DOE OSTI2020
Ba6Nd2Al4O15 crystallizes in the monoclinic Cc space group. The structure is three-dimensional. there are six inequivalent Ba2+ sites. In the first Ba2+ site, Ba2+ is bonded to six O2- atoms to form BaO6 octahedra that share corners with six AlO4 tetrahedra and faces with two equivalent BaO6 octahedra. There are a spread of Ba–O bond distances ranging from 2.58–2.87 Å. In the second 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 2.76–3.27 Å. In the third 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 2.78–3.28 Å. In the fourth 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 2.80–3.27 Å. In the fifth Ba2+ site, Ba2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Ba–O bond distances ranging from 2.57–2.88 Å. In the sixth Ba2+ site, Ba2+ is bonded to twelve O2- atoms to form distorted BaO12 cuboctahedra that share faces with two equivalent AlO6 octahedra and faces with three AlO4 tetrahedra. There are a spread of Ba–O bond distances ranging from 2.72–3.20 Å. There are two inequivalent Nd3+ sites. In the first Nd3+ site, Nd3+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Nd–O bond distances ranging from 2.43–2.67 Å. In the second Nd3+ site, Nd3+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Nd–O bond distances ranging from 2.39–2.69 Å. There are four inequivalent Al3+ sites. In the first Al3+ site, Al3+ is bonded to six O2- atoms to form AlO6 octahedra that share corners with three AlO4 tetrahedra and faces with two equivalent BaO12 cuboctahedra. There are a spread of Al–O bond distances ranging from 1.84–2.21 Å. In the second Al3+ site, Al3+ is bonded to four O2- atoms to form AlO4 tetrahedra that share a cornercorner with one AlO6 octahedra, corners with two equivalent BaO6 octahedra, and a faceface with one BaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 6–64°. There are a spread of Al–O bond distances ranging from 1.76–1.82 Å. In the third Al3+ site, Al3+ is bonded to four O2- atoms to form AlO4 tetrahedra that share a cornercorner with one AlO6 octahedra, corners with two equivalent BaO6 octahedra, and a faceface with one BaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 6–66°. There are a spread of Al–O bond distances ranging from 1.77–1.85 Å. In the fourth Al3+ site, Al3+ is bonded to four O2- atoms to form AlO4 tetrahedra that share a cornercorner with one AlO6 octahedra, corners with two equivalent BaO6 octahedra, and a faceface with one BaO12 cuboctahedra. The corner-sharing octahedra tilt angles range from 6–68°. There are a spread of Al–O bond distances ranging from 1.76–1.83 Å. There are fifteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to five Ba2+ and one Al3+ atom. In the second O2- site, O2- is bonded in a 1-coordinate geometry to five Ba2+ and one Al3+ atom. In the third O2- site, O2- is bonded in a 1-coordinate geometry to five Ba2+ and one Al3+ atom. In the fourth O2- site, O2- is bonded in a 6-coordinate geometry to two Ba2+, two Nd3+, and two Al3+ atoms. In the fifth O2- site, O2- is bonded in a 6-coordinate geometry to three Ba2+, one Nd3+, and two Al3+ atoms. In the sixth O2- site, O2- is bonded in a 6-coordinate geometry to three Ba2+, one Nd3+, and two Al3+ atoms. In the seventh O2- site, O2- is bonded in a distorted octahedral geometry to four Ba2+, one Nd3+, and one Al3+ atom. In the eighth O2- site, O2- is bonded in a 1-coordinate geometry to four Ba2+, one Nd3+, and one Al3+ atom. In the ninth O2- site, O2- is bonded in a 6-coordinate geometry to three Ba2+, two equivalent Nd3+, and one Al3+ atom. In the tenth O2- site, O2- is bonded in a 1-coordinate geometry to three Ba2+, two equivalent Nd3+, and one Al3+ atom. In the eleventh O2- site, O2- is bonded in a 1-coordinate geometry to four Ba2+, one Nd3+, and one Al3+ atom. In the twelfth O2- site, O2- is bonded in a 1-coordinate geometry to four Ba2+, one Nd3+, and one Al3+ atom. In the thirteenth O2- site, O2- is bonded in a 1-coordinate geometry to three Ba2+, two equivalent Nd3+, and one Al3+ atom. In the fourteenth O2- site, O2- is bonded in a 1-coordinate geometry to four Ba2+, one Nd3+, and one Al3+ atom. In the fifteenth O2- site, O2- is bonded in a 1-coordinate geometry to four Ba2+, one Nd3+, and one Al3+ atom.