Materials Data on Na4Hf2(GeO4)3 by Materials Project
Na4Hf2(GeO4)3 crystallizes in the trigonal R-3c space group. The structure is three-dimensional. there are two inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded in a 6-coordinate geometry to six equivalent O2- atoms. All Na–O bond lengths are 2.47 Å. In the second Na1+ site, Na1+ is bonded in a distorted hexagonal planar geometry to six O2- atoms. There are a spread of Na–O bond distances ranging from 2.55–2.63 Å. Hf4+ is bonded to six O2- atoms to form HfO6 octahedra that share corners with six equivalent GeO4 tetrahedra. There are three shorter (2.03 Å) and three longer (2.13 Å) Hf–O bond lengths. Ge4+ is bonded to four O2- atoms to form GeO4 tetrahedra that share corners with four equivalent HfO6 octahedra. The corner-sharing octahedra tilt angles range from 28–41°. There is two shorter (1.76 Å) and two longer (1.77 Å) Ge–O bond length. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to three Na1+, one Hf4+, and one Ge4+ atom to form a mixture of distorted corner, edge, and face-sharing ONa3HfGe trigonal bipyramids. In the second O2- site, O2- is bonded in a 2-coordinate geometry to one Na1+, one Hf4+, and one Ge4+ atom.