PbMnIn₂S₅: Synthesis, Structure, and Properties

Abstract

The first manganese member in a Pb–M–In–Q system, PbMnIn₂S₅, has been discovered by a high-temperature solid-state reaction. It adopts a Sr₂Tl₂O₅ structure type in orthorhombic space group <i>Cmcm</i> (No. 63) with <i>a</i> = 3.896(2) Å, <i>b</i> = 12.731(7) Å, <i>c</i> = 15.770(9) Å, and <i>Z</i> = 1. The structure consists of corrugated layers made by (In1/Mn1)­S₆ octahedra that are further interconnected by chains of edge-sharing (In2/Mn2)­S₆ octahedra into a three-dimensional framework; Pb²⁺ cations are coordinated in PbS₈ bicapped triangular prisms that are face-shared along the <i>a</i> direction. The crystallographically distinguished octahedrally coordinated 8<i>f</i> and 4<i>b</i> sites are disordered by Mn and In atoms. Such a structure allows antiferromagnetic interactions between the high-spin Mn²⁺ anions. The optical band gap is measured to be about 1.45 eV