Dislocation mechanism of ferroelectric fatigue during multiple switching

Abstract

The paper is concerned with the characteristic features of the dislocation mechanism related to fatigue in ferroelectrics in the process of their repeated switching. In a polarized crystal, dislocations possess a charge the sign of which depends on the orientation of the spontaneous polarization vector relative to the dislocation line. In the process of hysteresis switching, the average force from the applied field acting on a charged dislocation for one period of the hysteresis loop is not equal to zero. Such long-acting force leads to the accumulation of defects near the surface, which can fix a polarization and so partially remove it from the switching process. The proposed mechanism explains the key dependences of the critical number of switching cycles on the field amplitude, frequency and temperature of the sample.