Materials Data on Nd2MgSe4 by Materials Project

MgNd2Se4 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 NdSe6 octahedra and edges with three NdSe6 octahedra. The corner-sharing octahedra tilt angles range from 59–64°. There are a spread of Mg–Se bond distances ranging from 2.55–2.62 Å. There are two inequivalent Nd3+ sites. In the first Nd3+ site, Nd3+ is bonded to six Se2- atoms to form NdSe6 octahedra that share corners with four equivalent NdSe6 octahedra, corners with two equivalent MgSe4 tetrahedra, edges with four NdSe6 octahedra, and edges with two equivalent MgSe4 tetrahedra. The corner-sharing octahedra tilt angles range from 51–56°. There are a spread of Nd–Se bond distances ranging from 2.95–3.01 Å. In the second Nd3+ site, Nd3+ is bonded to six Se2- atoms to form NdSe6 octahedra that share corners with eight NdSe6 octahedra, corners with four equivalent MgSe4 tetrahedra, edges with two equivalent NdSe6 octahedra, and an edgeedge with one MgSe4 tetrahedra. The corner-sharing octahedra tilt angles range from 47–56°. There are a spread of Nd–Se bond distances ranging from 2.94–3.02 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 Nd3+ atoms. In the second Se2- site, Se2- is bonded in a rectangular see-saw-like geometry to one Mg2+ and three Nd3+ atoms. In the third Se2- site, Se2- is bonded to one Mg2+ and three Nd3+ atoms to form distorted corner-sharing SeNd3Mg trigonal pyramids.