Universal scaling of the conductivity relaxation in crystalline ionic conductors

Abstract

We present complex admittance measurements on single-crystal yttria-stabilized zirconia and polycrystalline Li_(0.5)La_(0.5)TiO_(3) over the frequency 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 described using Kohlrausch-Williams-Watts decay functions, but departures are observed at high frequencies and low temperatures. Electric modulus data obey the Dixon Nagel scaling that has been proposed to be universal in describing the relaxation processes in supercooled liquids. Our data provide broader universality to the Dixon-Nagel scaling, and are interpreted in terms of the influence of mobile ions positional disorder on the relaxation dynamics.