Abstract

The article presents a detailed study of the dielectric properties and conductivity of the SrTiO3 crystal in the temperature range 350 - 900 K in oxygen-free environment (Ar). The study has established that ionic conductivity that reaches a certain value is carried out by associated carriers. This is accompanied by a noticeable increase in the conductivity activation enthalpy Ha. The data are compared with those for LiNbO3:Zn, Mg crystals. Comparison unambiguously confirms the defects association at high values of ionic conductivity, at least for the case of oxygen-octahedral structures. We have found that the effect does not depend on the specific features of the crystal structure (perovskite in SrTiO3 or pseudoilmenite in LiNbO3). It also does not depend on the charge carrier type (O2− or Li+). We have found a temperature region in ionic conductors where both ionic associates and single carriers determine the character of ion transport. The upper temperature limit for the existence of associates (T**) is the temperature at which kT** > EC, where EC is the binding energy of the associate. At T > T**, the associates are destroyed and ionic conduction is again realized only by single carriers with a corresponding decrease in Ha.

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