DOE OSTI2020
Ca3Te2(ZnO4)3 is Ilmenite-derived structured and crystallizes in the cubic I4_132 space group. The structure is three-dimensional. Ca2+ is bonded to six O2- atoms to form distorted CaO6 pentagonal pyramids that share corners with two equivalent TeO6 octahedra, edges with two equivalent TeO6 octahedra, edges with two equivalent CaO6 pentagonal pyramids, and edges with four equivalent ZnO6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 24°. There are a spread of Ca–O bond distances ranging from 2.27–2.48 Å. Zn2+ is bonded to six O2- atoms to form distorted ZnO6 pentagonal pyramids that share corners with two equivalent TeO6 octahedra, edges with two equivalent TeO6 octahedra, edges with two equivalent ZnO6 pentagonal pyramids, and edges with four equivalent CaO6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 30°. There are a spread of Zn–O bond distances ranging from 2.05–2.33 Å. Te6+ is bonded to six O2- atoms to form TeO6 octahedra that share corners with three equivalent CaO6 pentagonal pyramids, corners with three equivalent ZnO6 pentagonal pyramids, edges with three equivalent CaO6 pentagonal pyramids, and edges with three equivalent ZnO6 pentagonal pyramids. All Te–O bond lengths are 1.96 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded to one Ca2+, two equivalent Zn2+, and one Te6+ atom to form a mixture of distorted corner and edge-sharing OCaZn2Te trigonal pyramids. In the second O2- site, O2- is bonded in a distorted rectangular see-saw-like geometry to two equivalent Ca2+, one Zn2+, and one Te6+ atom.