Materials Data on Sm2MgS4 by Materials Project
MgSm2S4 crystallizes in the orthorhombic Pca2_1 space group. The structure is three-dimensional. there are two inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to six S2- atoms to form MgS6 octahedra that share a cornercorner with one SmS6 octahedra, corners with two equivalent MgS6 octahedra, corners with four SmS7 pentagonal bipyramids, an edgeedge with one MgS6 octahedra, edges with four SmS6 octahedra, and edges with three SmS7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 11–54°. There are a spread of Mg–S bond distances ranging from 2.54–2.92 Å. In the second Mg2+ site, Mg2+ is bonded to six S2- atoms to form MgS6 octahedra that share a cornercorner with one SmS6 octahedra, corners with two equivalent MgS6 octahedra, corners with four SmS7 pentagonal bipyramids, an edgeedge with one MgS6 octahedra, edges with four SmS6 octahedra, and edges with three SmS7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 11–54°. There are a spread of Mg–S bond distances ranging from 2.55–2.81 Å. There are four inequivalent Sm3+ sites. In the first Sm3+ site, Sm3+ is bonded to six S2- atoms to form SmS6 octahedra that share a cornercorner with one MgS6 octahedra, corners with two equivalent SmS6 octahedra, corners with four SmS7 pentagonal bipyramids, an edgeedge with one SmS6 octahedra, edges with four MgS6 octahedra, and edges with three SmS7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 11–54°. There are a spread of Sm–S bond distances ranging from 2.74–2.82 Å. In the second Sm3+ site, Sm3+ is bonded to six S2- atoms to form SmS6 octahedra that share a cornercorner with one MgS6 octahedra, corners with two equivalent SmS6 octahedra, corners with four SmS7 pentagonal bipyramids, an edgeedge with one SmS6 octahedra, edges with four MgS6 octahedra, and edges with three SmS7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 11–54°. There are a spread of Sm–S bond distances ranging from 2.73–2.84 Å. In the third Sm3+ site, Sm3+ is bonded to seven S2- atoms to form distorted SmS7 pentagonal bipyramids that share corners with four MgS6 octahedra, corners with four SmS6 octahedra, edges with three MgS6 octahedra, edges with three SmS6 octahedra, and faces with two equivalent SmS7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 15–71°. There are a spread of Sm–S bond distances ranging from 2.78–3.08 Å. In the fourth Sm3+ site, Sm3+ is bonded to seven S2- atoms to form distorted SmS7 pentagonal bipyramids that share corners with four MgS6 octahedra, corners with four SmS6 octahedra, edges with three MgS6 octahedra, edges with three SmS6 octahedra, and faces with two equivalent SmS7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 17–70°. There are a spread of Sm–S bond distances ranging from 2.77–3.09 Å. There are eight inequivalent S2- sites. In the first S2- site, S2- is bonded to two Mg2+ and three Sm3+ atoms to form distorted SSm3Mg2 trigonal bipyramids that share corners with two equivalent SSm3Mg2 square pyramids, corners with three equivalent SSm3Mg tetrahedra, corners with two equivalent SSm3Mg2 trigonal bipyramids, edges with five SSm3Mg2 square pyramids, and edges with three SSm3Mg2 trigonal bipyramids. In the second S2- site, S2- is bonded to two Mg2+ and three Sm3+ atoms to form distorted SSm3Mg2 trigonal bipyramids that share corners with six SSm3Mg2 square pyramids, corners with two equivalent SSm3Mg tetrahedra, corners with two equivalent SSm3Mg2 trigonal bipyramids, edges with three SSm3Mg2 square pyramids, an edgeedge with one SSm3Mg tetrahedra, and edges with three SSm3Mg2 trigonal bipyramids. In the third S2- site, S2- is bonded to one Mg2+ and three Sm3+ atoms to form a mixture of distorted edge and corner-sharing SSm3Mg tetrahedra. In the fourth S2- site, S2- is bonded in a distorted rectangular see-saw-like geometry to one Mg2+ and three Sm3+ atoms. In the fifth S2- site, S2- is bonded to two Mg2+ and three Sm3+ atoms to form distorted SSm3Mg2 square pyramids that share a cornercorner with one SSm3Mg tetrahedra, corners with eight SSm3Mg2 trigonal bipyramids, edges with four SSm3Mg2 square pyramids, an edgeedge with one SSm3Mg tetrahedra, and edges with two SSm3Mg2 trigonal bipyramids. In the sixth S2- site, S2- is bonded to two Mg2+ and three Sm3+ atoms to form distorted SSm3Mg2 square pyramids that share corners with two equivalent SSm4Mg square pyramids, a cornercorner with one SSm3Mg tetrahedra, corners with six SSm3Mg2 trigonal bipyramids, edges with three SSm3Mg2 square pyramids, an edgeedge with one SSm3Mg tetrahedra, and edges with three SSm3Mg2 trigonal bipyramids. In the seventh S2- site, S2- is bonded to one Mg2+ and four Sm3+ atoms to form distorted SSm4Mg square pyramids that share corners with two equivalent SSm3Mg2 square pyramids, corners with two equivalent SSm3Mg tetrahedra, corners with two equivalent SSm4Mg trigonal bipyramids, edges with three SSm3Mg2 square pyramids, an edgeedge with one SSm3Mg tetrahedra, and edges with five SSm3Mg2 trigonal bipyramids. In the eighth S2- site, S2- is bonded to one Mg2+ and four Sm3+ atoms to form distorted SSm4Mg trigonal bipyramids that share corners with eight SSm3Mg2 square pyramids, corners with three equivalent SSm3Mg tetrahedra, edges with two SSm3Mg2 square pyramids, and edges with four SSm3Mg2 trigonal bipyramids.