Improvement by recrystallisation of Aurivillius-type structure piezoceramics from mechanically activated precursors Original Research Article

To improve the texture and microstructure with the aim of getting proper mechanical stability and electromechanical properties, a combination of hot-pressing and subsequent thermal treatment of recrystallisation at higher temperature is proposed in this work for the processing of Aurivillius-type structure piezoceramics. Ceramics of (SrBi2Nb2O9)0.35 (Bi3TiNbO9)0.65 were prepared. The use of mechanically activated ceramic precursor powder allows obtaining isotropic ceramics in a single thermal treatment, in which synthesis, grain growth and sintering takes place simultaneously. A comparative study of the microstructure and the mechanical and electromechanical properties of the recrystallised, the parent hot-pressed and the ceramics naturally sintered at temperatures close to those used for the recrystallisation was carried out. Microstructures were quantitatively characterised by computer-assisted analysis of optical and scanning electron microscopy (SEM) micrographs. The influence of porosity and grain size on the mechanical properties is discussed.