Piezoelectric ceramics can couple electrical and mechanical energy, enabling us to sense and interact with our environment in multiple ways. Examples of devices utilizing piezoelectric ceramics include diagnostic and therapeutic ultrasound, sonar, vibration and position sensing, large-displacement actuation, micro-technologies including micro-positioning, and renewable power generation or energy harvesting. Many of these applications often function under dynamic conditions and although material properties can currently be measured under these conditions, time-resolved structural characterization techniques do not yet exist that can characterize the structural state of materials as a function of time during dynamic loading. This program will develop time-resolved X-ray diffraction techniques using both local instrumentation and through access to international synchrotron diffraction facilities and apply these tools to develop a more fundamental understanding of the time-dependent structural behavior of piezoelectric ceramics. This program will lead to an entirely new way of reconciling macroscopic properties in terms of structural dynamics in the time and frequency domains and has application in numerous other material systems. In piezoelectric ceramics, this framework will promote the development of lead-free, high-temperature, and multiferroic sensors and actuators. A primary educational component of this program is the development of international partnerships and the provision of international research experiences for students. This program will enable students to perform hands-on research at top-tier research institutions in Europe. These experiences will foster an awareness and appreciation for diversity of cultural and educational background, experience, and intellectual approach. Another significant educational component of this proposal is the development of in-house instrumentation for time-resolved structural studies at the University of Florida. The development of in-house instrumentation in a multi-user facility will enhance regional infrastructure for research and education and promote the development and dissemination of next-generation instrumentation. Hands-on modules will be developed for the in-house instrumentation to help teach undergraduate ceramics laboratories, core and specialty undergraduate courses, and graduate courses. Versatile software tools for the systematic and consistent analysis of diffraction datasets will also be developed and disseminated.
TECHNICAL DETAILS: Materials scientists often describe the macroscopic behavior of materials in terms of microscopic origins through structure-property relationships. For macroscopic properties measured under dynamic perturbation, the development of such linkages is particularly difficult due to the lack of time-resolved structural characterization techniques. The primary goal of this program is to establish a new framework in which to investigate the relationship between structure and macroscopic properties of piezoelectric ceramics in the time domain. This will be accomplished by developing time-resolved stroboscopic data collection techniques during X-ray diffraction of bulk piezoelectric ceramics. The established framework will then be used to enhance the fundamental understanding of hysteresis, nonlinearity, and frequency dispersion in a variety of piezoelectric ceramic systems. For example, time-resolved techniques will enable a quantitative determination of the role of extrinsic mechanisms such as domain wall and interphase boundary motion on macroscopic properties. Ultimately, this will lead to an enhanced understanding of the origin of the macroscopic electromechanical behavior and its frequency and time dependence in polycrystalline piezoelectric ceramics. Throughout the course of the program, students will travel to the European Synchrotron Radiation Facility and the Ecole Polytechnique Federale de Lausanne to work with leading scientists while conducting high-energy X-ray diffraction experiments and complementary property measurements.