ atoms. In the fourth O2- site, O2- is bonded in a 3-coordinate geometry to one Sm+2.67+ and two Ti4+ atoms. In the fifth O2- site, O2- is bonded to three equivalent Sm+2.67+ and one Ti4+ atom to form distorted OSm3Ti tetrahedra that share corners with four equivalent SeSm5 square pyramids, corners with two equivalent OSm3Ti tetrahedra, an edgeedge with one SeSm5 square pyramid, and edges with two equivalent OSm3Ti tetrahedra. In the sixth O2- site, O2- is bonded in a 4-coordinate geometry to two Sm+2.67+ and two equivalent Ti4+ atoms. In the seventh O2- site, O2- is bonded to four Ti4+ atoms to form a mixture of distorted corner and edge-sharing OTi4 tetrahedra. In the eighth O2- site, O2- is bonded in a distorted trigonal planar geometry to two equivalent Sm+2.67+, one Ti4+, and two equivalent Se2- atoms.