DOI: 10.17188/1718370
title: Materials Data on Sr4Nd3Ta2Al5O21 by Materials Project

description: Sr4Nd3Ta2Al5O21 is (Cubic) Perovskite-derived structured and crystallizes in the trigonal R-3m space group. The structure is three-dimensional. there are two inequivalent Sr2+ sites. In the first Sr2+ site, Sr2+ is bonded to twelve O2- atoms to form SrO12 cuboctahedra that share corners with three equivalent NdO12 cuboctahedra, corners with nine SrO12 cuboctahedra, faces with six SrO12 cuboctahedra, faces with four equivalent TaO6 octahedra, and faces with four AlO6 octahedra. There are a spread of Sr–O bond distances ranging from 2.73–2.80 Å. In the second Sr2+ site, Sr2+ is bonded to twelve O2- atoms to form SrO12 cuboctahedra that share corners with three equivalent NdO12 cuboctahedra, corners with nine SrO12 cuboctahedra, faces with three equivalent SrO12 cuboctahedra, faces with three equivalent NdO12 cuboctahedra, faces with three equivalent TaO6 octahedra, and faces with five AlO6 octahedra. There are a spread of Sr–O bond distances ranging from 2.71–2.85 Å. There are two inequivalent Nd3+ sites. In the first Nd3+ site, Nd3+ is bonded to twelve O2- atoms to form NdO12 cuboctahedra that share corners with three equivalent SrO12 cuboctahedra, corners with nine equivalent NdO12 cuboctahedra, faces with three equivalent SrO12 cuboctahedra, faces with three equivalent NdO12 cuboctahedra, a faceface with one TaO6 octahedra, and faces with seven AlO6 octahedra. There are a spread of Nd–O bond distances ranging from 2.59–2.81 Å. In the second Nd3+ site, Nd3+ is bonded to twelve O2- atoms to form NdO12 cuboctahedra that share corners with six equivalent SrO12 cuboctahedra, corners with six equivalent NdO12 cuboctahedra, faces with six equivalent NdO12 cuboctahedra, and faces with eight AlO6 octahedra. There are six shorter (2.65 Å) and six longer (2.73 Å) Nd–O bond lengths. Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with six AlO6 octahedra, a faceface with one NdO12 cuboctahedra, and faces with seven SrO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–1°. There is three shorter (1.98 Å) and three longer (1.99 Å) Ta–O bond length. There are three inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to six equivalent O2- atoms to form AlO6 octahedra that share corners with six equivalent TaO6 octahedra and faces with eight SrO12 cuboctahedra. The corner-sharing octahedral tilt angles are 0°. All Al–O bond lengths are 1.91 Å. In the second Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with three equivalent TaO6 octahedra, corners with three equivalent AlO6 octahedra, faces with four SrO12 cuboctahedra, and faces with four NdO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 1–3°. There is three shorter (1.90 Å) and three longer (1.92 Å) Al–O bond length. In the third Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with six AlO6 octahedra, a faceface with one SrO12 cuboctahedra, and faces with seven NdO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 0–3°. There is three shorter (1.90 Å) and three longer (1.94 Å) Al–O bond length. There are four inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted linear geometry to four Sr2+, one Ta5+, and one Al3+ atom. In the second O2- site, O2- is bonded in a distorted linear geometry to three Sr2+, one Nd3+, one Ta5+, and one Al3+ atom. In the third O2- site, O2- is bonded in a distorted linear geometry to one Sr2+, three Nd3+, and two Al3+ atoms. In the fourth O2- site, O2- is bonded in a distorted linear geometry to four Nd3+ and two equivalent Al3+ atoms.