Microstructural engineering of ferroelectric and electromechanical properties in 0.65KBT-0.35BCZT ceramics

The influence of processing procedures and microstructural features on the functional properties of relaxor ferroelectric ceramics are of fundamental interest and directly relevant to their applications in dielectric capacitors and electro-mechanical sensors/actuators. In the present work, solid solu-tions of 0.65(K0.5Bi0.5)TiO3-0.35(Ba0.94Ca0.06)(Ti0.93Zr0.07)O3 (0.65KBT-0.35BCZT) were processed by solid state reaction using 2 different procedures, distinguished in terms of mixed or separate calcination of the KBT and BCZT components and leading to homogeneous or core-shell type relaxor ferroelectric ceramics respectively. Systematic research was conducted on the impact of the processing techniques and air-quenching procedures on the structure, ferroelectric, and electromechanical properties. Higher remanent polarisation of the separately calcined materials was ascribed to the ferroelectric nature of the core regions, along with the non-ergodic relaxor ferroelectric re-sponse in the shell, which was enhanced by the quenching process. It was also demonstrated that the thermal depolarisation temperature increased significantly after quenching, from ~100 to ~160 °C for the separately calcined ceramic and from ~50 to ~130 °C for the mixed material; these effects are linked to notable improvements in the ferroelectric tetragonal phase content by air-quenching.