Materials Data on BaYCuNiO5 by Materials Project
BaYNiCuO5 crystallizes in the tetragonal P4mm space group. The structure is three-dimensional. Ba2+ is bonded to twelve O2- atoms to form BaO12 cuboctahedra that share corners with four equivalent BaO12 cuboctahedra, faces with four equivalent BaO12 cuboctahedra, faces with four equivalent NiO5 square pyramids, and faces with four equivalent CuO5 square pyramids. There are a spread of Ba–O bond distances ranging from 2.75–3.07 Å. Y3+ is bonded in a body-centered cubic geometry to eight O2- atoms. There are four shorter (2.39 Å) and four longer (2.42 Å) Y–O bond lengths. Ni4+ is bonded to five O2- atoms to form NiO5 square pyramids that share a cornercorner with one CuO5 square pyramid, corners with four equivalent NiO5 square pyramids, and faces with four equivalent BaO12 cuboctahedra. There is one shorter (1.97 Å) and four longer (1.98 Å) Ni–O bond length. Cu1+ is bonded to five O2- atoms to form CuO5 square pyramids that share a cornercorner with one NiO5 square pyramid, corners with four equivalent CuO5 square pyramids, and faces with four equivalent BaO12 cuboctahedra. There are four shorter (1.97 Å) and one longer (2.03 Å) Cu–O bond lengths. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Ba2+, two equivalent Y3+, and two equivalent Ni4+ atoms. In the second O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Ba2+, two equivalent Y3+, and two equivalent Cu1+ atoms. In the third O2- site, O2- is bonded to four equivalent Ba2+, one Ni4+, and one Cu1+ atom to form a mixture of edge and corner-sharing OBa4CuNi octahedra. The corner-sharing octahedral tilt angles are 1°.