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DOE OSTI2020

Materials Data on Er2MgSe4 by Materials Project

MgEr2Se4 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Mg2+ is bonded to five Se2- atoms to form MgSe5 square pyramids that share corners with four ErSe6 octahedra, edges with four ErSe6 octahedra, and edges with four equivalent MgSe5 square pyramids. The corner-sharing octahedra tilt angles range from 6–11°. There are three shorter (2.75 Å) and two longer (2.81 Å) Mg–Se bond lengths. There are two inequivalent Er3+ sites. In the first Er3+ site, Er3+ is bonded to six Se2- atoms to form ErSe6 octahedra that share corners with three equivalent ErSe6 octahedra, corners with two equivalent MgSe5 square pyramids, edges with six ErSe6 octahedra, and an edgeedge with one MgSe5 square pyramid. The corner-sharing octahedra tilt angles range from 52–59°. There are a spread of Er–Se bond distances ranging from 2.82–2.92 Å. In the second Er3+ site, Er3+ is bonded to six Se2- atoms to form ErSe6 octahedra that share corners with three equivalent ErSe6 octahedra, corners with two equivalent MgSe5 square pyramids, edges with four ErSe6 octahedra, and edges with three equivalent MgSe5 square pyramids. The corner-sharing octahedra tilt angles range from 52–59°. There are a spread of Er–Se bond distances ranging from 2.78–2.90 Å. There are four inequivalent Se2- sites. In the first Se2- site, Se2- is bonded to three equivalent Mg2+ and two equivalent Er3+ atoms to form a mixture of edge and corner-sharing SeEr2Mg3 square pyramids. In the second Se2- site, Se2- is bonded in a rectangular see-saw-like geometry to four Er3+ atoms. In the third Se2- site, Se2- is bonded in a distorted T-shaped geometry to three Er3+ atoms. In the fourth Se2- site, Se2- is bonded to two equivalent Mg2+ and three Er3+ atoms to form SeEr3Mg2 square pyramids that share corners with two equivalent SeEr2Mg3 square pyramids and edges with five SeEr3Mg2 square pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Er2MgSe4 by Materials Project

