This study is concerned with the microstructure of the tetragonal phase PZT in which the tetragonality depends on the ratio of $ZrO_2$ to $TiO_2$. The variation of tetragonality is related to the formation of 90$^\circ$ domain pattern which will affect the physical properties of PZT ceramics. The aging effects, dielectric and piezoelectric properties are measured for each composition. The microstructure and the X-ray intensity ratio $I_{(200)}/I_{(002)}$ are studied with the SEM and XRD.
With increasing the tetragonality, the 90˚ domain pattern shows the arrangement properties and by this properties the internal stress is relieved.
It is observed that the domain pattern of the surface is different from the internal part. When poling, the quantity of microcracks is increased with increasing the tetragonality.
And the presence of microcracks causes to reduce the relative dielectric constant.
The aging rate is determined by the interaction of the internal stress and the 90˚ domain mobility.
