DOE OSTI2020
Fe2Te2(PbO4)3 is Skutterudite-derived structured and crystallizes in the monoclinic Cc space group. The structure is three-dimensional. there are two inequivalent Fe3+ sites. In the first Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with two equivalent FeO6 octahedra, corners with two TeO6 octahedra, and an edgeedge with one TeO6 octahedra. The corner-sharing octahedra tilt angles range from 48–52°. There are a spread of Fe–O bond distances ranging from 1.98–2.17 Å. In the second Fe3+ site, Fe3+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with two TeO6 octahedra and edges with two TeO6 octahedra. The corner-sharing octahedra tilt angles range from 44–51°. There are a spread of Fe–O bond distances ranging from 2.03–2.13 Å. There are three inequivalent Pb2+ sites. In the first Pb2+ site, Pb2+ is bonded in a 8-coordinate geometry to eight O2- atoms. There are a spread of Pb–O bond distances ranging from 2.48–3.16 Å. In the second Pb2+ site, Pb2+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Pb–O bond distances ranging from 2.38–2.83 Å. In the third Pb2+ site, Pb2+ is bonded in a 2-coordinate geometry to eight O2- atoms. There are a spread of Pb–O bond distances ranging from 2.28–3.19 Å. There are two inequivalent Te6+ sites. In the first Te6+ site, Te6+ is bonded to six O2- atoms to form TeO6 octahedra that share corners with two FeO6 octahedra, corners with two equivalent TeO6 octahedra, and an edgeedge with one FeO6 octahedra. The corner-sharing octahedra tilt angles range from 48–51°. There are a spread of Te–O bond distances ranging from 1.92–2.02 Å. In the second Te6+ site, Te6+ is bonded to six O2- atoms to form TeO6 octahedra that share corners with two FeO6 octahedra and edges with two FeO6 octahedra. The corner-sharing octahedra tilt angles range from 44–52°. There are a spread of Te–O bond distances ranging from 1.94–1.99 Å. There are twelve inequivalent O2- sites. In the first O2- site, O2- is bonded in a 3-coordinate geometry to one Fe3+, one Pb2+, and one Te6+ atom. In the second O2- site, O2- is bonded in a 3-coordinate geometry to two Pb2+ and two equivalent Te6+ atoms. In the third O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Fe3+, two Pb2+, and one Te6+ atom. In the fourth O2- site, O2- is bonded in a distorted water-like geometry to one Fe3+, two equivalent Pb2+, and one Te6+ atom. In the fifth O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Fe3+ and two Pb2+ atoms. In the sixth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Fe3+, one Pb2+, and one Te6+ atom. In the seventh O2- site, O2- is bonded to one Fe3+, two equivalent Pb2+, and one Te6+ atom to form distorted corner-sharing OFeTePb2 trigonal pyramids. In the eighth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Fe3+, two Pb2+, and one Te6+ atom. In the ninth O2- site, O2- is bonded in a 2-coordinate geometry to one Fe3+, two equivalent Pb2+, and one Te6+ atom. In the tenth O2- site, O2- is bonded in a distorted water-like geometry to one Fe3+, two equivalent Pb2+, and one Te6+ atom. In the eleventh O2- site, O2- is bonded in a 3-coordinate geometry to one Fe3+, two Pb2+, and one Te6+ atom. In the twelfth O2- site, O2- is bonded in a 4-coordinate geometry to one Fe3+, two Pb2+, and one Te6+ atom.