The objective of this Faculty Early Career Development (CAREER) Program award is to gain fundamental understanding of the flexoelectric effect (polarization induced by inhomogeneous strain) in single-crystalline ferroelectric nanowires (NWs). The theoretical prediction of a gigantic flexoelectric enhancement of the polarization on the nanometer scale will also be tested. If true, it would make possible highly efficient nanogenerators for nanoscale mechanical energy harvesting. The research will focus mainly on BaTiO3 NWs because bulk polycrystalline BaTiO3 has the highest reported flexoelectric coefficient. Other perovskite ferroelectric NWs, such as PbTiO3 and Pb(ZrxTi1-x)O3 (PZT), will also be studied to reveal the cation contribution to flexoelectricity. The bulk of the research is to use these well-characterized NWs as a basis for state-of-the-art scanning probe microscopy studies, which will quantify the intrinsic flexoelectric coefficients and testing the prediction of flexoelectric enhancement and establish the phase and domain contributions to the flexoelectric effect. In addition, supported by experimental measurements, the nanoscale intrinsic flexoelectric coefficients and the mechanical-to-electric energy conversion efficiencies will be theoretically predicted.
This research will provide an in-depth, experimentally grounded understanding of the flexoelectric effect at the nanometer scale, which is expected to generate transformative knowledge for directing the design of nanogenerators with dramatically improved mechanical-to-electric energy conversion capability and, more generally, will establish a materials science basis for reduction in size and enhancement in performance of conventional piezoelectric and ferroelectric devices. This project will be integrated into university-wide programs to reach out to high-school students and K-12 teachers and attract students from underrepresented minorities (URM) to science, technology, engineering, and mathematics disciplines. A long-term stepwise education program will be established for instructing, mentoring, and training URM students from high school students, to college freshmen, to senior undergraduate students. This effort aims at improving the diversity of students at UW-Madison. Collaboration with the campus Research Experience for Teachers program will allow us to outreach to high school teachers who are interested in advanced nanoscience and nanotechnology and to help them create or improve science courses in their own schools. A set of comprehensive lecture notes for nanotechnology education based on the PI's new nanotechnology course will be developed and distributed online.
