Materials Data on Sm2MgSe4 by Materials Project

Abstract

MgSm2Se4 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Mg2+ is bonded to five Se2- atoms to form MgSe5 square pyramids that share corners with four SmSe6 octahedra, edges with four SmSe6 octahedra, and edges with four equivalent MgSe5 square pyramids. The corner-sharing octahedra tilt angles range from 4–5°. There are a spread of Mg–Se bond distances ranging from 2.66–2.77 Å. There are two inequivalent Sm3+ sites. In the first Sm3+ site, Sm3+ is bonded to six Se2- atoms to form SmSe6 octahedra that share corners with three equivalent SmSe6 octahedra, corners with two equivalent MgSe5 square pyramids, edges with six SmSe6 octahedra, and an edgeedge with one MgSe5 square pyramid. The corner-sharing octahedra tilt angles range from 52–59°. There are a spread of Sm–Se bond distances ranging from 2.88–3.01 Å. In the second Sm3+ site, Sm3+ is bonded to six Se2- atoms to form SmSe6 octahedra that share corners with three equivalent SmSe6 octahedra, corners with two equivalent MgSe5 square pyramids, edges with four SmSe6 octahedra, and edges with three equivalent MgSe5 square pyramids. The corner-sharing octahedra tilt angles range from 52–59°. There are a spread of Sm–Se bond distances ranging from 2.82–3.04 Å. There are four inequivalent Se2- sites. In the first Se2- site, Se2- is bonded to three equivalent Mg2+ and two equivalent Sm3+ atoms to form a mixture of edge and corner-sharing SeSm2Mg3 square pyramids. In the second Se2- site, Se2- is bonded in a rectangular see-saw-like geometry to four Sm3+ atoms. In the third Se2- site, Se2- is bonded in a 3-coordinate geometry to three Sm3+ atoms. In the fourth Se2- site, Se2- is bonded to two equivalent Mg2+ and three Sm3+ atoms to form SeSm3Mg2 square pyramids that share corners with two equivalent SeSm2Mg3 square pyramids and edges with five SeSm3Mg2 square pyramids.