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Crystal Symmetry Dependent Deformation in Pb(ZrxTi1-x)O3 Ceramics



Ferroelectric ceramics had been widely used as sensors, actuators, transducers, etc., due to their peculiar electromechanical coupling properties, ultrafast response and compact size. Among all the ferroelectric ceramics, lead titanate zirconate (PZT) family ceramics got the most widely applications and were systematically studied for years. PZT ceramics will show linear piezoelectric behavior under a low electric field or a small stress, while exhibit intensively nonlinearities when subjected to a large electric field or a high stress which is thought to be caused by domain switching. Domain switching in ferroelectric ceramics is crystal symmetry related. There exists only 1800 and 900 domain switching in tetragonal ceramics, and 1800, 1090 and 710 switching in rhombohedral ceramics. In ferroelectric single crystals, perfect alignment of polarization can be achieved and a single domain state can exist after poling by a strong DC field. While this is not the case in ferroelectric ceramics where the crystallite axes arrange in a random way and multiple domain states could exist after poling. In a real ferroelectric ceramics, domain switching will be constrained by neighboring domains and may not accomplish completely even a very large electric field is applied. The constraint level of domain switching in ferroelectric ceramics is also crystal symmetry dependent and it may be well known that tetragonal PZT ceramics is difficult to pole, while rhombohedral PZT and PZT ceramics near the morphotropic phase boundary (MPB) are easier to.

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