Materials Data on Er6Mg(GeS7)2 by Materials Project
MgEr6(GeS7)2 crystallizes in the trigonal P3 space group. The structure is three-dimensional. Mg2+ is bonded in an octahedral geometry to six S2- atoms. There are three shorter (2.55 Å) and three longer (2.59 Å) Mg–S bond lengths. There are two inequivalent Er3+ sites. In the first Er3+ site, Er3+ is bonded in a 7-coordinate geometry to seven S2- atoms. There are a spread of Er–S bond distances ranging from 2.71–3.03 Å. In the second Er3+ site, Er3+ is bonded in a 7-coordinate geometry to seven S2- atoms. There are a spread of Er–S bond distances ranging from 2.69–3.01 Å. There are two inequivalent Ge4+ sites. In the first Ge4+ site, Ge4+ is bonded in a tetrahedral geometry to four S2- atoms. There are one shorter (2.21 Å) and three longer (2.24 Å) Ge–S bond lengths. In the second Ge4+ site, Ge4+ is bonded in a tetrahedral geometry to four S2- atoms. There are one shorter (2.22 Å) and three longer (2.24 Å) Ge–S bond lengths. There are six inequivalent S2- sites. In the first S2- site, S2- is bonded in a 4-coordinate geometry to one Mg2+ and three Er3+ atoms. In the second S2- site, S2- is bonded to one Mg2+ and three Er3+ atoms to form distorted SEr3Mg trigonal pyramids that share corners with three SEr3Ge tetrahedra and edges with two equivalent SEr3Mg trigonal pyramids. In the third S2- site, S2- is bonded to three equivalent Er3+ and one Ge4+ atom to form corner-sharing SEr3Ge tetrahedra. In the fourth S2- site, S2- is bonded to three equivalent Er3+ and one Ge4+ atom to form corner-sharing SEr3Ge tetrahedra. In the fifth S2- site, S2- is bonded in a distorted rectangular see-saw-like geometry to three Er3+ and one Ge4+ atom. In the sixth S2- site, S2- is bonded in a distorted rectangular see-saw-like geometry to three Er3+ and one Ge4+ atom.