Key Issues in the Characterization of Porous PZT based Ceramics with Morphotropic Phase Boundary Composition

Abstract

An iterative automatic method is used to calculate, from impedance measurements at resonance in three sample shapes and four modes of resonance, all the directly obtained coefficients that are needed to determine the ten elastic, dielectric and piezoelectric complex coefficients of the characteristic matrix of a 6mm symmetry ferro-piezoelectric ceramic for a controlled porosity material. A soft PZT ceramic with a Morphotropic Phase Boundary (MPB) composition was studied. Samples with homogeneously distributed close porosity were prepared and tested. A fugitive phase was added to the perovskite type structure precursor powder to produce the porous materials and the samples were consolidated by die pressing. Shear coefficients are here obtained using an alternative geometry to the Standards shear sample, that was proved to be dynamically clamped at resonance. Comparison of these shear results and those obtained with the geometry of the Standards is here discussed and the advantages for the shear characterization of porous ceramics derived from the use of this new geometry are presented.