Materials Data on Sr4NbAlO8 by Materials Project

Abstract

Sr4AlNbO8 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are four inequivalent Sr2+ sites. In the first Sr2+ site, Sr2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Sr–O bond distances ranging from 2.44–2.88 Å. In the second Sr2+ site, Sr2+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Sr–O bond distances ranging from 2.41–2.96 Å. In the third Sr2+ site, Sr2+ is bonded to six O2- atoms to form distorted SrO6 pentagonal pyramids that share corners with three equivalent NbO6 octahedra and corners with three equivalent AlO4 tetrahedra. The corner-sharing octahedra tilt angles range from 4–21°. There are a spread of Sr–O bond distances ranging from 2.43–2.62 Å. In the fourth Sr2+ site, Sr2+ is bonded in a 10-coordinate geometry to ten O2- atoms. There are a spread of Sr–O bond distances ranging from 2.58–3.16 Å. Nb5+ is bonded to six O2- atoms to form NbO6 octahedra that share corners with two equivalent NbO6 octahedra, corners with three equivalent SrO6 pentagonal pyramids, and a cornercorner with one AlO4 tetrahedra. The corner-sharing octahedral tilt angles are 9°. There are a spread of Nb–O bond distances ranging from 1.93–2.15 Å. Al3+ is bonded to four O2- atoms to form AlO4 tetrahedra that share a cornercorner with one NbO6 octahedra and corners with three equivalent SrO6 pentagonal pyramids. The corner-sharing octahedral tilt angles are 20°. There are a spread of Al–O bond distances ranging from 1.77–1.82 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a 1-coordinate geometry to four Sr2+ and one Al3+ atom. In the second O2- site, O2- is bonded in a 4-coordinate geometry to three Sr2+, one Nb5+, and one Al3+ atom. In the third O2- site, O2- is bonded in a 1-coordinate geometry to five Sr2+ and one Nb5+ atom. In the fourth O2- site, O2- is bonded in a 4-coordinate geometry to three Sr2+ and one Al3+ atom. In the fifth O2- site, O2- is bonded in a distorted tetrahedral geometry to three Sr2+ and one Al3+ atom. In the sixth O2- site, O2- is bonded in a 3-coordinate geometry to four Sr2+ and two equivalent Nb5+ atoms. In the seventh O2- site, O2- is bonded in a 1-coordinate geometry to four Sr2+ and one Nb5+ atom. In the eighth O2- site, O2- is bonded in a 6-coordinate geometry to five Sr2+ and one Nb5+ atom.