The Nasub(x)Insub(x)Snsub(1-x)S2 intercalation-substitution compounds NMR study of 23Na and complex impedance measurements comparison with homologous series

In the Nasub(x)Insub(x)Snsub(1-x)S2 intercalation-substitution system, four phases occur as x decreases: a 3R one with octahedral environment of sodium (0.63 < x < 1), a 2H one with probably trigonal prismatic surrounding of the alkali metal (0.43 < x < 0.60), a 3R trigonal prismatic one (x approx. 0.40), and finally a 6R one, of the second stage, for x approx. 0.20. NMR study of 23Na and complex impedance measurements have been performed for different compositions. The x-dependence of the obtained results-quadrupole splitting. T1 relaxation times, and activation energies - is discussed, renembering that, when x decreases, the vacancy amount, the c/a ratio, and the structure covalency increase. The results, and also the hopping frequencies and the diffusion coefficients, are compared with those obtained for the similar systems Nasub(x)Insub(x)Zrsub(1-x)S2 and Nasub(x)Ysub(x)Zrsub(1-x)S2 (more ionic). (orig.)