In situ Transmission Electron Microscopy Studies of Electric-field-induced Phenomena in Ferroelectrics

High electric fields were delivered to specimens during imaging in the transmission electron microscopy (TEM) chamber to reveal details of electric field-induced phenomena in ferroelectric oxides. These include the polarization switching in nanometer-sized ferroelectric domains and the grain boundary cavitation in a commercial lead zirconate titanate (PZT) polycrystalline ceramic, the domain wall fracture in a Pb(Mg_1/3Nb_2/3)O₃–PbTiO₃ single crystal, and the transformation of incommensurate modulations in Pb_0.99Nb_0.02[(Zr_1−xSn_x)_1−yTi_y]_0.98O₃ (PZST100x/100y/2) polycrystalline ceramics. In the PZT ceramic, a cavitation process was uncovered for the electric field-induced intergranular fracture. In the ferroelectric single crystal, a preexisting crack was observed to deflect and to follow a 90° domain wall, indicating the presence of severe incompatible piezoelectric strains at thedomain wall. In the antiferroelectric PZST ceramics, the electric field-induced antiferroelectric-to-ferroelectric phase transformation was accompanied with the disappearance of incommensurate modulations.