COMPOSITION STRUCTURE-PROPERTY RELATIONS OF MULTI-ION-BEAM REACTIVE SPUTTERED LEAD LANTHANUM TITANATE THIN-FILMS .3. ELECTRICAL-PROPERTIES

This paper, the third and final of a three part series, presents the electrical properties of postdeposition annealed, lead lanthanum titanate (PLT) thin films deposited by multi-ion-beam reactive sputtering (MIBERS). Also, a model is presented that explains the relations among composition, crystallographic structure, microstructure, and electrical properties of the PLT thin films. Thin films of PLT consisting of the perovskite phase exhibit [100] textured microstructures. Addition of a critical quantity of excess PbO results in the loss of this [100] texture, and continuity of the perovskite phase is disrupted while both excess PbO and porosity phases become continuous due to a percolation effect. Films with textured microstructures consisting of a continuous perovskite phase exhibit relatively high dc resistivities, high dielectric permittivities, and high remanent polarizations. At the transition between textured, and nontextured microstructures, a discontinuous drop in the electrical properties occurs due to the ensuing continuity of the excess PbO and porosity. These composition-induced changes in the electrical properties were quantitatively modeled by applying a simple mixing rule model to the microstructure model developed in Part II of this series.