Stroboscopic <i>in situ</i> neutron diffraction approach to elucidate the kinetics of strain mechanisms in ferroelectric materials

The electromechanical properties of ferroelectrics are often strongly frequency-dependent, but the underlying structural kinetics are not well known or understood. Here, we use in situ stroboscopic neutron diffraction combined with a comprehensive structural refinement method to examine the frequency-dependent structural change in the commercial actuator material PIC 151 at realistic operating frequencies. A broad range of frequencies was measured and analyzed in detail. This work further underlines the crucial role of the field-induced phase transformation for explaining the kinetics in ferroelectric materials. Both the tetragonal majority phase and the rhombohedral minority phase contribute with different effects to the frequency dependence of the strain mechanisms. Even creep effects well beyond the probed frequencies can be explained with the observations.