MgEr2Se4 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 ErSe6 octahedra, corners with two equivalent MgSe6 octahedra, corners with four ErSe7 pentagonal bipyramids, an edgeedge with one MgSe6 octahedra, edges with four ErSe6 octahedra, and edges with three ErSe7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 13–54°. There are a spread of Mg–Se bond distances ranging from 2.66–2.96 Å. In the second Mg2+ site, Mg2+ is bonded to six Se2- atoms to form MgSe6 octahedra that share a cornercorner with one ErSe6 octahedra, corners with two equivalent MgSe6 octahedra, corners with four ErSe7 pentagonal bipyramids, an edgeedge with one MgSe6 octahedra, edges with four ErSe6 octahedra, and edges with three ErSe7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 13–54°. There are a spread of Mg–Se bond distances ranging from 2.70–2.87 Å. There are four inequivalent Er3+ sites. In the first Er3+ site, Er3+ is bonded to six Se2- atoms to form ErSe6 octahedra that share a cornercorner with one MgSe6 octahedra, corners with two equivalent ErSe6 octahedra, corners with four ErSe7 pentagonal bipyramids, an edgeedge with one ErSe6 octahedra, edges with four MgSe6 octahedra, and edges with three ErSe7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 12–54°. There are a spread of Er–Se bond distances ranging from 2.80–2.87 Å. In the second Er3+ site, Er3+ is bonded to six Se2- atoms to form ErSe6 octahedra that share a cornercorner with one MgSe6 octahedra, corners with two equivalent ErSe6 octahedra, corners with four ErSe7 pentagonal bipyramids, an edgeedge with one ErSe6 octahedra, edges with four MgSe6 octahedra, and edges with three ErSe7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 12–54°. There are a spread of Er–Se bond distances ranging from 2.79–2.90 Å. In the third Er3+ site, Er3+ is bonded to seven Se2- atoms to form distorted ErSe7 pentagonal bipyramids that share corners with four MgSe6 octahedra, corners with four ErSe6 octahedra, edges with three MgSe6 octahedra, edges with three ErSe6 octahedra, and faces with two equivalent ErSe7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 16–69°. There are a spread of Er–Se bond distances ranging from 2.84–3.13 Å. In the fourth Er3+ site, Er3+ is bonded to seven Se2- atoms to form distorted ErSe7 pentagonal bipyramids that share corners with four MgSe6 octahedra, corners with four ErSe6 octahedra, edges with three MgSe6 octahedra, edges with three ErSe6 octahedra, and faces with two equivalent ErSe7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 17–67°. There are a spread of Er–Se bond distances ranging from 2.83–3.15 Å. There are eight inequivalent Se2- sites. In the first Se2- site, Se2- is bonded to two Mg2+ and three Er3+ atoms to form distorted SeEr3Mg2 trigonal bipyramids that share corners with two equivalent SeEr3Mg2 square pyramids, corners with three equivalent SeEr3Mg tetrahedra, corners with two equivalent SeEr3Mg2 trigonal bipyramids, edges with five SeEr3Mg2 square pyramids, and edges with three SeEr3Mg2 trigonal bipyramids. In the second Se2- site, Se2- is bonded to two Mg2+ and three Er3+ atoms to form distorted SeEr3Mg2 trigonal bipyramids that share corners with six SeEr3Mg2 square pyramids, corners with two equivalent SeEr3Mg tetrahedra, corners with two equivalent SeEr3Mg2 trigonal bipyramids, edges with three SeEr3Mg2 square pyramids, an edgeedge with one SeEr3Mg tetrahedra, and edges with three SeEr3Mg2 trigonal bipyramids. In the third Se2- site, Se2- is bonded to one Mg2+ and three Er3+ atoms to form a mixture of distorted edge and corner-sharing SeEr3Mg tetrahedra. In the fourth Se2- site, Se2- is bonded in a distorted rectangular see-saw-like geometry to one Mg2+ and three Er3+ atoms. In the fifth Se2- site, Se2- is bonded to two Mg2+ and three Er3+ atoms to form distorted SeEr3Mg2 square pyramids that share a cornercorner with one SeEr3Mg tetrahedra, corners with eight SeEr3Mg2 trigonal bipyramids, edges with four SeEr3Mg2 square pyramids, an edgeedge with one SeEr3Mg tetrahedra, and edges with two SeEr3Mg2 trigonal bipyramids. In the sixth Se2- site, Se2- is bonded to two Mg2+ and three Er3+ atoms to form distorted SeEr3Mg2 square pyramids that share corners with two equivalent SeEr4Mg square pyramids, a cornercorner with one SeEr3Mg tetrahedra, corners with six SeEr3Mg2 trigonal bipyramids, edges with three SeEr3Mg2 square pyramids, an edgeedge with one SeEr3Mg tetrahedra, and edges with three SeEr3Mg2 trigonal bipyramids. In the seventh Se2- site, Se2- is bonded to one Mg2+ and four Er3+ atoms to form distorted SeEr4Mg square pyramids that share corners with two equivalent SeEr3Mg2 square pyramids, corners with two equivalent SeEr3Mg tetrahedra, corners with two equivalent SeEr4Mg trigonal bipyramids, edges with three SeEr3Mg2 square pyramids, an edgeedge with one SeEr3Mg tetrahedra, and edges with five SeEr3Mg2 trigonal bipyramids. In the eighth Se2- site, Se2- is bonded to one Mg2+ and four Er3+ atoms to form distorted SeEr4Mg trigonal bipyramids that share corners with eight SeEr3Mg2 square pyramids, corners with three equivalent SeEr3Mg tetrahedra, edges with two SeEr3Mg2 square pyramids, and edges with four SeEr3Mg2 trigonal bipyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Er2MgSe4 by Materials Project

MgEr2Se4 crystallizes in the tetragonal I-42d space group. The structure is three-dimensional. Mg2+ is bonded in a 4-coordinate geometry to eight equivalent Se2- atoms. There are four shorter (2.73 Å) and four longer (3.29 Å) Mg–Se bond lengths. Er3+ is bonded in a 8-coordinate geometry to eight equivalent Se2- atoms. There are a spread of Er–Se bond distances ranging from 2.80–3.26 Å. Se2- is bonded in a 6-coordinate geometry to two equivalent Mg2+ and four equivalent Er3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Er2MgSe4 by Materials Project

MgEr2Se4 is Spinel structured and crystallizes in the cubic Fd-3m space group. The structure is three-dimensional. Mg2+ is bonded to four equivalent Se2- atoms to form MgSe4 tetrahedra that share corners with twelve equivalent ErSe6 octahedra. The corner-sharing octahedral tilt angles are 56°. All Mg–Se bond lengths are 2.62 Å. Er3+ is bonded to six equivalent Se2- atoms to form ErSe6 octahedra that share corners with six equivalent MgSe4 tetrahedra and edges with six equivalent ErSe6 octahedra. All Er–Se bond lengths are 2.85 Å. Se2- is bonded in a distorted rectangular see-saw-like geometry to one Mg2+ and three equivalent Er3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Er2MgSe4 by Materials Project

