Dielectric and piezoelectric properties of PZT ceramics with anisotropic porosity

Pb(Zr,Ti)O3 ceramics with homogenous, anisotropic porosity were manufactured and the influence of the anisotropic porosity on the dielectric and piezoelectric properties was studied. Image analysis allowed the quantification of the preferential orientation and the calculation of the distribution of the aspect ratio of the pores. The different dependence of the permittivities on the porosity content demonstrates that the population of pores is constituted of a high volume of pores with low aspect ratio and a low volume of pores with high aspect ratio. In view of the quantitative results obtained on the microstructure, an explanation of the frequency dependence of the dielectric and piezoelectric behaviour is suggested. Furthermore, the higher d31 piezoelectric coefficient in the material with anisotropic pores than in material with isotropic pores is related to higher effective fields which are a consequence of the enhanced longitudinal mobility of the material under transverse stress.