The family of compounds that exhibit ferroelectric properties contains exciting materials that are enabling current and future generation wireless communications, information storage in consumer electronics, etc. This class of materials is inspiring exciting new strategies for catalysis, hybrid sensors, and as the basis of novel nanofabrication routes. Recent results have shown that the reactivity of these surfaces depends upon the orientation ferroelectric domains. Exploiting this and the future potential of ferroelectric materials requires that the atomic interactions at ferroelectric surfaces be understood. This project is using atomic-resolution probes to study molecular interactions at ferroelectric surfaces. In conjunction with this, a study of on gender equity in engineering is being undertaken.
TECHNICAL DETAILS: This program uses advanced scanning probe microscopy in conjunction with surface scattering and spectroscopic tools to determine the origin of surface structures on non-metallic perovskite oxides, specifically ferroelectrics, and the effect of local polarization on surface behavior. The interplay of atomic polarization and surface structure/reactivity is becoming critical in electronic devices such as those enabling wireless communications as components become smaller. It has recently been shown that ferroelectric domains exhibit domain specific surface reactivity. This has led to new concepts for nanofabrication, catalysis, and electronic devices. In order to develop a fundamental understanding of domain specific behavior, the structures of BaTiO3 (100) surfaces will be determined and the effect of domain orientation on adsorption will be quantified. In addition to training students on advanced atomic imaging in the context of important technological materials, a study on gender equity in engineering is being carried out.
Dawn Bonnell The University of Pennsylvania Ferroelectric compounds have been used in traditional oxide electronics for nearly 50 years. The last decade has seen the development of exciting new ferroelectric materials with applications in consumer electronics, medical diagnostic devices and sports equipment. New ideas have emerged for transformative applications in future computer processors, water splitting, light harvesting and industrial chemical catalysis. In order to realized these opportunities we must understand the atomic structure and local properties of new families of ferroelectric. This project determined the atomic and electronic structures of the surfaces of a BaTiO3 single crystal which serves as a platform on which to investigate the relation between structure and properties on ferroelectric surfaces in general. Following our earlier work in which a variety of chemical reactions on ferroelectric surfaces were investigated, this project achieved atomic spatial resolution using scanning tunneling microscopy and acquired spectra of the local electronic structure. By comparisons with theory, the positions of atoms at the surfaces could be determined and related to chemical reactions. A unique aspect of ferroelectric compounds is that they contain domains of aligned electric dipoles that terminate at a surface with a charge. These domains can be used to control electronic structure and therefore local chemistry. Some of the new ferroelectric materials consist of various layers of very thin films. The interaction of the ferroelectric polarization in these films gives rise to complex spatial variations in properties. This project developed a methodology to measure nanometer sized domains in very thin films which was demonstrated by determining that a macroscopic electric field exists within the films.. something that could not be determined with other methods. The project also focused on impacting the role of women in science and engineering with several activities. In Feb 2011 two workshops were held on the topic of 'Strategic Interactions and Negotiation'. One workshop was attended by 24 female graduate students and post docs in engineering and physical science; the second was attended by female undergraduate engineering students. Lee Warren and Nancy Houfek from Harvard University facilitated this interactive experience that used participants' experiences to demonstrate strategies for effective communication, professional interactions and conflict resolution. During the summers of 2009, 2010, 2011, and 2012 a summer academy on Nanotechnology was held for high school students on the Penn Campus. The enrollment was 30-40% female and three female graduate students developed and taught the course. In addition to providing clear role models for the high school students, the graduate student teachers had an opportunity to develop advanced education, communication, and management skills.
