Flexoelectric effect in ceramic lead zirconate titanate

Mechanical strain gradient generated electric polarization or flexoelectric effect was investigated in unpoled lead zirconate titanate (PZT) ceramics in the ferroelectric state by using a cantilevered beam based approach. Flexoelectric coefficient mu(12) at room temperature was measured to be 1.4 muC/m in the PZT ceramic at small level of strain gradient. Temperature-dependent experimental investigations clearly showed that high dielectric permittivity in the ferroelectrics enhanced flexoelectric polarization: essentially a linear relation was found to exist between mu(12) and dielectric susceptibility chi at lower permittivity level (2100-2800), while mu(12) versus chi curve started to deviate from the straight line at the chi similar to 2800 and nonlinear enhancement of mu(12) with chi was observed, with mu(12) value reaching 9.5 at chi similar to 11000. The nonlinearity in the flexoelectric effect was associated with domain-related processes. It is suggested that flexoelectric effect can have a significant impact on epitaxial ferroelectnic thin films and mesoscopic structures. (C) 2005 American Institute of Physics.