DOI: 10.17188/1663427
title: Materials Data on Mg6NbCuO8 by Materials Project

description: Mg6NbCuO8 is alpha Po-derived structured and crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. there are three inequivalent Mg2+ sites. In the first Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with two equivalent CuO6 octahedra, corners with four equivalent MgO6 octahedra, and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are two shorter (2.07 Å) and four longer (2.15 Å) Mg–O bond lengths. In the second Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with two equivalent NbO6 octahedra, corners with four equivalent MgO6 octahedra, and edges with twelve MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. All Mg–O bond lengths are 2.15 Å. In the third Mg2+ site, Mg2+ is bonded to six O2- atoms to form MgO6 octahedra that share corners with six equivalent MgO6 octahedra, edges with two equivalent NbO6 octahedra, edges with two equivalent CuO6 octahedra, and edges with eight MgO6 octahedra. The corner-sharing octahedra tilt angles range from 0–4°. There are five shorter (2.15 Å) and one longer (2.27 Å) Mg–O bond lengths. Nb3+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with two equivalent MgO6 octahedra, corners with four equivalent NbO6 octahedra, edges with four equivalent CuO6 octahedra, and edges with eight equivalent MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are four shorter (2.15 Å) and two longer (2.27 Å) Nb–O bond lengths. Cu1+ is bonded to six O2- atoms to form CuO6 octahedra that share corners with two equivalent MgO6 octahedra, corners with four equivalent CuO6 octahedra, edges with four equivalent NbO6 octahedra, and edges with eight equivalent MgO6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are four shorter (2.15 Å) and two longer (2.35 Å) Cu–O bond lengths. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded to five Mg2+ and one Cu1+ atom to form OMg5Cu octahedra that share corners with six equivalent OMg5Cu octahedra and edges with twelve OMg5Nb octahedra. The corner-sharing octahedra tilt angles range from 0–4°. In the second O2- site, O2- is bonded to five Mg2+ and one Nb3+ atom to form OMg5Nb octahedra that share corners with six equivalent OMg5Nb octahedra and edges with twelve OMg5Cu octahedra. The corner-sharing octahedral tilt angles are 0°. In the third O2- site, O2- is bonded to two equivalent Mg2+, two equivalent Nb3+, and two equivalent Cu1+ atoms to form OMg2Nb2Cu2 octahedra that share corners with six OMg2Nb2Cu2 octahedra and edges with twelve OMg5Cu octahedra. The corner-sharing octahedral tilt angles are 0°. In the fourth O2- site, O2- is bonded to six Mg2+ atoms to form OMg6 octahedra that share corners with six OMg2Nb2Cu2 octahedra and edges with twelve OMg5Cu octahedra. The corner-sharing octahedral tilt angles are 0°. In the fifth O2- site, O2- is bonded to two equivalent Mg2+, two equivalent Nb3+, and two equivalent Cu1+ atoms to form OMg2Nb2Cu2 octahedra that share corners with six OMg2Nb2Cu2 octahedra and edges with twelve OMg5Cu octahedra. The corner-sharing octahedral tilt angles are 0°. Both O–Mg bond lengths are 2.27 Å. In the sixth O2- site, O2- is bonded to six Mg2+ atoms to form OMg6 octahedra that share corners with six OMg2Nb2Cu2 octahedra and edges with twelve OMg5Cu octahedra. The corner-sharing octahedral tilt angles are 0°. Both O–Mg bond lengths are 2.15 Å.