DOI: 10.17188/1723700
title: Materials Data on BaNa2Sr6Al6(OF16)2 by Materials Project

description: Na2BaSr6Al6(OF16)2 crystallizes in the monoclinic Cm space group. The structure is three-dimensional. there are two inequivalent Na sites. In the first Na site, Na is bonded to two O and four F atoms to form NaO2F4 octahedra that share corners with two equivalent NaO2F4 octahedra and corners with four AlF6 octahedra. The corner-sharing octahedra tilt angles range from 44–75°. There are one shorter (2.32 Å) and one longer (2.33 Å) Na–O bond lengths. There are two shorter (2.30 Å) and two longer (2.32 Å) Na–F bond lengths. In the second Na site, Na is bonded to two O and four F atoms to form distorted NaO2F4 octahedra that share corners with two equivalent NaO2F4 octahedra and corners with four AlF6 octahedra. The corner-sharing octahedra tilt angles range from 54–75°. Both Na–O bond lengths are 2.27 Å. There are two shorter (2.46 Å) and two longer (2.47 Å) Na–F bond lengths. Ba is bonded in a 12-coordinate geometry to nine F atoms. There are a spread of Ba–F bond distances ranging from 2.70–2.87 Å. There are four inequivalent Sr sites. In the first Sr site, Sr is bonded in a 7-coordinate geometry to one O and eight F atoms. The Sr–O bond length is 2.45 Å. There are a spread of Sr–F bond distances ranging from 2.52–2.99 Å. In the second Sr site, Sr is bonded in a 7-coordinate geometry to one O and eight F atoms. The Sr–O bond length is 2.47 Å. There are a spread of Sr–F bond distances ranging from 2.50–2.99 Å. In the third Sr site, Sr is bonded in a 10-coordinate geometry to ten F atoms. There are a spread of Sr–F bond distances ranging from 2.53–2.98 Å. In the fourth Sr site, Sr is bonded in a 9-coordinate geometry to nine F atoms. There are a spread of Sr–F bond distances ranging from 2.54–2.94 Å. There are four inequivalent Al sites. In the first Al site, Al is bonded to six F atoms to form corner-sharing AlF6 octahedra. The corner-sharing octahedral tilt angles are 36°. There is one shorter (1.81 Å) and five longer (1.83 Å) Al–F bond length. In the second Al site, Al is bonded to six F atoms to form corner-sharing AlF6 octahedra. The corner-sharing octahedral tilt angles are 36°. There are a spread of Al–F bond distances ranging from 1.81–1.85 Å. In the third Al site, Al is bonded to six F atoms to form AlF6 octahedra that share a cornercorner with one AlF6 octahedra and corners with two NaO2F4 octahedra. The corner-sharing octahedra tilt angles range from 36–54°. There are a spread of Al–F bond distances ranging from 1.80–1.87 Å. In the fourth Al site, Al is bonded to six F atoms to form AlF6 octahedra that share a cornercorner with one AlF6 octahedra and corners with two NaO2F4 octahedra. The corner-sharing octahedra tilt angles range from 36–57°. There are a spread of Al–F bond distances ranging from 1.80–1.87 Å. There are two inequivalent O sites. In the first O site, O is bonded to two Na and two equivalent Sr atoms to form ONa2Sr2 tetrahedra that share corners with two equivalent ONa2Sr2 tetrahedra and edges with two equivalent FNaSr2Al tetrahedra. In the second O site, O is bonded to two Na and two equivalent Sr atoms to form ONa2Sr2 tetrahedra that share corners with two equivalent ONa2Sr2 tetrahedra and corners with two equivalent FNaSr2Al tetrahedra. There are eighteen inequivalent F sites. In the first F site, F is bonded in a 1-coordinate geometry to three Sr and one Al atom. In the second F site, F is bonded in a 1-coordinate geometry to one Ba, two Sr, and one Al atom. In the third F site, F is bonded in a distorted linear geometry to one Sr and one Al atom. In the fourth F site, F is bonded in a distorted linear geometry to one Sr and one Al atom. In the fifth F site, F is bonded in a bent 150 degrees geometry to two Al atoms. In the sixth F site, F is bonded in a bent 150 degrees geometry to two Al atoms. In the seventh F site, F is bonded in a 1-coordinate geometry to one Na, one Sr, and one Al atom. In the eighth F site, F is bonded in a 3-coordinate geometry to one Na, one Sr, and one Al atom. In the ninth F site, F is bonded in a 1-coordinate geometry to three Sr and one Al atom. In the tenth F site, F is bonded in a distorted single-bond geometry to one Ba, two equivalent Sr, and one Al atom. In the eleventh F site, F is bonded in a 4-coordinate geometry to one Na, one Ba, one Sr, and one Al atom. In the twelfth F site, F is bonded to one Na, two Sr, and one Al atom to form distorted FNaSr2Al tetrahedra that share a cornercorner with one ONa2Sr2 tetrahedra, an edgeedge with one ONa2Sr2 tetrahedra, and an edgeedge with one FNaSr2Al tetrahedra. In the thirteenth F site, F is bonded in a distorted single-bond geometry to one Ba, one Sr, and one Al atom. In the fourteenth F site, F is bonded in a distorted single-bond geometry to two Sr and one Al atom. In the fifteenth F site, F is bonded in a 2-coordinate geometry to two Sr and one Al atom. In the sixteenth F site, F is bonded in a 1-coordinate geometry to two Sr and one Al atom. In the seventeenth F site, F is bonded in a 1-coordinate geometry to three Sr and one Al atom. In the eighteenth F site, F is bonded in a 1-coordinate geometry to one Ba, two Sr, and one Al atom.