Change of the weak-field properties of Pb(ZrTi)O₃ piezoceramics with compressive uniaxial stresses and its links to the effect of dopants on the stability of the polarizations in the materials

The properties of several Pb(ZrTi)O₃ (PZT) piezoceramics under compressive uniaxial stresses were characterized. It was observed that uniaxial stresses have a marked effect on the soft PZT materials, including reducing the piezoelectric coefficients and depoling the samples at relatively low stress levels. The effect of the uniaxial stresses on the properties of hard PZT's is more complicated because the domain structure of the materials can be changed substantially without depoling the samples. Therefore, under a compressive stress along the poling direction, the piezoelectric and electromechanical coupling factor can be increased markedly due to both the increased non-180° domain boundary motions and the deaging effect. In addition, the experimental results support the notion that the difference between a hard PZT and a soft PZT lies in the types of defects introduced by dopants. Immobile defects create frustrations in the lattice and result in a soft behavior, and mobile defects stabilize the polarization and produce a hard behavior.