DOI: 10.17188/1704142
title: Materials Data on Nd2MgSe4 by Materials Project

description: MgNd2Se4 crystallizes in the triclinic P-1 space group. The structure is two-dimensional and consists of one MgNd2Se4 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 NdSe6 octahedra, and corners with six NdSe4 tetrahedra. 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. 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 NdSe4 tetrahedra, edges with two equivalent MgSe6 octahedra, and edges with four equivalent NdSe6 octahedra. There are a spread of Mg–Se bond distances ranging from 2.82–2.93 Å. There are four inequivalent Nd3+ sites. In the first Nd3+ site, Nd3+ is bonded to four Se2- atoms to form NdSe4 tetrahedra that share a cornercorner with one NdSe6 octahedra, corners with two equivalent MgSe6 octahedra, corners with two equivalent MgSe4 tetrahedra, and corners with four NdSe4 tetrahedra. The corner-sharing octahedra tilt angles range from 58–64°. There are a spread of Nd–Se bond distances ranging from 2.79–2.83 Å. In the second Nd3+ site, Nd3+ is bonded to six Se2- atoms to form NdSe6 octahedra that share corners with two equivalent MgSe4 tetrahedra, corners with four NdSe4 tetrahedra, edges with two equivalent NdSe6 octahedra, and edges with four equivalent MgSe6 octahedra. There are a spread of Nd–Se bond distances ranging from 2.99–3.04 Å. In the third Nd3+ site, Nd3+ is bonded to four Se2- atoms to form NdSe4 tetrahedra that share a cornercorner with one NdSe6 octahedra, corners with two equivalent MgSe6 octahedra, corners with two equivalent MgSe4 tetrahedra, and corners with four NdSe4 tetrahedra. The corner-sharing octahedra tilt angles range from 58–67°. There are a spread of Nd–Se bond distances ranging from 2.79–2.82 Å. In the fourth Nd3+ site, Nd3+ is bonded to four Se2- atoms to form NdSe4 tetrahedra that share a cornercorner with one MgSe6 octahedra, corners with two equivalent NdSe6 octahedra, corners with two equivalent MgSe4 tetrahedra, and corners with four NdSe4 tetrahedra. The corner-sharing octahedra tilt angles range from 56–65°. There are one shorter (2.79 Å) and three longer (2.81 Å) Nd–Se bond lengths. There are eight inequivalent Se2- sites. In the first Se2- site, Se2- is bonded to two equivalent Mg2+ and two Nd3+ atoms to form a mixture of distorted edge and corner-sharing SeNd2Mg2 tetrahedra. In the second Se2- site, Se2- is bonded to two Mg2+ and two equivalent Nd3+ atoms to form distorted SeNd2Mg2 tetrahedra that share corners with nine SeNd2Mg2 tetrahedra and edges with three SeNd3Mg tetrahedra. In the third Se2- site, Se2- is bonded in a trigonal non-coplanar geometry to one Mg2+ and two Nd3+ atoms. In the fourth Se2- site, Se2- is bonded in a trigonal non-coplanar geometry to three Nd3+ atoms. In the fifth Se2- site, Se2- is bonded in a trigonal non-coplanar geometry to one Mg2+ and two Nd3+ atoms. In the sixth Se2- site, Se2- is bonded in a trigonal non-coplanar geometry to one Mg2+ and two Nd3+ atoms. In the seventh Se2- site, Se2- is bonded to one Mg2+ and three Nd3+ atoms to form distorted SeNd3Mg tetrahedra that share corners with nine SeNd2Mg2 tetrahedra and edges with three SeNd3Mg tetrahedra. In the eighth Se2- site, Se2- is bonded to two equivalent Mg2+ and two Nd3+ atoms to form distorted SeNd2Mg2 tetrahedra that share corners with nine SeNd2Mg2 tetrahedra and edges with three SeNd3Mg tetrahedra.