Synthesis, crystal and band structures, and optical properties of a novel quaternary mercury and cadmium chalcogenidehalide: (Hg2Cd2S2Br)Br

Abstract

A novel quaternary mercury and cadmium chalcogenidehalide, (Hg₂Cd₂S₂Br)Br (1), has been prepared by solid-state reaction and structurally characterized by single crystal X-ray diffraction analysis. The structure of 1 is composed of parallel slabs stacking with -ABAB- mode via linearly coordinated Hg atoms to form a 3D cationic network with the channels being occupied by discrete Br anions, in which the slab consists of interlinks of linear (HgS₂Br₂) tetrahedral chains and (CdS₂Br) trigonal chains. The optical properties were investigated in terms of the diffuse reflectance and Fourier transform infrared spectra. The electronic band structure along with density of states (DOS) calculated by DFT method indicates that the present compound is a semiconductor with an indirect band gap, and that the optical absorption is mainly originated from the charge transitions from Br-4p and S-3p to Cd-5s and Hg-6s states.