(Bi3TiNbO9)(x)(SrBi2Nb2O9)(1-x) Aurivillius type structure piezoelectric ceramics obtained from mechanochemically activated oxides

Ferroelectric ceramics of (Bi3TiNbO9)(x) (SrBi2Nb2O9)(1-x) compositions are proposed in this work for use as high temperature piezoelectrics. Novel co mpositions with x > 0.40 have been processed and studied. This type of comp ound grows in lamellar crystals, resembling their layered Aurivillius type structure, with the perovskite e-axis perpendicular to the major surfaces, which tend to pile up with the c-axis parallel to the applied pressure when ceramics are obtained by hot pressing. Such texture does not favor the fer ro-piezoelectric properties. Isotropic ceramics with low porosity were proc essed by natural sintering of a mechanochemically activated oxide mixture. Optical microscopy and computer-aided image analysis and measurements were used in the characterization of the ceramic microstructure. Ceramics with t ransition temperatures in the range of 420 degrees C less than or similar t o T-t less than or similar to 900 degrees C can be obtained. Ferro-piezoele ctric characterization shows that ceramics with x = 0.60 present T-t = 700 degrees C, d(33) = 11 PC N-1 and K-t = 9.45%, which make them good candidat es to be tested as high temperature piezoelectrics. (C) 2000 Acta Metallurg ica Inc. Published by Elsevier Science Ltd. All rights reserved.