Materials Data on CaTa4O14 by Materials Project

Abstract

CaTa4O14 crystallizes in the trigonal R-3m space group. The structure is three-dimensional. Ca is bonded to eight O atoms to form CaO8 hexagonal bipyramids that share edges with six equivalent TaO6 octahedra. There are two shorter (2.50 Å) and six longer (2.63 Å) Ca–O bond lengths. There are two inequivalent Ta sites. In the first Ta site, Ta is bonded to six equivalent O atoms to form corner-sharing TaO6 octahedra. The corner-sharing octahedral tilt angles are 37°. All Ta–O bond lengths are 1.98 Å. In the second Ta site, Ta is bonded to six O atoms to form TaO6 octahedra that share corners with six TaO6 octahedra and edges with two equivalent CaO8 hexagonal bipyramids. The corner-sharing octahedra tilt angles range from 37–42°. All Ta–O bond lengths are 1.99 Å. There are three inequivalent O sites. In the first O site, O is bonded in a distorted trigonal non-coplanar geometry to one Ca and two equivalent Ta atoms. In the second O site, O is bonded in a bent 150 degrees geometry to two Ta atoms. In the third O site, O is bonded in a single-bond geometry to one Ca atom.