TEM of antiferroelectric-ferroelectric phase boundary in (Pb_(1-x)Ba_x)(Zr_(1-x)Ti_x)O_3 solid solution

摘要

TEM and XRD have been used to characterise the antiferroelectric-ferroelectric phase boundary which exists in the (Pb_(1-x)Ba_x)(Zr_(1-x)Ti_x)O_3 solid solution close to the PbZrO_3 end member. Electron diffraction patterns and XRD spectra from the antiferroelectric phase could be indexed according to the PbZrO_3 structure with superlattice reflections typically present at the ± 1/4 {hk0} pseudocubic positions. By XRD, the polar ferroelectric phase appeared to be rhombohedral but electron diffraction patterns showed the presence of superlattice reflections at the 1/2{hk0} positions, indicating that the unit cell size was doubled with respect to the simple perovskite lattice. The intensity of these reflections was observed to decrease with increasing Ba and Ti concentration. A combination of dark field and high resolution dark field images showed the presence of antiphase boundaries associated with these reflections which were highly mobile during irradiation in the electron beam.