DOI: 10.17188/1705420
title: Materials Data on Ho2MgSe4 by Materials Project

description: MgHo2Se4 crystallizes in the triclinic P-1 space group. The structure is two-dimensional and consists of one MgHo2Se4 sheet oriented in the (0, 0, 1) direction. there are two inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to four Se2- atoms to form MgSe4 tetrahedra that share a cornercorner with one MgSe6 octahedra, corners with two equivalent HoSe6 octahedra, and corners with six HoSe4 tetrahedra. The corner-sharing octahedra tilt angles range from 58–60°. There are a spread of Mg–Se bond distances ranging from 2.57–2.61 Å. In the second Mg2+ site, Mg2+ is bonded to six Se2- atoms to form MgSe6 octahedra that share a cornercorner with one MgSe4 tetrahedra, corners with five HoSe4 tetrahedra, edges with two equivalent MgSe6 octahedra, and edges with four equivalent HoSe6 octahedra. There are a spread of Mg–Se bond distances ranging from 2.80–2.85 Å. There are four inequivalent Ho3+ sites. In the first Ho3+ site, Ho3+ is bonded to four Se2- atoms to form HoSe4 tetrahedra that share a cornercorner with one HoSe6 octahedra, corners with two equivalent MgSe6 octahedra, corners with two equivalent MgSe4 tetrahedra, and corners with four HoSe4 tetrahedra. The corner-sharing octahedra tilt angles range from 58–62°. There are a spread of Ho–Se bond distances ranging from 2.69–2.73 Å. In the second Ho3+ site, Ho3+ is bonded to six Se2- atoms to form HoSe6 octahedra that share corners with two equivalent MgSe4 tetrahedra, corners with four HoSe4 tetrahedra, edges with two equivalent HoSe6 octahedra, and edges with four equivalent MgSe6 octahedra. There are a spread of Ho–Se bond distances ranging from 2.86–2.94 Å. In the third Ho3+ site, Ho3+ is bonded to four Se2- atoms to form HoSe4 tetrahedra that share a cornercorner with one HoSe6 octahedra, corners with two equivalent MgSe6 octahedra, corners with two equivalent MgSe4 tetrahedra, and corners with four HoSe4 tetrahedra. The corner-sharing octahedra tilt angles range from 58–64°. There are a spread of Ho–Se bond distances ranging from 2.69–2.74 Å. In the fourth Ho3+ site, Ho3+ is bonded to four Se2- atoms to form HoSe4 tetrahedra that share a cornercorner with one MgSe6 octahedra, corners with two equivalent HoSe6 octahedra, corners with two equivalent MgSe4 tetrahedra, and corners with four HoSe4 tetrahedra. The corner-sharing octahedra tilt angles range from 58–62°. There are a spread of Ho–Se bond distances ranging from 2.70–2.73 Å. There are eight inequivalent Se2- sites. In the first Se2- site, Se2- is bonded to two equivalent Mg2+ and two Ho3+ atoms to form distorted SeHo2Mg2 tetrahedra that share corners with seven SeHo3Mg tetrahedra, corners with two equivalent SeHo2Mg2 trigonal pyramids, edges with two SeHo2Mg2 tetrahedra, and an edgeedge with one SeHo2Mg2 trigonal pyramid. In the second Se2- site, Se2- is bonded to two Mg2+ and two equivalent Ho3+ atoms to form distorted SeHo2Mg2 trigonal pyramids that share corners with nine SeHo2Mg2 tetrahedra, edges with two SeHo3Mg tetrahedra, and an edgeedge with one SeHo2Mg2 trigonal pyramid. In the third Se2- site, Se2- is bonded in a trigonal non-coplanar geometry to one Mg2+ and two Ho3+ atoms. In the fourth Se2- site, Se2- is bonded in a trigonal non-coplanar geometry to three Ho3+ atoms. In the fifth Se2- site, Se2- is bonded in a trigonal non-coplanar geometry to one Mg2+ and two Ho3+ atoms. In the sixth Se2- site, Se2- is bonded in a trigonal non-coplanar geometry to one Mg2+ and two Ho3+ atoms. In the seventh Se2- site, Se2- is bonded to one Mg2+ and three Ho3+ atoms to form distorted SeHo3Mg tetrahedra that share corners with six SeHo2Mg2 tetrahedra, corners with three equivalent SeHo2Mg2 trigonal pyramids, edges with two SeHo3Mg tetrahedra, and an edgeedge with one SeHo2Mg2 trigonal pyramid. In the eighth Se2- site, Se2- is bonded to two equivalent Mg2+ and two Ho3+ atoms to form distorted SeHo2Mg2 tetrahedra that share corners with five SeHo2Mg2 tetrahedra, corners with four equivalent SeHo2Mg2 trigonal pyramids, and edges with three SeHo3Mg tetrahedra.