DOI: 10.17188/1710111
title: Materials Data on Ce2MgSe4 by Materials Project

description: MgCe2Se4 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 Se2- atoms to form MgSe6 octahedra that share a cornercorner with one CeSe6 octahedra, corners with two equivalent MgSe6 octahedra, corners with four CeSe7 pentagonal bipyramids, an edgeedge with one MgSe6 octahedra, edges with four CeSe6 octahedra, and edges with three CeSe7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 11–53°. There are a spread of Mg–Se bond distances ranging from 2.69–3.09 Å. In the second Mg2+ site, Mg2+ is bonded to six Se2- atoms to form MgSe6 octahedra that share a cornercorner with one CeSe6 octahedra, corners with two equivalent MgSe6 octahedra, corners with four CeSe7 pentagonal bipyramids, an edgeedge with one MgSe6 octahedra, edges with four CeSe6 octahedra, and edges with three CeSe7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 11–53°. There are a spread of Mg–Se bond distances ranging from 2.69–2.98 Å. There are four inequivalent Ce3+ sites. In the first Ce3+ site, Ce3+ is bonded to six Se2- atoms to form CeSe6 octahedra that share a cornercorner with one MgSe6 octahedra, corners with two equivalent CeSe6 octahedra, corners with four CeSe7 pentagonal bipyramids, an edgeedge with one CeSe6 octahedra, edges with four MgSe6 octahedra, and edges with three CeSe7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 10–53°. There are a spread of Ce–Se bond distances ranging from 2.92–2.97 Å. In the second Ce3+ site, Ce3+ is bonded to six Se2- atoms to form CeSe6 octahedra that share a cornercorner with one MgSe6 octahedra, corners with two equivalent CeSe6 octahedra, corners with four CeSe7 pentagonal bipyramids, an edgeedge with one CeSe6 octahedra, edges with four MgSe6 octahedra, and edges with three CeSe7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 10–53°. There are a spread of Ce–Se bond distances ranging from 2.91–3.01 Å. In the third Ce3+ site, Ce3+ is bonded to seven Se2- atoms to form distorted CeSe7 pentagonal bipyramids that share corners with four MgSe6 octahedra, corners with four CeSe6 octahedra, edges with three MgSe6 octahedra, edges with three CeSe6 octahedra, and faces with two equivalent CeSe7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 14–71°. There are a spread of Ce–Se bond distances ranging from 2.98–3.27 Å. In the fourth Ce3+ site, Ce3+ is bonded to seven Se2- atoms to form distorted CeSe7 pentagonal bipyramids that share corners with four MgSe6 octahedra, corners with four CeSe6 octahedra, edges with three MgSe6 octahedra, edges with three CeSe6 octahedra, and faces with two equivalent CeSe7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 16–70°. There are a spread of Ce–Se bond distances ranging from 2.96–3.30 Å. There are eight inequivalent Se2- sites. In the first Se2- site, Se2- is bonded to two Mg2+ and three Ce3+ atoms to form distorted SeCe3Mg2 trigonal bipyramids that share corners with two equivalent SeCe3Mg2 square pyramids, corners with three equivalent SeCe3Mg tetrahedra, corners with two equivalent SeCe3Mg2 trigonal bipyramids, edges with five SeCe3Mg2 square pyramids, and edges with three SeCe3Mg2 trigonal bipyramids. In the second Se2- site, Se2- is bonded to two Mg2+ and three Ce3+ atoms to form distorted SeCe3Mg2 trigonal bipyramids that share corners with six SeCe3Mg2 square pyramids, corners with two equivalent SeCe3Mg tetrahedra, corners with two equivalent SeCe3Mg2 trigonal bipyramids, edges with three SeCe3Mg2 square pyramids, an edgeedge with one SeCe3Mg tetrahedra, and edges with three SeCe3Mg2 trigonal bipyramids. In the third Se2- site, Se2- is bonded to one Mg2+ and three Ce3+ atoms to form a mixture of distorted edge and corner-sharing SeCe3Mg tetrahedra. In the fourth Se2- site, Se2- is bonded in a distorted rectangular see-saw-like geometry to one Mg2+ and three Ce3+ atoms. In the fifth Se2- site, Se2- is bonded to two Mg2+ and three Ce3+ atoms to form distorted SeCe3Mg2 square pyramids that share a cornercorner with one SeCe3Mg tetrahedra, corners with eight SeCe3Mg2 trigonal bipyramids, edges with four SeCe3Mg2 square pyramids, an edgeedge with one SeCe3Mg tetrahedra, and edges with two SeCe3Mg2 trigonal bipyramids. In the sixth Se2- site, Se2- is bonded to two Mg2+ and three Ce3+ atoms to form SeCe3Mg2 square pyramids that share corners with two equivalent SeCe4Mg square pyramids, a cornercorner with one SeCe3Mg tetrahedra, corners with six SeCe3Mg2 trigonal bipyramids, edges with three SeCe3Mg2 square pyramids, an edgeedge with one SeCe3Mg tetrahedra, and edges with three SeCe3Mg2 trigonal bipyramids. In the seventh Se2- site, Se2- is bonded to one Mg2+ and four Ce3+ atoms to form distorted SeCe4Mg square pyramids that share corners with two equivalent SeCe3Mg2 square pyramids, corners with two equivalent SeCe3Mg tetrahedra, corners with two equivalent SeCe4Mg trigonal bipyramids, edges with three SeCe3Mg2 square pyramids, an edgeedge with one SeCe3Mg tetrahedra, and edges with five SeCe3Mg2 trigonal bipyramids. In the eighth Se2- site, Se2- is bonded to one Mg2+ and four Ce3+ atoms to form distorted SeCe4Mg trigonal bipyramids that share corners with eight SeCe3Mg2 square pyramids, corners with three equivalent SeCe3Mg tetrahedra, edges with two SeCe3Mg2 square pyramids, and edges with four SeCe3Mg2 trigonal bipyramids.