Materials Data on Ce2MgSe4 by Materials Project

Abstract

MgCe2Se4 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 CeSe6 octahedra and edges with three CeSe6 octahedra. The corner-sharing octahedra tilt angles range from 59–63°. There are a spread of Mg–Se bond distances ranging from 2.56–2.62 Å. There are two inequivalent Ce3+ sites. In the first Ce3+ site, Ce3+ is bonded to six Se2- atoms to form CeSe6 octahedra that share corners with four equivalent CeSe6 octahedra, corners with two equivalent MgSe4 tetrahedra, edges with four CeSe6 octahedra, and edges with two equivalent MgSe4 tetrahedra. The corner-sharing octahedra tilt angles range from 52–56°. There are four shorter (2.97 Å) and two longer (3.01 Å) Ce–Se bond lengths. In the second Ce3+ site, Ce3+ is bonded to six Se2- atoms to form CeSe6 octahedra that share corners with eight CeSe6 octahedra, corners with four equivalent MgSe4 tetrahedra, edges with two equivalent CeSe6 octahedra, and an edgeedge with one MgSe4 tetrahedra. The corner-sharing octahedra tilt angles range from 47–56°. There are a spread of Ce–Se bond distances ranging from 2.97–3.04 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 Ce3+ atoms. In the second Se2- site, Se2- is bonded in a rectangular see-saw-like geometry to one Mg2+ and three Ce3+ atoms. In the third Se2- site, Se2- is bonded to one Mg2+ and three Ce3+ atoms to form distorted corner-sharing SeCe3Mg trigonal pyramids.