Processing and characterization of high Q(m) ferroelectric ceramics

Use of ferroelectric ceramics in applications like piezoelectric transformers was made possible by the development of new materials with high electromechanical coupling coefficients and high mechanical quality factor. `Hard'' ferroelectric ceramics of complex composition based on lead zirconate titanate with Nb, Mg, Mn and Li additives have been prepared. The perovskitic phase was produced by solid phase reaction of the oxides. The crucial role played by the intermediate mixing and grinding procedures in the assessment of the final properties of the material was investigated. Densification up to approximately the theoretical density value was achieved. The polarization was obtained by subjecting the samples at 30 kV cm(-1) poling electric field, in a silicon oil bath heated at 120 degrees C. Their structural and morphological properties were checked by X-ray diffraction analysis and scanning electron microscopy. Ferroelectric and piezoelectric properties were determined in agreement with IEEE measurement standards. The optimized samples presented very high quality and electromechanical coupling factors, together with small dielectric loss. (C) 1999 Elsevier Science Limited. All rights reserved.