DOI: 10.17188/1284258
title: Materials Data on Ta6Pb4O19 by Materials Project

description: Pb4Ta6O19 crystallizes in the monoclinic C2/m space group. The structure is three-dimensional. there are six inequivalent Ta5+ sites. In the first Ta5+ site, Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with six TaO6 octahedra, edges with two equivalent PbO8 hexagonal bipyramids, and edges with two equivalent PbO7 hexagonal pyramids. The corner-sharing octahedra tilt angles range from 34–42°. There are a spread of Ta–O bond distances ranging from 1.89–2.13 Å. In the second Ta5+ site, Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with six TaO6 octahedra, edges with two PbO8 hexagonal bipyramids, and edges with two equivalent PbO7 hexagonal pyramids. The corner-sharing octahedra tilt angles range from 36–42°. There are a spread of Ta–O bond distances ranging from 1.98–2.02 Å. In the third Ta5+ site, Ta5+ is bonded to six O2- atoms to form corner-sharing TaO6 octahedra. The corner-sharing octahedra tilt angles range from 40–43°. There are a spread of Ta–O bond distances ranging from 1.99–2.02 Å. In the fourth Ta5+ site, Ta5+ is bonded to six O2- atoms to form corner-sharing TaO6 octahedra. The corner-sharing octahedra tilt angles range from 34–42°. There are a spread of Ta–O bond distances ranging from 1.94–2.03 Å. In the fifth Ta5+ site, Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with six TaO6 octahedra and edges with six PbO8 hexagonal bipyramids. The corner-sharing octahedra tilt angles range from 41–42°. There are two shorter (2.00 Å) and four longer (2.01 Å) Ta–O bond lengths. In the sixth Ta5+ site, Ta5+ is bonded to six O2- atoms to form corner-sharing TaO6 octahedra. The corner-sharing octahedra tilt angles range from 36–40°. There are two shorter (1.99 Å) and four longer (2.02 Å) Ta–O bond lengths. There are five inequivalent Pb2+ sites. In the first Pb2+ site, Pb2+ is bonded in a hexagonal planar geometry to six O2- atoms. There are a spread of Pb–O bond distances ranging from 2.60–2.75 Å. In the second Pb2+ site, Pb2+ is bonded in a hexagonal planar geometry to six O2- atoms. There are four shorter (2.68 Å) and two longer (2.70 Å) Pb–O bond lengths. In the third Pb2+ site, Pb2+ is bonded to seven O2- atoms to form distorted PbO7 hexagonal pyramids that share edges with three PbO8 hexagonal bipyramids and edges with six TaO6 octahedra. There are a spread of Pb–O bond distances ranging from 2.14–2.83 Å. In the fourth Pb2+ site, Pb2+ is bonded to eight O2- atoms to form distorted PbO8 hexagonal bipyramids that share edges with four equivalent PbO8 hexagonal bipyramids, edges with two equivalent PbO7 hexagonal pyramids, and edges with six TaO6 octahedra. There are a spread of Pb–O bond distances ranging from 2.43–2.80 Å. In the fifth Pb2+ site, Pb2+ is bonded to eight O2- atoms to form PbO8 hexagonal bipyramids that share edges with four PbO8 hexagonal bipyramids, edges with two equivalent PbO7 hexagonal pyramids, and edges with six TaO6 octahedra. There are a spread of Pb–O bond distances ranging from 2.44–2.74 Å. There are thirteen inequivalent O2- sites. In the first O2- site, O2- is bonded in a bent 150 degrees geometry to two Ta5+ atoms. In the second O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two Ta5+ and one Pb2+ atom. In the third O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two Ta5+ and one Pb2+ atom. In the fourth O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Ta5+ and two Pb2+ atoms. In the fifth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two Ta5+ and one Pb2+ atom. In the sixth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two Ta5+ and one Pb2+ atom. In the seventh O2- site, O2- is bonded in a bent 150 degrees geometry to two Ta5+ atoms. In the eighth O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Ta5+ and two Pb2+ atoms. In the ninth O2- site, O2- is bonded in a 2-coordinate geometry to two Ta5+ and two Pb2+ atoms. In the tenth O2- site, O2- is bonded in a 2-coordinate geometry to two Ta5+ and two equivalent Pb2+ atoms. In the eleventh O2- site, O2- is bonded to four Pb2+ atoms to form distorted corner-sharing OPb4 tetrahedra. In the twelfth O2- site, O2- is bonded in a 2-coordinate geometry to two Ta5+ and two Pb2+ atoms. In the thirteenth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two equivalent Ta5+ and two Pb2+ atoms.