| Abstract Scope |
Functional properties of electroceramics are conventionally designed by adjusting the material's chemical composition. However, the ceramic microstructure offers alternative “tools” for property engineering, which enable enhanced performance or even new functionalities. Here, we show how extended defects can be utilized to enhance the piezoelectric response. The effects are based on the electrostatic and elastic interactions between the extended defects and ferroelectric domain walls. To this end, dislocations were introduced into BaTiO3 by mechanical deformation and were shown to pin the domain walls at low fields, resulting in piezoelectric hardening, while they imposed a macroscopic restoring force at high fields, increasing the piezoelectric coefficient (100pm/V to 2470pm/V). In another example, second-phase precipitates were introduced into (Ba,Ca)TiO3 and (Li,Na)NbO3 by a solution-precipitation heat treatment, akin to precipitation hardening in metals. The different geometries of the precipitates will be presented, along with means for their orientation and their influence on the electromechanical properties. |