Nanostructured ferroelectrics are envisioned to possess novel and superior functional properties, yet the apparent existence of a size limit under which perovskites lose ferroelectricity severely limits the development of ferroelectric nanostructures. To overcome the difficulty, this project seeks to develop novel ferroelectric polymer based nanocomposite films using Langmuir-Blodgett (LB) deposition. The multilayer composite films will be built up by alternating at nanoscale the ferroelectric polymer films with other dielectric or ferroelectric layers made by various methods including standard solvent-deposition and nanoparticle dispersion techniques. The in-plane nanostructures will be constructed based on the formation of positive and negative nanomesa templates in LB films, with nanoparticles screen printed onto the substrate between the nanomesas or in the nanoholes. As such, ferroelectric nanocomposite films with one-, two- and three-dimensional heterogeneity will be fabricated. The fabrication will be tightly coupled with our modeling effort, where the microstructure evolution in ferroelectric nanocomposites will be simulated by energy-minimization approach and phase field theory, and their macroscopic properties will be analyzed by micromechanics models. The modeling of structure-property relationship will lead to an optimization scheme for a series of functional properties, including electrostriction and piezoelectric effect, pyroelectric coefficients, and dielectric tunability, which will be applied to guide the processing and fabrication of nanostructured ferroelectric devices.
The knowledge derived from this research will enable the design and optimization of ferroelectric polymer based nanocomposite films possessing novel and unique functional properties, with direct impact on the manufacturing of nanostructured ferroelectric devices such as microsensors and microactuators, infrared detectors and microwave devices. The project will provide the opportunity to two graduate students to get involved in the interdisciplinary research dealing with the modeling, fabrication, and characterization of nanostructured ferroelectric polymer films. It will also draw undergraduates into science and engineering via the unique interaction between design, manufacturing, and characterization of ferroelectric nanocomposites through the Undergraduate Creative Activities & Research Experiences program (UCARE) at University of Nebraska-Lincoln. Results from this research will be incroporated in the content of an active materials course developed by the PI, which currently addreses only bulk ferroelectric behavior. Interactive, web-based tutorials and database will also be devoped to ensure broad dissemination of our scientific and technological finding.
