Insertion Compounds of 2H-TaS(2).NH(3)

A new method of intercalating metals into layer compounds has been developed using electrolytic generation from the salt solution in ammonia. The results suggest that metals that are soluble in ammonia will form a homogeneous metal-ammonia intercalate layer, NH₃·M_x, when x is less than the limiting solubility of M in NH₃. The superconducting transition temperature (T_c) was found to increase as the c-axis expansion [2δ = c(TaS₂·NH₃·M_x) - c(2H-TaS₂)] decreased when M = lithium, sodium, and potassium. Of all the alkali metals, potassium gave the most stable compounds and the highest T_c, 4.7°K.