Materials Data on Tb2MgSe4 by Materials Project

MgTb2Se4 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 TbSe6 octahedra and edges with three TbSe6 octahedra. The corner-sharing octahedra tilt angles range from 59–66°. There are a spread of Mg–Se bond distances ranging from 2.54–2.62 Å. There are two inequivalent Tb3+ sites. In the first Tb3+ site, Tb3+ is bonded to six Se2- atoms to form TbSe6 octahedra that share corners with four equivalent TbSe6 octahedra, corners with two equivalent MgSe4 tetrahedra, edges with four TbSe6 octahedra, and edges with two equivalent MgSe4 tetrahedra. The corner-sharing octahedra tilt angles range from 50–54°. There are a spread of Tb–Se bond distances ranging from 2.85–2.92 Å. In the second Tb3+ site, Tb3+ is bonded to six Se2- atoms to form TbSe6 octahedra that share corners with eight TbSe6 octahedra, corners with four equivalent MgSe4 tetrahedra, edges with two equivalent TbSe6 octahedra, and an edgeedge with one MgSe4 tetrahedra. The corner-sharing octahedra tilt angles range from 46–54°. There are a spread of Tb–Se bond distances ranging from 2.86–2.94 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 Tb3+ atoms. In the second Se2- site, Se2- is bonded in a rectangular see-saw-like geometry to one Mg2+ and three Tb3+ atoms. In the third Se2- site, Se2- is bonded to one Mg2+ and three Tb3+ atoms to form distorted corner-sharing SeTb3Mg trigonal pyramids.