Materials Data on FeAs2Pb2O9 by Materials Project
FePb2As2O9 crystallizes in the monoclinic P2_1/m space group. The structure is three-dimensional. Fe2+ is bonded to six O2- atoms to form FeO6 octahedra that share corners with four AsO4 tetrahedra and edges with two equivalent FeO6 octahedra. There are a spread of Fe–O bond distances ranging from 1.89–2.09 Å. There are two inequivalent Pb3+ sites. In the first Pb3+ site, Pb3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Pb–O bond distances ranging from 2.45–2.95 Å. In the second Pb3+ site, Pb3+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Pb–O bond distances ranging from 2.59–2.81 Å. There are two inequivalent As5+ sites. In the first As5+ site, As5+ is bonded to four O2- atoms to form AsO4 tetrahedra that share corners with two equivalent FeO6 octahedra. The corner-sharing octahedral tilt angles are 56°. There are a spread of As–O bond distances ranging from 1.69–1.76 Å. In the second As5+ site, As5+ is bonded to four O2- atoms to form AsO4 tetrahedra that share corners with two equivalent FeO6 octahedra. The corner-sharing octahedral tilt angles are 46°. There are a spread of As–O bond distances ranging from 1.70–1.77 Å. There are seven inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to one Pb3+ and one As5+ atom. In the second O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Pb3+ and one As5+ atom. In the third O2- site, O2- is bonded in a distorted T-shaped geometry to two equivalent Fe2+ and one As5+ atom. In the fourth O2- site, O2- is bonded in a distorted water-like geometry to two equivalent Fe2+ and one Pb3+ atom. In the fifth O2- site, O2- is bonded in a distorted single-bond geometry to one Pb3+ and one As5+ atom. In the sixth O2- site, O2- is bonded in a distorted single-bond geometry to two Pb3+ and one As5+ atom. In the seventh O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one Fe2+, two Pb3+, and one As5+ atom.