Materials Data on NaTaGeO5 by Materials Project

Abstract

NaTaGeO5 crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. Na1+ is bonded to seven O2- atoms to form distorted NaO7 pentagonal bipyramids that share corners with four equivalent GeO4 tetrahedra, edges with four equivalent TaO6 octahedra, edges with two equivalent NaO7 pentagonal bipyramids, and an edgeedge with one GeO4 tetrahedra. There are a spread of Na–O bond distances ranging from 2.34–2.69 Å. Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with two equivalent TaO6 octahedra, corners with four equivalent GeO4 tetrahedra, and edges with four equivalent NaO7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 34°. There are a spread of Ta–O bond distances ranging from 1.96–2.03 Å. Ge4+ is bonded to four O2- atoms to form GeO4 tetrahedra that share corners with four equivalent TaO6 octahedra, corners with four equivalent NaO7 pentagonal bipyramids, and an edgeedge with one NaO7 pentagonal bipyramid. The corner-sharing octahedra tilt angles range from 36–51°. There is two shorter (1.76 Å) and two longer (1.77 Å) Ge–O bond length. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+ and two equivalent Ta5+ atoms. In the second O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Na1+, one Ta5+, and one Ge4+ atom. In the third O2- site, O2- is bonded in a 3-coordinate geometry to one Na1+, one Ta5+, and one Ge4+ atom.