Investigations of Mn(pyr)(aq)+2 and pyridine intercalated Cd2P2S6 lattices: mechanism of intercalation and perturbation of the host lattice

Abstract

The lamellar transition metal Chalocogeno-Phosphates (M2P2S6) form an important family of two-dimensional semiconducting materials. The lamellar structure is formed by stacking S-M-(P-P)-S units along a unique crystallographic axis. Under appropriate conditions, guest species can enter the space between the layers to form intercalation compounds. Two main mechanisms are presently proposed for the intercalation reaction: electron transfer from guest to host lattice and cation exchange between cationic intercalated species and lattice metal ions. Both mechanisms create structural and electronic perturbations which often result in a dramatic modification of the chemical and physical properties of the host lattice.This paper describes the experimental evidence for the mechanisms of intercalation and creation of perturbation in the host lattices. Electron Spin Resonance spectroscopy has revealed cation migration between inter- and intralamellar cationic sites, supporting the cation exchange mechanism for the intercalation of solvated cationic species. Photoluminescence studies of Lewis base molecules intercalated into M2P2S6 have shown a broadening of the conduction band due to the insertion of defects level near the band edges. Complementary measurements utilizing Optically detected Magnetic Resonance Spectroscopy demonstrated the presence of a strongly coupled donor-acceptor pair created upon intercalation via charge transfer mechanism.