Materials Data on Ba5Tm8Ni4O21 by Materials Project
Ba5Tm8Ni4O21 crystallizes in the tetragonal I4/m space group. The structure is three-dimensional. there are two inequivalent Ba2+ sites. In the first Ba2+ site, Ba2+ is bonded in a 10-coordinate geometry to ten O2- atoms. There are a spread of Ba–O bond distances ranging from 2.70–3.26 Å. In the second Ba2+ site, Ba2+ is bonded in a distorted q6 geometry to ten O2- atoms. There are two shorter (2.84 Å) and eight longer (2.90 Å) Ba–O bond lengths. There are two inequivalent Tm3+ sites. In the first Tm3+ site, Tm3+ is bonded to seven O2- atoms to form distorted TmO7 pentagonal bipyramids that share corners with three TmO7 pentagonal bipyramids, corners with two equivalent NiO5 trigonal bipyramids, edges with three equivalent TmO7 pentagonal bipyramids, edges with two equivalent NiO5 trigonal bipyramids, and faces with two equivalent TmO7 pentagonal bipyramids. There are a spread of Tm–O bond distances ranging from 2.27–2.40 Å. In the second Tm3+ site, Tm3+ is bonded to seven O2- atoms to form distorted TmO7 pentagonal bipyramids that share corners with two equivalent TmO7 pentagonal bipyramids, corners with two equivalent NiO5 trigonal bipyramids, edges with five TmO7 pentagonal bipyramids, an edgeedge with one NiO5 trigonal bipyramid, and a faceface with one NiO5 trigonal bipyramid. There are a spread of Tm–O bond distances ranging from 2.25–2.38 Å. Ni2+ is bonded to five O2- atoms to form NiO5 trigonal bipyramids that share corners with four TmO7 pentagonal bipyramids, edges with three TmO7 pentagonal bipyramids, and a faceface with one TmO7 pentagonal bipyramid. There are a spread of Ni–O bond distances ranging from 2.02–2.08 Å. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a 6-coordinate geometry to two Ba2+, three Tm3+, and one Ni2+ atom. In the second O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Ba2+, three Tm3+, and one Ni2+ atom. In the third O2- site, O2- is bonded to two equivalent Ba2+ and four equivalent Tm3+ atoms to form distorted corner-sharing OBa2Tm4 octahedra. The corner-sharing octahedral tilt angles are 0°. In the fourth O2- site, O2- is bonded to four equivalent Ba2+, one Tm3+, and one Ni2+ atom to form a mixture of distorted edge and corner-sharing OBa4TmNi octahedra. The corner-sharing octahedral tilt angles are 3°.