An open-framework bimetallic chalcogenide structure K3Rb3Zn4Sn3Se13 built on a unique [Zn4Sn3Se16]12− cluster: synthesis, crystal structure, ion exchange and optical properties

Single crystals of K3Rb3Zn4Sn3Se13 were synthesized by solvothermal method. The building block in this structure is a [Zn4Sn3Se16]12− cluster which consists of four ZnSe4 and three SnSe4 tetrahedra connected through corner-sharing of Se atoms. The 3D network contains intersecting channels running parallel to the crystallographic [2 1 1], [1-1-1] and [12-1] directions. The disordered K+ and Rb+ cations reside in these channels. Ion exchange of Cs+ with disordered Rb+/K+ ions in the structure showed a partial replacement of 15.8%. Optical diffuse reflectance experiments were carried out and gave a sharp absorption edge at 2.6 eV.