UNIVERSAL SCALING OF THE CONDUCTIVITY RELAXATION IN CRYSTALLINE IONICCONDUCTORS

We present complex admittance measurements on single-crystal yttria-st abilized zirconia and polycrystalline Li0.5La0.5TiO3 over the frequenc y range 5 Hz to 30 MHz and at temperatures ranging between 150 and 650 K. Electric-field relaxation in both fast ionic conductors can be des cribed using Kohlrausch-Williams-Watts decay functions, but departures are observed at high frequencies and low temperatures. Electric modul us data obey the Dixon-Nagel scaling that has been proposed to be univ ersal in describing the relaxation processes in supercooled liquids. O ur data provide broader universality to the Dixon-Nagel scaling, and a re interpreted in terms of the influence of mobile ions positional dis order on the relaxation dynamics.