Lithium NMR study on Li-ion conducting A-site deficient perovskites

The spin-lattice relaxation time T-1 of Li-7 and the conductivity spectra were measured to investigate the ionic conduction behavior in the A-site deficient perovskite solid solutions alpha- and beta -La0.56Li0.33TiO3 as a function of the order parameter (S) of the alternate arrangement of the La3+-rich and (Li+-vacancy)-rich layers. The major findings are as follows: 1) a similar extent of the strong Li-Li correlation that the Kohlrausch exponent beta was similar to0.32 was observed irrespective of S. 2) the temperature dependence of the correlation time obtained from T-1 indicates that the uniformity of the Li-sites decreases with increasing S. 3) in spite of a large difference in S, their conductivity spectra resembled each other; a similar power-law dependence with a single power-exponent similar to1.3 implies the presence of the unfavorable A-sites that hardly contribute to the dc-conductivity.