Nanoscale domain switchings of Bi_(3.15)Dy_(0.85)Ti_3O_(12) thin film under the simultaneous application of polarizing voltage and loading force

摘要

The nanoscale domain switchings of Bi_(3.15)Dy_(0.85)Ti_3O_(12) thin film annealed at 700℃ were observed by piezoresponse force microscopy under the different DC polarizing voltages, loading forces, and simultaneously both of them. Then, the formation mechanisms of domain switchings were analyzed from the perspective of dynamics of ferroelectric nanodomain and equilibrium state free energy of ferroelectric nanodomain. First, the 180° domain switchings were observed under the single polarizing voltages ±12 V. However, there are small amounts of anti-parallel domains. Second, the 90° domain switching was detected under the different single loading forces (150 and 300 nN). Finally, both 90° and 180° domain switchings were obtained under the simultaneously applied fields of polarizing voltage (+10 V) and loading forces (100 and 200 nN). The formation mechanisms of typical electric-generated nanoscale domain switchings were analyzed by forward domain-growth mechanism and grain deformation, and the abnormal electric-generated domain switching is interpreted by grain boundary effect and built-in electric field. Furthermore, we adopted the domain switching criterion from the perspective of equilibrium state free energy of ferroelectric nanodomain to uniformly explain the mechanisms of domain switchings induced by different external fields. It is necessary to understand the evolution mechanism of nanoscale domain switching for ferroelectric thin film devices.