DOE OSTI2020
Na2GeF6 is zeta iron carbide-derived structured and crystallizes in the trigonal P321 space group. The structure is three-dimensional. there are two inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded to six F1- atoms to form NaF6 octahedra that share corners with four equivalent GeF6 octahedra, corners with six equivalent NaF6 octahedra, and an edgeedge with one GeF6 octahedra. The corner-sharing octahedra tilt angles range from 44–62°. There are a spread of Na–F bond distances ranging from 2.34–2.46 Å. In the second Na1+ site, Na1+ is bonded to six F1- atoms to form distorted NaF6 octahedra that share corners with two equivalent GeF6 octahedra, corners with six equivalent NaF6 octahedra, and edges with two equivalent GeF6 octahedra. The corner-sharing octahedra tilt angles range from 48–62°. There are a spread of Na–F bond distances ranging from 2.25–2.37 Å. There are two inequivalent Ge4+ sites. In the first Ge4+ site, Ge4+ is bonded to six F1- atoms to form GeF6 octahedra that share corners with six equivalent NaF6 octahedra and edges with three equivalent NaF6 octahedra. The corner-sharing octahedra tilt angles range from 44–45°. All Ge–F bond lengths are 1.84 Å. In the second Ge4+ site, Ge4+ is bonded to six equivalent F1- atoms to form GeF6 octahedra that share corners with six equivalent NaF6 octahedra and edges with three equivalent NaF6 octahedra. The corner-sharing octahedral tilt angles are 48°. All Ge–F bond lengths are 1.83 Å. There are three inequivalent F1- sites. In the first F1- site, F1- is bonded in a distorted trigonal planar geometry to two Na1+ and one Ge4+ atom. In the second F1- site, F1- is bonded in a distorted trigonal planar geometry to two Na1+ and one Ge4+ atom. In the third F1- site, F1- is bonded in a distorted trigonal planar geometry to two Na1+ and one Ge4+ atom.