One dimensional ferroelectric nanowires have attracted much attention due to its interests in fundamental physics and potential applications in Nanoelectromechanical Systems (NEMS), non-volatile ferroelectric memories, and sensors. Domain structure is the most important property of ferroelectric materials determining their applications. Single crystalline BaTiO3 nanowires were synthesized with molten salt mediated solid state chemical reaction approach. Piezoresponse Force Microscopy (PFM) technique was developed and applied for the study of ferroelectric domain structure in the BaTiO3 nanowires. We further developed a new method especially for the study of ferroelectric property of nanowires with PFM, in which electric bias is directly applied along the axial direction of nanowire. Our studies revealed a highly stable, in plane (nanowire axial direction) single domain formation in the single crystalline BaTiO3 nanowires. With the assistance of nanomanipulation and focused ion beam (FIB) techniques, we fabricated a nanoscale energy converter device using an individual BaTiO3 nanowire. In this device, due to piezoelectric effect, periodic voltage generation was produced from the BaTiO3 nanowire by a periodically varying tensile mechanical strain applied with precision mechanical testing stage. The measured voltage generation from the nanowire was found to be directly proportional to the applied strain rate, and was successfully modeled through the consideration of an equivalent circuit for a piezoelectric nanowire under low frequency operation. This device, besides demonstrating a controlled experimental method for the study of direct piezoelectric effect in nanostructures, implies also the use of such perovskite piezoelectric nanowires for efficient energy harvesting applications.
Breezed and Uploaded by Cezary Wojtkowski
University of Illinois at Urbana-Champaign.