Materials Data on Na2MgVF7 by Materials Project

Abstract

Na2MgVF7 crystallizes in the orthorhombic Imm2 space group. The structure is three-dimensional. there are two inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded to eight F1- atoms to form distorted NaF8 hexagonal bipyramids that share corners with two equivalent NaF8 hexagonal bipyramids, corners with two equivalent VF6 octahedra, edges with two equivalent VF6 octahedra, and edges with four equivalent MgF6 octahedra. The corner-sharing octahedral tilt angles are 55°. There are a spread of Na–F bond distances ranging from 2.26–2.90 Å. In the second Na1+ site, Na1+ is bonded in a distorted body-centered cubic geometry to eight F1- atoms. There are four shorter (2.46 Å) and four longer (2.79 Å) Na–F bond lengths. Mg2+ is bonded to six F1- atoms to form MgF6 octahedra that share corners with two equivalent MgF6 octahedra, corners with four equivalent VF6 octahedra, and edges with four equivalent NaF8 hexagonal bipyramids. The corner-sharing octahedra tilt angles range from 41–42°. There are a spread of Mg–F bond distances ranging from 1.95–2.01 Å. V3+ is bonded to six F1- atoms to form VF6 octahedra that share corners with two equivalent NaF8 hexagonal bipyramids, corners with four equivalent MgF6 octahedra, and edges with two equivalent NaF8 hexagonal bipyramids. The corner-sharing octahedral tilt angles are 42°. There are a spread of V–F bond distances ranging from 1.96–2.00 Å. There are six inequivalent F1- sites. In the first F1- site, F1- is bonded to three Na1+ and one V3+ atom to form a mixture of distorted edge and corner-sharing FNa3V tetrahedra. In the second F1- site, F1- is bonded in a 4-coordinate geometry to two Na1+, one Mg2+, and one V3+ atom. In the third F1- site, F1- is bonded in a 4-coordinate geometry to two Na1+, one Mg2+, and one V3+ atom. In the fourth F1- site, F1- is bonded in a distorted bent 150 degrees geometry to two equivalent Na1+ and two equivalent Mg2+ atoms. In the fifth F1- site, F1- is bonded to three Na1+ and one V3+ atom to form a mixture of distorted edge and corner-sharing FNa3V tetrahedra. In the sixth F1- site, F1- is bonded in a distorted bent 150 degrees geometry to two equivalent Na1+ and two equivalent Mg2+ atoms.