MgEr2Se4 crystallizes in the triclinic P-1 space group. The structure is two-dimensional and consists of one MgEr2Se4 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 ErSe6 octahedra, and corners with six ErSe4 tetrahedra. The corner-sharing octahedra tilt angles range from 59–60°. 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 ErSe4 tetrahedra, edges with two equivalent MgSe6 octahedra, and edges with four equivalent ErSe6 octahedra. There are a spread of Mg–Se bond distances ranging from 2.80–2.85 Å. There are four inequivalent Er3+ sites. In the first Er3+ site, Er3+ is bonded to four Se2- atoms to form ErSe4 tetrahedra that share a cornercorner with one ErSe6 octahedra, corners with two equivalent MgSe6 octahedra, corners with two equivalent MgSe4 tetrahedra, and corners with four ErSe4 tetrahedra. The corner-sharing octahedra tilt angles range from 58–62°. There are a spread of Er–Se bond distances ranging from 2.68–2.72 Å. In the second Er3+ site, Er3+ is bonded to six Se2- atoms to form ErSe6 octahedra that share corners with two equivalent MgSe4 tetrahedra, corners with four ErSe4 tetrahedra, edges with two equivalent ErSe6 octahedra, and edges with four equivalent MgSe6 octahedra. There are a spread of Er–Se bond distances ranging from 2.85–2.92 Å. In the third Er3+ site, Er3+ is bonded to four Se2- atoms to form ErSe4 tetrahedra that share a cornercorner with one ErSe6 octahedra, corners with two equivalent MgSe6 octahedra, corners with two equivalent MgSe4 tetrahedra, and corners with four ErSe4 tetrahedra. The corner-sharing octahedra tilt angles range from 58–63°. There are a spread of Er–Se bond distances ranging from 2.68–2.72 Å. In the fourth Er3+ site, Er3+ is bonded to four Se2- atoms to form ErSe4 tetrahedra that share a cornercorner with one MgSe6 octahedra, corners with two equivalent ErSe6 octahedra, corners with two equivalent MgSe4 tetrahedra, and corners with four ErSe4 tetrahedra. The corner-sharing octahedra tilt angles range from 58–62°. There are a spread of Er–Se bond distances ranging from 2.69–2.72 Å. There are eight inequivalent Se2- sites. In the first Se2- site, Se2- is bonded to two equivalent Mg2+ and two Er3+ atoms to form distorted SeEr2Mg2 tetrahedra that share corners with seven SeEr3Mg tetrahedra, corners with two equivalent SeEr2Mg2 trigonal pyramids, edges with two SeEr2Mg2 tetrahedra, and an edgeedge with one SeEr2Mg2 trigonal pyramid. In the second Se2- site, Se2- is bonded to two Mg2+ and two equivalent Er3+ atoms to form distorted SeEr2Mg2 trigonal pyramids that share corners with nine SeEr2Mg2 tetrahedra, edges with two SeEr3Mg tetrahedra, and an edgeedge with one SeEr2Mg2 trigonal pyramid. In the third Se2- site, Se2- is bonded in a trigonal non-coplanar geometry to one Mg2+ and two Er3+ atoms. In the fourth Se2- site, Se2- is bonded in a trigonal non-coplanar geometry to three Er3+ atoms. In the fifth Se2- site, Se2- is bonded in a trigonal non-coplanar geometry to one Mg2+ and two Er3+ atoms. In the sixth Se2- site, Se2- is bonded in a trigonal non-coplanar geometry to one Mg2+ and two Er3+ atoms. In the seventh Se2- site, Se2- is bonded to one Mg2+ and three Er3+ atoms to form distorted SeEr3Mg tetrahedra that share corners with six SeEr2Mg2 tetrahedra, corners with three equivalent SeEr2Mg2 trigonal pyramids, edges with two SeEr3Mg tetrahedra, and an edgeedge with one SeEr2Mg2 trigonal pyramid. In the eighth Se2- site, Se2- is bonded to two equivalent Mg2+ and two Er3+ atoms to form distorted SeEr2Mg2 tetrahedra that share corners with five SeEr2Mg2 tetrahedra, corners with four equivalent SeEr2Mg2 trigonal pyramids, and edges with three SeEr3Mg tetrahedra.

36 MATERIALS SCIENCE↗