Synthesis of lithium- and pyridine-intercalated superconductors Li- x (C5H5N)( y )SnSe2

Superconductors Li- x (C5H5N)( y )SnSe2 (x = 0.3-1.0) have been successfully synthesized by the intercalation of pyridine molecules together with Li+ ions into an insulator SnSe2 with the layered structure. The co-intercalation has been carried out by immersing powdery SnSe2 and Li metal in the organic solvent pyridine at 70 degrees C. The spacing between the adjacent Sn layers is expanded from similar to 6 to similar to 12 angstrom through the co-intercalation. It has been found that the superconducting transition temperature T (c) similar to 7.5-7.9 K is almost independent of Li-content x(Li) and the superconducting volume fraction has a maximum at x(Li) = 0.5.