Anisotropic piezoelectric effect in modified PbTiO(3) ceramics.

Experimental and theoretical investigations of the electromechanical anisotropy of ceramics modified with Ca, Ni-Nb, and Mn are presented. It is demonstrated that the large anisotropy of these ceramics is neither a bulk property of the PbTiO(3)-crystallites nor a domain wall effect. The anisotropy is caused by the statistical orientation of the crystallites in the ceramics and by the material properties due to this orientation. The ratio of electrostrictive coefficients and the ratio of single-crystal permittivities in these ceramics also play a decisive role. The result enables one to comprehend easily the dependence of the ceramic's electromechanical anisotropy on the material composition, the degree of poling, and the temperature.