Materials Data on CaNb2CuBrO7 by Materials Project

CaNb2CuO7Br crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. Ca2+ is bonded to twelve O2- atoms to form CaO12 cuboctahedra that share corners with four equivalent CaO12 cuboctahedra, faces with four equivalent CaO12 cuboctahedra, and faces with eight equivalent NbO6 octahedra. There are eight shorter (2.67 Å) and four longer (2.80 Å) Ca–O bond lengths. Nb5+ is bonded to six O2- atoms to form distorted NbO6 octahedra that share corners with five equivalent NbO6 octahedra and faces with four equivalent CaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–20°. There are a spread of Nb–O bond distances ranging from 1.86–2.13 Å. Cu3+ is bonded in a distorted linear geometry to two equivalent O2- and four equivalent Br1- atoms. Both Cu–O bond lengths are 1.80 Å. All Cu–Br bond lengths are 2.80 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Ca2+ and two equivalent Nb5+ atoms. In the second O2- site, O2- is bonded in a linear geometry to one Nb5+ and one Cu3+ atom. In the third O2- site, O2- is bonded in a distorted linear geometry to four equivalent Ca2+ and two equivalent Nb5+ atoms. Br1- is bonded in a square co-planar geometry to four equivalent Cu3+ atoms.