Interaction between the domain boundaries and regions of the phases of different symmetry in the grains of the PZT type piezoceramics

The tetragonal (T) and rhombohedral (R) ferroelectric phases are known to coexist in PZT type piezoceramics. Different forms of the phase coexistence in the ceramics grains are discussed. The interaction of the domain walls with the T phase regions in the R grains and the R phase regions in the T grains is considered. It is found that the 180° domain walls in the T (or R) grains can pass sufficiently freely through the R (or T) regions existing in these grains. The behavior of the domain walls of other types is different; and passing of these walls through such regions is more difficult. However it does not mean that they can not pass.