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

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. (C) 2003 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.