Piezoelectric nonlinearity due to motion of 180° domain walls in ferroelectric materials at subcoercive fields:: A dynamic poling model

A mechanism is described whereby 180 degrees domain wall motion can contribute to the electrically induced strain in a ferroelectric material at subcoercive ac electric fields. The field-dependent, largely reversible motion of ferroelectric, 180 degrees domain walls due to an applied ac electric field is considered. The Rayleigh law is modified to describe the piezoelectric response of the system. This results in both a linear dependence of the piezoelectric coefficient on the amplitude of the applied electric field and the creation of a second order harmonic of strain which adds to the electrostrictive response. The model was experimentally confirmed in Pb(Zr1-xTix)O-3 thin films.