The Li ion conductivity of Li0.5La0.5TiO3 was studied by using nuclear magnetic resonance and admittance spectroscopic techniques. It was found that the spin-lattice relaxation and electrical conductivity relaxation could be described in terms of stretched-exponential correlation functions of the form, exp[-(t/)], but involved various relaxation time scales (with  = 1.4 x 10-14s according to nuclear magnetic resonance data and  = 10-14s according to admittance spectroscopic data), and activation energies of 0.15 and 0.4eV, respectively. The value of  ranged from 1, according to spin lattice relaxation data, to 0.4, according to electric-field relaxation data. A microscopic activation energy of 0.15eV was deduced, for Li motion, by using either technique. The discrepancies between the techniques were explained in terms of frequency-dependent correlation effects.

C.León, M.L.Lucia, J.Santamaria, M.A.Paris, J.Sanz, A.Várez: Physical Review B, 1996, 54[1], 184-9