Materials Data on Na2CaSn2(GeO4)3 by Materials Project

Abstract

Na2CaSn2Ge3O12 crystallizes in the tetragonal I4_1/acd space group. The structure is three-dimensional. Na1+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are a spread of Na–O bond distances ranging from 2.46–2.60 Å. Ca2+ is bonded in a distorted body-centered cubic geometry to eight O2- atoms. There are four shorter (2.41 Å) and four longer (2.55 Å) Ca–O bond lengths. Sn4+ is bonded to six O2- atoms to form SnO6 octahedra that share corners with six GeO4 tetrahedra. There are a spread of Sn–O bond distances ranging from 2.07–2.10 Å. There are two inequivalent Ge4+ sites. In the first Ge4+ site, Ge4+ is bonded to four O2- atoms to form GeO4 tetrahedra that share corners with four equivalent SnO6 octahedra. The corner-sharing octahedra tilt angles range from 48–50°. There is two shorter (1.78 Å) and two longer (1.80 Å) Ge–O bond length. In the second Ge4+ site, Ge4+ is bonded to four equivalent O2- atoms to form GeO4 tetrahedra that share corners with four equivalent SnO6 octahedra. The corner-sharing octahedral tilt angles are 49°. All Ge–O bond lengths are 1.78 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Na1+, one Sn4+, and one Ge4+ atom. In the second O2- site, O2- is bonded in a 4-coordinate geometry to one Na1+, one Ca2+, one Sn4+, and one Ge4+ atom. In the third O2- site, O2- is bonded in a 4-coordinate geometry to one Na1+, one Ca2+, one Sn4+, and one Ge4+ atom.