Materials Data on K3SmSi2O7 by Materials Project

Abstract

K3SmSi2O7 crystallizes in the hexagonal P6_3/mcm space group. The structure is three-dimensional. there are three inequivalent K1+ sites. In the first K1+ site, K1+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of K–O bond distances ranging from 2.81–3.09 Å. In the second K1+ site, K1+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are six shorter (2.96 Å) and three longer (3.07 Å) K–O bond lengths. In the third K1+ site, K1+ is bonded in a 6-coordinate geometry to six equivalent O2- atoms. All K–O bond lengths are 2.79 Å. There are two inequivalent Sm3+ sites. In the first Sm3+ site, Sm3+ is bonded to six equivalent O2- atoms to form distorted SmO6 pentagonal pyramids that share corners with six equivalent SiO4 tetrahedra. All Sm–O bond lengths are 2.36 Å. In the second Sm3+ site, Sm3+ is bonded to six equivalent O2- atoms to form SmO6 octahedra that share corners with six equivalent SiO4 tetrahedra. All Sm–O bond lengths are 2.32 Å. Si4+ is bonded to four O2- atoms to form SiO4 tetrahedra that share corners with two equivalent SmO6 octahedra, a cornercorner with one SmO6 pentagonal pyramid, and a cornercorner with one SiO4 tetrahedra. The corner-sharing octahedral tilt angles are 13°. There is three shorter (1.64 Å) and one longer (1.69 Å) Si–O bond length. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to four K1+, one Sm3+, and one Si4+ atom. In the second O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two equivalent K1+ and two equivalent Si4+ atoms. In the third O2- site, O2- is bonded in a 1-coordinate geometry to three K1+, one Sm3+, and one Si4+ atom.