Materials Data on Mg(ScSe2)2 by Materials Project

Abstract

Mg(ScSe2)2 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Mg2+ is bonded to seven Se2- atoms to form distorted MgSe7 pentagonal bipyramids that share corners with eight ScSe6 octahedra, edges with five ScSe6 octahedra, edges with two equivalent MgSe7 pentagonal bipyramids, and faces with two equivalent MgSe7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 12–64°. There are a spread of Mg–Se bond distances ranging from 2.76–3.09 Å. There are two inequivalent Sc3+ sites. In the first Sc3+ site, Sc3+ is bonded to six Se2- atoms to form ScSe6 octahedra that share corners with three equivalent ScSe6 octahedra, corners with four equivalent MgSe7 pentagonal bipyramids, edges with six ScSe6 octahedra, and an edgeedge with one MgSe7 pentagonal bipyramid. The corner-sharing octahedra tilt angles range from 51–59°. There are a spread of Sc–Se bond distances ranging from 2.68–2.82 Å. In the second Sc3+ site, Sc3+ is bonded to six Se2- atoms to form ScSe6 octahedra that share corners with three equivalent ScSe6 octahedra, corners with four equivalent MgSe7 pentagonal bipyramids, edges with four ScSe6 octahedra, and edges with four equivalent MgSe7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 51–59°. There are a spread of Sc–Se bond distances ranging from 2.69–2.75 Å. There are four inequivalent Se2- sites. In the first Se2- site, Se2- is bonded to three equivalent Mg2+ and two equivalent Sc3+ atoms to form a mixture of edge and corner-sharing SeMg3Sc2 square pyramids. In the second Se2- site, Se2- is bonded in a rectangular see-saw-like geometry to four Sc3+ atoms. In the third Se2- site, Se2- is bonded to two equivalent Mg2+ and three Sc3+ atoms to form a mixture of distorted edge and corner-sharing SeMg2Sc3 trigonal bipyramids. In the fourth Se2- site, Se2- is bonded to two equivalent Mg2+ and three Sc3+ atoms to form SeMg2Sc3 square pyramids that share corners with two equivalent SeMg3Sc2 square pyramids, corners with two equivalent SeMg2Sc3 trigonal bipyramids, edges with five SeMg2Sc3 square pyramids, and edges with three equivalent SeMg2Sc3 trigonal bipyramids.