Electromechanical properties of SBN/BTN Aurivillius-type ceramics up to the transition temperature

An increasing interest on ceramics with Aurivillius-type structure has developed during recent years due to their high ferro-paraelectric transition temperatures, which make them good candidates for use as high temperature piezoelectrics. However, there are not many works in the literature that study the evolution of their piezoelectric activity with temperature. An automatic iterative procedure has been used in this work to characterise the piezoelectric, mechanical and dielectric properties at resonance of the (SrBi2Nb2O9)1−x(Bi3TiNbO9)x solid solution, with x=0.35 and 0.65, from room temperature up to the ferro-paraelectric phase transition temperatures, at Tc=580 and 790 °C respectively. In order to study the influence of the microstructure on the properties, sintered and re-crystallized after hot pressing ceramics were prepared. Mechanochemically activated precursors were used to prepare the ceramics with moderate processing temperature and time. Re-crystallization was successfully tested to obtain a range of microstructures with low porosity and variable grain size. In general, it is observed that low porosity and large grain size enhances the piezoelectric properties. Ceramics with x=0.65 present piezoelectric activity at temperatures as high as 500 °C, with kp=2.9%.