Crystal Structure of FePb4Sb6Se14 and its Structural Relationship with FePb3Sb4Se10

Abstract

AbstractSingle crystals of FePb4Sb6Se14, were obtained from solid‐state combination of high purity elemental powders at 873K for three days. Single crystal X‐ray structure determination revealed that the compound crystallizes in the monoclinic space group P21/c (no. 14) and adopts the structure of Jamesonite (FePb4Sb6S14). The structure contains two crystallographically independent lead atoms with monocapped and bicapped trigonal prismatic coordinations, three antimony atoms located in a distorted octahedral environment and one iron atom occupying a flattened octahedral coordination. Neighboring monocapped and bicapped trigonal prims around lead atoms share faces and edges to build a corrugated layer parallel to the ac plane. Octahedrally coordinated antimony atoms share edges to form one‐dimensional (1D) {SbSe}∞ ribbons connecting adjacent corrugated layers. The distortion of the octahedral coordination around antimony atoms within the {SbSe}∞ ribbons with the longest bond pointing towards the center of the ribbon, suggests the stereochemical activity of antimony lone‐pairs with their electron clouds pointing towards the center of the {SbSe}∞ ribbon. The three dimensional framework resulting from the connectivity between the corrugated layers and the {SbSe}∞ ribbons, contains isolated cylindrical voids parallel to [100] which are filled by a 1D FenSe4n+2 straight chain of edge‐sharing FeSe6 octahedra. The crystal structure of FePb4Sb6Se14 is closely related to that of FePb3Sb4Se10 as they are formed by similar building units with different sizes.