SPACE-CHARGE RELAXATION IN PEROVSKITES

We report a dielectric anomaly in several perovskites at intermediate frequencies 10 less-than-or-equal-to f less-than-or-equal-to 10(7) Hz in the temperature range 400-degrees-C less-than-or-equal-to T less-than-or-equal-to 800-degrees-C. We have found this dielectric maximum in more than 100 samples of various shapes and textures. This anomaly is shown to arise from a Debye dielectric dispersion that slows down following an Arrhenius law. We have established a link between this dielectric relaxation and the conductivity. We propose that it can be achieved through a space-charge model that quantitatively agrees with the experimental results in the lower temperature range.