  Epitaxial thin films of relaxor PbMg1/3Nb2/3O3 and PbSc0.5Nb0.5O3, and
ferroelectric PbZr0.65Ti0.35O3, Pb0.955La0.045Zr0.65Ti0.35O3, and
Ba0.4Sr0.6TiO3 were prepared, and their dielectric properties were studied in a
broad range of the measurement conditions. In the ferroelectric state, the
presence and the change of configuration of the domains determined both the
dynamic dielectric nonlinearity and the polarization hysteresis. In thin-film
relaxors, the orientation of the randomly interacting dipoles in a random field
was responsible for the dynamic dielectric nonlinearity, while the observed
hysteresis was suggested to arise due to connection between the applied field
and the relaxation times of both the dipoles and the internal field. In
thin-film (Ba,Sr)TiO3, the high-temperature dielectric hysteresis was found to
be relaxorlike.
