Materials Data on RbMgAlF6 by Materials Project
RbMgAlF6 crystallizes in the orthorhombic Imma space group. The structure is three-dimensional. Rb1+ is bonded to six F1- atoms to form distorted RbF6 octahedra that share corners with six equivalent MgF6 octahedra and corners with six equivalent AlF6 octahedra. The corner-sharing octahedra tilt angles range from 66–73°. There are a spread of Rb–F bond distances ranging from 2.91–3.32 Å. Mg2+ is bonded to six F1- atoms to form MgF6 octahedra that share corners with two equivalent MgF6 octahedra, corners with four equivalent AlF6 octahedra, and corners with six equivalent RbF6 octahedra. The corner-sharing octahedra tilt angles range from 42–73°. There are two shorter (1.98 Å) and four longer (2.02 Å) Mg–F bond lengths. Al3+ is bonded to six F1- atoms to form AlF6 octahedra that share corners with two equivalent AlF6 octahedra, corners with four equivalent MgF6 octahedra, and corners with six equivalent RbF6 octahedra. The corner-sharing octahedra tilt angles range from 33–73°. There is four shorter (1.81 Å) and two longer (1.86 Å) Al–F bond length. There are three inequivalent F1- sites. In the first F1- site, F1- is bonded in a bent 150 degrees geometry to one Rb1+ and two equivalent Al3+ atoms. In the second F1- site, F1- is bonded in a distorted trigonal planar geometry to one Rb1+ and two equivalent Mg2+ atoms. In the third F1- site, F1- is bonded in a 2-coordinate geometry to one Rb1+, one Mg2+, and one Al3+ atom.