Materials Data on Sm2MgSe4 by Materials Project

MgSm2Se4 is Spinel-like structured and crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Mg2+ is bonded to four Se2- atoms to form MgSe4 tetrahedra that share corners with six SmSe6 octahedra and edges with three SmSe6 octahedra. The corner-sharing octahedra tilt angles range from 59–64°. There are a spread of Mg–Se bond distances ranging from 2.54–2.62 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 four equivalent SmSe6 octahedra, corners with two equivalent MgSe4 tetrahedra, edges with four SmSe6 octahedra, and edges with two equivalent MgSe4 tetrahedra. The corner-sharing octahedra tilt angles range from 51–55°. There are a spread of Sm–Se bond distances ranging from 2.91–2.97 Å. In the second Sm3+ site, Sm3+ is bonded to six Se2- atoms to form SmSe6 octahedra that share corners with eight SmSe6 octahedra, corners with four equivalent MgSe4 tetrahedra, edges with two equivalent SmSe6 octahedra, and an edgeedge with one MgSe4 tetrahedra. The corner-sharing octahedra tilt angles range from 46–55°. There are a spread of Sm–Se bond distances ranging from 2.91–2.98 Å. There are three inequivalent Se2- sites. In the first Se2- site, Se2- is bonded in a rectangular see-saw-like geometry to one Mg2+ and three Sm3+ atoms. In the second Se2- site, Se2- is bonded in a rectangular see-saw-like geometry to one Mg2+ and three Sm3+ atoms. In the third Se2- site, Se2- is bonded to one Mg2+ and three Sm3+ atoms to form distorted corner-sharing SeSm3Mg trigonal pyramids.