90° a-b domains in epitaxial ferroelectric Bi_(3.25)La_(0.75)Ti_(3)O_(12) films

摘要

A cross-sectional high-resolution electron microscopy study was performed on (010)/(100)-oriented ferroelectric Bi_(3.25)La_(0.75)Ti_(3)O_(12) (BLT) films. Using Bragg filtering, curved, irregular, and nanoscale 90° domain configurations were observed. The weak ferroelastic strain of 0.024% suggests a negligible polarization clamping of 90° a-b domains under bipolar electric field and an easy 90° switching of the polar a axis in the ab plane. In addition, antiphase boundaries were characterized. A negligible contribution of 90° a-b domains to the fatigue of BLT is proposed.