Electrical and mechanical properties of core-shell type structures in doped BaTiO/sub 3/

Abstract

Ferroelectric, core-shell type structures consisting of grains having a diffuse shell and a well defined ferroelectric core, have been developed. These materials were processed in such a way as to: (1) yield a gradient in dopant concentration through each grain, generating either a highly doped shell with a virtually dopant free core, or a uniformly modified grain interior; or, (2) generate a core-shell material, with a gradient from dielectric to semiconductor behavior through the material thickness. These type microstructures, derived from controlled isovalent (ZrO/sub 2/) and/or aliovalent (Y/sub 2/O/sub 3/, Nd/sub 2/O/sub 3/) doping of the base BaTiO/sub 3/ material, were investigated for use as sensors, high strain response materials and high permittivity capacitors. Characteristic of these materials is a stress gradient in the grain, controlled by dopant inhomogeneity, creating a clamping of either the dielectric, resistance or piezoelectric properties.