Secondary phase softening effect in PZT-based ceramics by introducing the random electric fields

In this work, the random electric fields are constructed in the hard PZT ceramics by adding the ZnO particles as a secondary phase to tune the piezoelectric properties and losses. It is found that the internal bias electric field existing in the hard PZT ceramics has been tuned successfully by the random electric fields and its value reduces with the increased ZnO content. As a consequence, the piezoelectric constant d(33) reaches up to 483 pC/N in the PZT/0.75 wt%ZnO composite, which is much higher than that of the hard PZT matrix. In the meantime, the electromechanical quality factor Q(m), dielectric loss tan delta, and Curie temperature T-C for this composite are about 1109, 0.55%, and 279 degrees C, respectively. The promoted d(33) is attributed to the small domain size and reduced internal bias electric field, whereas the low losses (large Q(m) and low tan delta) can be put down to the still existing nonzero internal bias electric field.