Relationship between charge carrier relaxation and peculiarities of electric response in some solid oxygen ion conductors

The electrical properties (impedance, dielectric permittivity, and electric modulus) of various zirconia and ceria based oxygen ion conductors have been investigated in a broad frequency (from 1 Hz to 10 GHz) and temperature (from ambient to about 1100 K) ranges by impedance spectroscopy. A plateau of dielectric permittivity in frequencies lower than the frequency of impedance's imaginary part's peak was observed in the case of yttrium and calcium stabilized zirconia single crystals. The temperature dependence of the dielectriC permittivity's plateau's value has been determined, which was found to decrease with increasing temperature. The temperature behaviour of characteristic frequencies, corresponding to peak values of the imaginary parts of electric modulus f(m) and impedance f(z), was also investigated in single crystals and ceramics. The ratio r = f(m)/f(z) was found to decrease with increasing temperature and decreasing dopant concentration in all compounds. A sharp peak of r was detected in the vicinity of the phase transition region in scandium stabilized zirconia. A simple interpretation, based on the behaviour of a conductive system with a variable distribution of relaxation times, was proposed to explain the observed phenomena. (C) 2015 Elsevier B.V. All rights reserved.