ATOMIC-FORCE MICROSCOPY STUDY OF LAYERED MNPS3 AND ITS INTERCALATION COMPOUNDS

The layered phase MnPS3 and its intercalation compounds Mn1-xPS3G2x (G = potassium, pyridinium, and tetramethylammonium cations) were examin e by atomic force microscopy (AFM). These compounds have layers made u p of close packed P2S6(4-) ions with their P-P bonds perpendicular to the layer plane. The atomic-resolution AFM images observed for these c ompounds are characterized by two hexagonal patterns, i.e., the regula r and superstructure patterns of the approximately 3.5 and approximate ly 6.5 angstrom periods, respectively. This finding was interpreted by calculating the total electron density plots of MnPS3 layers in which the P2S6(4-) ions tilt slightly from their perpendicular arrangement. The regular pattern is explained by the surface sulfur atoms of the t opmost layer and the superstructure by the pattern of the protruded su rface sulfur atoms that results when the P2S6(4-) ions tilt slightly. The tilting of the P2S6(4-) ions may be caused by the guest species pr esent between the layers.