DOI: 10.17188/1309811
title: Materials Data on Ta6Pb4O19 by Materials Project

description: Pb4Ta6O19 crystallizes in the orthorhombic Imma space group. The structure is three-dimensional. there are four 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 34–44°. There are a spread of Ta–O bond distances ranging from 1.92–2.06 Å. In the second Ta5+ site, Ta5+ is bonded to six O2- atoms to form corner-sharing TaO6 octahedra. The corner-sharing octahedra tilt angles range from 34–41°. There is two shorter (1.98 Å) and four longer (2.01 Å) Ta–O bond length. In the third Ta5+ site, Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with six TaO6 octahedra, an edgeedge with one PbO8 hexagonal bipyramid, and edges with two equivalent PbO7 hexagonal pyramids. The corner-sharing octahedra tilt angles range from 41–42°. There are a spread of Ta–O bond distances ranging from 1.98–2.01 Å. In the fourth Ta5+ site, Ta5+ is bonded to six O2- atoms to form TaO6 octahedra that share corners with six TaO6 octahedra and edges with four equivalent PbO7 hexagonal pyramids. The corner-sharing octahedra tilt angles range from 38–40°. There is four shorter (1.99 Å) and two longer (2.00 Å) Ta–O bond length. There are three inequivalent Pb2+ sites. In the first Pb2+ site, Pb2+ is bonded to seven O2- atoms to form distorted PbO7 hexagonal pyramids that share edges with two equivalent PbO8 hexagonal bipyramids, an edgeedge with one PbO7 hexagonal pyramid, and edges with six TaO6 octahedra. There are a spread of Pb–O bond distances ranging from 2.22–2.88 Å. In the second Pb2+ site, Pb2+ is bonded in a hexagonal planar geometry to six O2- atoms. There are four shorter (2.67 Å) and two longer (2.69 Å) Pb–O bond lengths. In the third Pb2+ site, Pb2+ is bonded to eight O2- atoms to form PbO8 hexagonal bipyramids that share edges with two equivalent PbO8 hexagonal bipyramids, edges with four equivalent PbO7 hexagonal pyramids, and edges with six TaO6 octahedra. There are a spread of Pb–O bond distances ranging from 2.52–2.72 Å. There are eight inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two equivalent Ta5+ and two equivalent Pb2+ atoms. In the second O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Ta5+ and two equivalent Pb2+ atoms. 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 bent 150 degrees geometry to two Ta5+ atoms. In the fifth O2- site, O2- is bonded to four Pb2+ atoms to form corner-sharing OPb4 tetrahedra. In the sixth O2- site, O2- is bonded in a 2-coordinate geometry to two Ta5+ and two Pb2+ atoms. In the seventh O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two equivalent Ta5+ and two Pb2+ atoms. In the eighth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two Ta5+ and one Pb2+ atom.