Syntheses and characterization of new quaternary sulfides of a m sn s a alkali metal m zn cd ag systems

Abstract

The syntheses characterization and properties of fifteen new quaternary sulfides of AMSnS A Alkali metal M Cd Zn Ag systems are described in this thesis These new compounds were synthesized by solid state reactions and molten flux methods and characterized by Xray diffraction and spectroscopic techniques They are semiconductors newlineCs2CdSn2S6 Rb2CdSn2S6 K2CdSn2S6 Cs2CdSn3S8 Rb2CdSn3S8 K2CdSn3S8 Na2CdSn3S8 Cs2ZnSn3S8 and Rb2ZnSn3S8 compounds are the new intended A2CdSn2S6 and A2MSn3S8 M Cd Zn sulfides synthesized Isostructural Cs2CdSn2S6 and Rb2CdSn2S6 compounds have noncentrosymmetric threedimensional structure containing tetrahedral CdSn2S6 2 anionic framework and show secondharmonicgeneration SHG response K2CdSn2S6 has two centrosymmetric layered structural modifications and which contain tetrahedral and octahedral CdSn2S6 2 framework structures respectively Cs2ZnSn3S8 Rb2ZnSn3S8 Cs2CdSn3S8 and Rb2CdSn3S8 compounds have twodimensional and threedimensional modifications in which the tetrahedrally coordinated Zn2 Cd2 and Sn4 ions in their MSn3S8 2 anionic frameworks are ordered and disordered respectively The modifications on heating transform to modifications newlineK2CdSn2S6 K2CdSn3S8 and Na2CdSn3S8 compounds have layered structures The potassium and sodium ions reside between the anionic CdSn2S6 2 and CdSn3S8 2 layers in which the Cd2 and Sn4 ions are disordered and octahedrally coordinated They undergo facile ionexchange at room temperature in aqueous medium with different proportions of hydronium ions and other mono di and trivalent cations These three compounds are potentially useful for nuclear waste disposal newlineKAgSnS3 and Rb2Ag2SnS4 compounds have noncentrosymmetric threedimensional and centrosymmetric twodimensional structures in which silver ions are linearly and tetrahedrally coordinated respectively newline newline