NSF/DMR-BSF: Understanding Electro-Chemo-Mechanical Processes at the Atomic Level

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NON-TECHNICAL DESCRIPTION: Materials with strong mechanical response to applied electric fields hold great importance for a wide range of vitally important technologies ranging from focusing devices in the cameras of cellular phones to fuel injectors in automobiles. The discovery of the so called "chemical expansion effect" in selected ceramic materials, in which changes in chemical composition may cause the volume change and, hence, large stress, opened a possibility to elicit an electro-chemo-mechanical (ECM) response using electrical current to control chemical composition. The main challenges towards rationally designing new materials with the desired ECM response has been the inability of current materials to operate reasonably fast at room temperature and the lack of atomic-level understanding of their working mechanisms. The investigators are developing a new concept of an ECM material, based on the metal-ceramic nanocrystalline composites, that they had successfully tested for feasibility. To study the underlying principles of how they work, the researchers are using X-ray absorption spectroscopy, a research technique that uses ultrabright X-rays to identify changes in the local atomic environment around metal ions under operating conditions. The project impacts the field of ceramic materials through the development of fundamental understanding and design criteria for this new class of ECM materials. The project fosters international ties between Stony Brook University and Weizmann Institute of Science, Israel. The broader impacts of this project are being realized through connections between faculty and students from both institutions, mentoring of undergraduate and graduate students, and post-doctoral scholars in science and engineering disciplines, dissemination of research results to the peer community, and through exploration of materials for new technologies.TECHNICAL DETAILS: The focus of this project is to develop fundamental understanding of processes taken place in ceramic materials during electro-chemo-mechanical (ECM) actuation, an effect recently proposed for developing new generation of micro- and nano-actuators. The ECM effect is the change in mechanical dimensions of a solid as a result of a change in chemical composition induced by an electric field. To formulate the conditions for practical realization of ECM actuation, the complex relationship between the processes of oxidation/reduction, diffusion, phase transformation and generation of macro- and micro-stresses must be understood. As a platform for such investigation, Anatoly Frenkel (Stony Brook University), his international collaborator Igor Lubomirsky (Weizmann Institute of Science) and their respective groups are studying an oxygen ion transport-based ECM device using metal-ceramic nanocomposites. Atomic-level synchrotron characterization provides insights into the effects of the reduction, oxidation and strain in real-time operating conditions. This project offers research opportunities and training at advanced national research facilities at the post-graduate, graduate, and undergraduate levels. The project impacts the field of ceramic materials due to the development of fundamental understanding and material selection rules for the new class of ceramic-based ECM actuation materials.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.