Microstructural Features and Functional Properties of Bilayered BaTiO₃/BaTi_1−xZr_xO₃ Ceramics

Abstract

Validity of mixture rule for dielectrics in series configuration and the correlation between microstructure and electrical properties in bilayered BaTiO 3 /BaTi 1-x Zr x O 3 ceramics were studied. Samples were obtained from BaTi 1-x Zr x O 3 (BTZx) nanopowder synthesized by the polymeric precursor technique and had their microstructure, dielectric, piezoelectric and ferroelectric properties investigated.These bilayered ceramics properties were compared to the properties of homogeneous BTZx samples. And, also, the former's electrical permittivities were compared with the predictions of the simple mixture rule. According to the results, the microstructures of the layers do not differ from the microstructure of the corresponding homogeneous BTZx ceramic. And pyroelectric coefficient measurements show that the electrical properties of the interface do not contribute to the functional properties of the bilayered samples. Nevertheless, on increasing Zr 4+ , the agreement between the experimental and the predicted permittivity of the 1 thimaral@ursa.ifsc.usp.br 2 bilayered ceramics is gradually reduced, mainly at temperatures where the permittivity is governed by the response of the layer containing Zr 4+ . As a mechanical joint between the layers, the interface induces stresses during sintering due to thermal mismatch between compositions, thereby affecting the bilayer's electrical properties. Our results show that mechanical interface effects compromise the functional properties of layered ferroelectric ceramics.