DOI: 10.17188/1740592
title: Materials Data on Nd2MgSe4 by Materials Project

description: MgNd2Se4 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 NdSe6 octahedra, corners with two equivalent MgSe6 octahedra, corners with four NdSe7 pentagonal bipyramids, an edgeedge with one MgSe6 octahedra, edges with four NdSe6 octahedra, and edges with three NdSe7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 11–53°. There are a spread of Mg–Se bond distances ranging from 2.66–3.12 Å. In the second Mg2+ site, Mg2+ is bonded to six Se2- atoms to form MgSe6 octahedra that share a cornercorner with one NdSe6 octahedra, corners with two equivalent MgSe6 octahedra, corners with four NdSe7 pentagonal bipyramids, an edgeedge with one MgSe6 octahedra, edges with four NdSe6 octahedra, and edges with three NdSe7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 11–53°. There are a spread of Mg–Se bond distances ranging from 2.67–3.00 Å. There are four inequivalent Nd3+ sites. In the first Nd3+ site, Nd3+ is bonded to six Se2- atoms to form NdSe6 octahedra that share a cornercorner with one MgSe6 octahedra, corners with two equivalent NdSe6 octahedra, corners with four NdSe7 pentagonal bipyramids, an edgeedge with one NdSe6 octahedra, edges with four MgSe6 octahedra, and edges with three NdSe7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 11–53°. There are a spread of Nd–Se bond distances ranging from 2.90–2.97 Å. In the second Nd3+ site, Nd3+ is bonded to six Se2- atoms to form NdSe6 octahedra that share a cornercorner with one MgSe6 octahedra, corners with two equivalent NdSe6 octahedra, corners with four NdSe7 pentagonal bipyramids, an edgeedge with one NdSe6 octahedra, edges with four MgSe6 octahedra, and edges with three NdSe7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 11–53°. There are a spread of Nd–Se bond distances ranging from 2.89–3.01 Å. In the third Nd3+ site, Nd3+ is bonded to seven Se2- atoms to form distorted NdSe7 pentagonal bipyramids that share corners with four MgSe6 octahedra, corners with four NdSe6 octahedra, edges with three MgSe6 octahedra, edges with three NdSe6 octahedra, and faces with two equivalent NdSe7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 14–71°. There are a spread of Nd–Se bond distances ranging from 2.95–3.23 Å. In the fourth Nd3+ site, Nd3+ is bonded to seven Se2- atoms to form distorted NdSe7 pentagonal bipyramids that share corners with four MgSe6 octahedra, corners with four NdSe6 octahedra, edges with three MgSe6 octahedra, edges with three NdSe6 octahedra, and faces with two equivalent NdSe7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 16–71°. There are a spread of Nd–Se bond distances ranging from 2.94–3.28 Å. There are eight inequivalent Se2- sites. In the first Se2- site, Se2- is bonded to two Mg2+ and three Nd3+ atoms to form distorted SeNd3Mg2 trigonal bipyramids that share corners with two equivalent SeNd3Mg2 square pyramids, corners with three equivalent SeNd3Mg tetrahedra, corners with two equivalent SeNd3Mg2 trigonal bipyramids, edges with five SeNd3Mg2 square pyramids, and edges with three SeNd3Mg2 trigonal bipyramids. In the second Se2- site, Se2- is bonded to two Mg2+ and three Nd3+ atoms to form distorted SeNd3Mg2 trigonal bipyramids that share corners with six SeNd3Mg2 square pyramids, corners with two equivalent SeNd3Mg tetrahedra, corners with two equivalent SeNd3Mg2 trigonal bipyramids, edges with three SeNd3Mg2 square pyramids, an edgeedge with one SeNd3Mg tetrahedra, and edges with three SeNd3Mg2 trigonal bipyramids. In the third Se2- site, Se2- is bonded to one Mg2+ and three Nd3+ atoms to form a mixture of distorted corner and edge-sharing SeNd3Mg tetrahedra. In the fourth Se2- site, Se2- is bonded in a distorted rectangular see-saw-like geometry to one Mg2+ and three Nd3+ atoms. In the fifth Se2- site, Se2- is bonded to two Mg2+ and three Nd3+ atoms to form distorted SeNd3Mg2 square pyramids that share a cornercorner with one SeNd3Mg tetrahedra, corners with eight SeNd3Mg2 trigonal bipyramids, edges with four SeNd3Mg2 square pyramids, an edgeedge with one SeNd3Mg tetrahedra, and edges with two SeNd3Mg2 trigonal bipyramids. In the sixth Se2- site, Se2- is bonded to two Mg2+ and three Nd3+ atoms to form SeNd3Mg2 square pyramids that share corners with two equivalent SeNd4Mg square pyramids, a cornercorner with one SeNd3Mg tetrahedra, corners with six SeNd3Mg2 trigonal bipyramids, edges with three SeNd3Mg2 square pyramids, an edgeedge with one SeNd3Mg tetrahedra, and edges with three SeNd3Mg2 trigonal bipyramids. In the seventh Se2- site, Se2- is bonded to one Mg2+ and four Nd3+ atoms to form distorted SeNd4Mg square pyramids that share corners with two equivalent SeNd3Mg2 square pyramids, corners with two equivalent SeNd3Mg tetrahedra, corners with two equivalent SeNd4Mg trigonal bipyramids, edges with three SeNd3Mg2 square pyramids, an edgeedge with one SeNd3Mg tetrahedra, and edges with five SeNd3Mg2 trigonal bipyramids. In the eighth Se2- site, Se2- is bonded to one Mg2+ and four Nd3+ atoms to form distorted SeNd4Mg trigonal bipyramids that share corners with eight SeNd3Mg2 square pyramids, corners with three equivalent SeNd3Mg tetrahedra, edges with two SeNd3Mg2 square pyramids, and edges with four SeNd3Mg2 trigonal bipyramids.