Ferroelectric thin films of BaxSr1−xTiO3 with compositional gradients normal to the growth surface have been formed by the successive deposition and annealing of films having step-variable Ba to Sr ratios. By suitably tailoring the magnitude and sense of the gradient in Ba to Sr ratio, directional potentials can be built into the structures yielding a new, but controllable, hysteresis phenomenon. Slater’s empirical model for ferroelectric materials has been extended to also describe thin films with polarization gradients normal to the growth surface, i.e., graded ferroelectric devices. This model accounts for several aspects of these structures, including: the broadness of the permittivity plots with temperature, the formation of a spontaneous potential upon oscillatory field excitation, offsets in the hysteresis graphs along the displacement axis with directions which are gradient dependent, and the electric field dependence of that offset.

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Effective pyroelectric coefficients as large as 5 μC/cm2 °C, with peak responsivities at approximately 50 °C, were obtained from compositionally graded barium strontium titanate ferroelectric thin film devices formed on silicon using unbalanced magnetron sputter deposition. These effective pyroelectric coefficients are nearly two orders of magnitude larger than those observed from conventional pyroelectric thin film ferroelectric detectors.

LaMnO3 films doped with Ca, Ba, or Sr have been fabricated using the metalorganic decomposition technique. These films exhibit paramagnetic-to-ferromagnetic phase transitions at 250, 300, and 350 K, respectively. By measuring the film magnetization as a function of field and temperature we have determined the entropy change associated with these transitions. The large magnetization of these materials results in a total entropy change a factor of five less than that of gadolinium, the prototypical high-temperature magnetocaloric material. Improvements in film morphology and composition may provide a further increase in the magnetization and total entropy change in these materials.

High-frequency (1 MHz–1 GHz) transmission line measurements were used to determine the composition and frequency-dependent complex permittivities and complex permeabilities of ferroelectric/ferrimagnetic (barium titanate and a magnesium-copper-zinc ferrite) composites. The effective medium rules of Maxwell–Garnett give both lower and upper bounds for the effective permittivities and permeabilities and yield accurate estimates of the bulk electric and magnetic properties at low volume fill fraction of either component provided the proper host matrix is chosen. Bruggeman theory yielded the best predictive values for the permittivity and permeability over the entire composition range. In all cases these complex quantities were shown to be constrained by Bergman–Milton bounds.