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Structure and Reactivity of Ferroelectric Surfaces: BaTiO 3 (100) Dawn A. Bonnell, University of Pennsylvania, DMR 0805174 The orientation of ferroelectric.

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Presentation on theme: "Structure and Reactivity of Ferroelectric Surfaces: BaTiO 3 (100) Dawn A. Bonnell, University of Pennsylvania, DMR 0805174 The orientation of ferroelectric."— Presentation transcript:

1 Structure and Reactivity of Ferroelectric Surfaces: BaTiO 3 (100) Dawn A. Bonnell, University of Pennsylvania, DMR 0805174 The orientation of ferroelectric domains affects both chemical reactions at surfaces in liquids and molecular adsorption from vapor and in the origin of novel device fabrication strategies as well an new approaches to catalysis. In order to probe the atomistic processes that underlie the orientation dependence of these interactions, scanning tunneling microscopy was used to image the structure of BaTiO3 (100) surfaces, orient domains in a controlled environment, compare tunneling spectroscopy before and after exposure to CO2. The difference map shows that the positively poled domain exhibits a higher current than the unpoled surface. This is also evident in the tunneling spectra in which a 1-2 order of magnitude difference in current is observed at all biases. The negative bias offset on the unpoled surface is due to band bending, which is not present in the positively poled domain. This confirms the effect of domain orientation on surface electronic structure. BaTiO 3 (100) R5xR5 Difference map of STM current before and after poling a c+ domain poled unpoled

2 Summer Academy in Nanotechnology for High School Students Dawn A. Bonnell, University of Pennsylvania, DMR 0805174 In summer 2009 D. Bonnell coordinated a course for high school students on Nanotechnology. The 3 week course is part of a residential Summer Academy for Applied Science and Technology sponsored by the School of Engineering and Applied Science. The course was taught by Laura Kraya and Esther Yu graduate students of MSE and BE, respectively. In addition to lecturing, they led students in hands-on labs experiences in liquid crystals, fabrication, nanoparticles, LEDs and electron microscopy, as well as structured debates on topics in biomedical ethics and tours of the Franklin Institute. Student surveys indicated that the impact of the nanotechnology course was an increase in: the number of science/engineering courses the students intend to take in college, the number that intend to major in science and engineering degrees, and the number that hope to become scientists.

3 Enter Your Highlight Title Here Dawn A. Bonnell, University of Pennsylvania, DMR 0805174 Professor Ruth Schwartz-Cohen is carrying out research for a book about the history of American women engineers. The focal research question has been, “Why are there so few women engineers?” As part of the data collection, a series of teas were held inn April 2009 at which women engineers discussed their histories, perceived challenges, and bases for success. Separate sessions were held for faculty members both tenured and not yet tenured, graduate students and post docs. The analysis of these sessions resulted in a revision of hypothesis and will be followed up with a series of individual interview sessions.


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