DOI: 10.17188/1276909
title: Materials Data on Ta3Bi7O18 by Materials Project

description: Bi7Ta3O18 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are two inequivalent Ta5+ sites. In the first Ta5+ site, Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with three equivalent TaO6 octahedra and a cornercorner with one BiO7 pentagonal bipyramid. The corner-sharing octahedra tilt angles range from 13–34°. There are a spread of Ta–O bond distances ranging from 1.92–2.15 Å. In the second Ta5+ site, Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with two equivalent TaO6 octahedra, corners with two equivalent BiO7 pentagonal bipyramids, and edges with four BiO7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 32°. There are four shorter (2.00 Å) and two longer (2.02 Å) Ta–O bond lengths. There are six inequivalent Bi3+ sites. In the first Bi3+ site, Bi3+ is bonded to seven O2- atoms to form distorted BiO7 pentagonal bipyramids that share corners with two equivalent TaO6 octahedra, corners with two equivalent BiO7 pentagonal bipyramids, edges with two equivalent TaO6 octahedra, and edges with two equivalent BiO7 pentagonal bipyramids. The corner-sharing octahedral tilt angles are 37°. There are a spread of Bi–O bond distances ranging from 2.25–2.92 Å. In the second Bi3+ site, Bi3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Bi–O bond distances ranging from 2.12–2.76 Å. In the third Bi3+ site, Bi3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Bi–O bond distances ranging from 2.32–2.68 Å. In the fourth Bi3+ site, Bi3+ is bonded in a 7-coordinate geometry to seven O2- atoms. There are a spread of Bi–O bond distances ranging from 2.22–2.98 Å. In the fifth Bi3+ site, Bi3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Bi–O bond distances ranging from 2.10–2.84 Å. In the sixth Bi3+ site, Bi3+ is bonded to seven O2- atoms to form distorted BiO7 pentagonal bipyramids that share corners with two equivalent TaO6 octahedra, corners with two equivalent BiO7 pentagonal bipyramids, and edges with two equivalent TaO6 octahedra. The corner-sharing octahedral tilt angles are 46°. There are a spread of Bi–O bond distances ranging from 2.30–2.78 Å. There are thirteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to four Bi3+ atoms. In the second O2- site, O2- is bonded to four Bi3+ atoms to form corner-sharing OBi4 tetrahedra. In the third O2- site, O2- is bonded in a 4-coordinate geometry to one Ta5+ and three Bi3+ atoms. In the fourth O2- site, O2- is bonded in a 1-coordinate geometry to one Ta5+ and two Bi3+ atoms. In the fifth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two equivalent Ta5+ and one Bi3+ atom. In the sixth O2- site, O2- is bonded in a 4-coordinate geometry to one Ta5+ and three Bi3+ atoms. In the seventh O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two equivalent Ta5+ and two Bi3+ atoms. In the eighth O2- site, O2- is bonded to four Bi3+ atoms to form a mixture of corner and edge-sharing OBi4 tetrahedra. In the ninth O2- site, O2- is bonded in a 3-coordinate geometry to one Ta5+ and two Bi3+ atoms. In the tenth O2- site, O2- is bonded in a 3-coordinate geometry to one Ta5+ and two equivalent Bi3+ atoms. In the eleventh O2- site, O2- is bonded to four Bi3+ atoms to form a mixture of corner and edge-sharing OBi4 tetrahedra. In the twelfth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two equivalent Ta5+ and two Bi3+ atoms. In the thirteenth O2- site, O2- is bonded in a linear geometry to two equivalent Ta5+ atoms.