Further Experiments on the Sidewise Motion of 180° Domain Walls in BaTiO3

Techniques have been developed to extend the measured electric field dependence of the sidewise 180° domain-wall velocity in liquid-electroded BaTi${\mathrm{O}}_3$ crystals. The wall velocity data now cover about eight decades of velocity. The wall velocity is given by $v_{\infty }\exp (-\frac{\delta }{E})$, where $\delta$ is found to increase slightly with field. The temperature dependence of $v$ has been measured over a limited temperature range and the data show that $\delta$ varies with temperature faster than $T^{-1\mathrm{}}$. The shapes and orientations of the reversed domains are field dependent. As the electric field is increased, the approximately square reversed domains observed in the low-field region go over into octagonal domains. At still higher fields, approximately square domains rotated by 45° about the ferroelectric axis with respect to the low-field domains are observed. Several of the important features of the sidewise wall motion are consistent with a nucleation-controlled model which is currently under investigation.