Anomalous low-frequency dispersion in X/sub 2/BaCuO/sub 5/ compounds

Abstract

We present and discuss the anomalous low-frequency dispersion process observed in perovskite ceramics (X/sub 2/BaCuO/sub 5/, X=Eu-La-Y). The interpretation is given in terms of the Dissado-Hill-Jonscher theory. It is based on a cluster description of the structural ordering and fluctuation in carrier-dominated dielectrics. It is shown that this form of response occurs for systems of low spatial dimensionality and generates a sample-size-dependent conductivity. The relationship of the mechanism to that of power-law noise in electrical systems is identified and its structural interpretation explored. Particular features of several ceramics related to superconductors compounds are described.