Regularly twinned domain structures are observed by scanning piezoforce microscopy on single crystalline grains of $\mathrm{Bi}\mathrm{Fe}{\mathrm{O}}_3$ ceramics being grown by a special low temperature sintering process. The domains are considerably larger than those observed in thin films. Their spontaneous polarization comes close to that predicted theoretically and overcomes restrictions hitherto being set to bulk single crystals. The observed ferroelastic twin domain structure resembles that of classic $T$ domains in rhombohedrally distorted NiO, but is additionally superimposed by ferroelectric twin domain patterns.

Dielectric relaxation and polar structures of BaTi1−xSnxO3 ceramics, x=0.10–0.20, are investigated by means of dielectric spectroscopy and piezoresponse force microscopy. A transition regime between “normal” ferroelectric and relaxor behaviors is encountered. In the compositions with x=0.10, a complex domain pattern confirming the ferroelectric state is observed. Strong dielectric relaxation around Tm is attributed to domain wall motion. On the other hand, the dielectric spectra in the sample with x=0.20 are very similar to those observed in relaxor ferroelectrics. Analysis of the relaxation spectra at the intermediate concentration, x=0.15, reveals both domain wall response and an additional contribution related to mesoscale polar structures. The appearance of relaxor behavior in BaTi1−xSnxO3 is discussed within the framework of the random field model.

High-resolution domain studies have been performed on $0.8\mathrm{Pb}\left({\mathrm{Mg}}_{1/3}{\mathrm{Nb}}_{2/3}\right){\mathrm{O}}_3-0.2\mathrm{}{\mathrm{PbTiO}}_3$ (0.8PMN-0.2PT) single crystals via piezoresponse force microscopy (PFM). A complex structure consisting of micron-size domains comprising embedded nanodomains of opposite orientation has been revealed on the (100) surface of the crystals. The existence of such peculiar patterns is related to the combination of ferroelectric and relaxor properties in this particular composition. The micron-size areas represent “normal” ferroelectric domains, while embedded nanodomains are attested to polar clusters that might exist in relaxors far above the Curie point ${(T}_C)$ and to be preserved below $T_C$ due to local random fields. The evolution of domain structure of 0.8PMN-0.2PT crystals is studied under increasing temperature.