Domain formation and domain wall motions in ferroelectric BaTiO sub 3 Single Crystals.

Using very good BaTiO3 single crystals, we have investigated the arrangements and movements of the domains. Besides the well known 90° walls we have observed 180° walls very clearly. A 180° wall forms the boundary between two domains polarized at 180° to each other (antiparallel). It turns out, that every so called single domain crystal consists of hundreds of small antiparallel domains, Applying and changing an electric field very slowly, we watched the change of the domain pattern and the behavior of the hysteresis loop at the same time (using a d.c. amplifier for the scope). With this method we have obtained a much better understanding of the creation of domain walls and their motion and also of the quite remarkable shape of the hysteresis loop.