Micromechanics of domain switching in rhombohedral PZT ceramics

The lattice strain ɛ{2 0 0} and diffraction peak intensity ratio R{1 1 1} have been determined in soft rhombohedral PZT ceramics during the application of an electric field up to 2.5 MV m−1 and as a function of the grain orientation ψ, using high energy synchtron X-ray diffraction. The magnitude of both ɛ{2 0 0} and R{1 1 1} increased sharply beyond a field level of 1 MV m−1 due to the onset of ferroelectric domain switching. ɛ{2 0 0} exhibited a near linear dependence on cos2 ψ, in agreement with previous studies of the remanent-poled state. In contrast, the R{1 1 1}–cos2 ψ plot showed evidence of saturation in ferroelectric domain switching, particularly for ψ > 60°. The development of lattice strain during poling is discussed in terms of contributions from the intrinsic piezoelectric effect and from residual stress caused by differences in the poling strain of a grain, and the piezoelectric strain of a grain relative to its surroundings.