Materials World Network: Measurement of Local Charge Distributions in Materials

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This Materials World Network award to Northwestern University is for collaborative research to develop the experimental methodology and theoretical framework necessary to directly image charge distribution at the atomic level in a range of technologically important oxide materials. These materials are used extensively in catalysis; as new dielectric, ferroelectric and in some cases magnetic devices and in oxygen transport membranes and fuel-cells; they are also critical in many corrosion problems. Conventional measurements of charge are carried out with blunt instruments which necessarily result in average values that are often not relevant for materials and devices where properties vary on the atomic scale. Hence, in order to understand the effects of charge distribution on material properties it is necessary to direct develop methods for imaging charge. This proposal therefore aims to develop experimental approaches to charge imaging using both Scanning Tunneling Microscopy and High Resolution Transmission Electron Microscopy and electron diffraction and to correlate results from these. This program will bring together two research groups at Northwestern University and Oxford University, Great Britain with complementary skills and unique instrumentation: a double aberration-corrected transmission electron microscope in Oxford and an ultra-high vacuum transmission electron microscope at Northwestern as well as the complimentary tool of scanning tunneling microcopy in Oxford. In addition to conventional exchange of information via email and videoconferencing (including the utilization of access grid facilities), there will also be exchange visits by junior scientists and doctoral students. The programs that are developed as part of the collaborative research will be made publicly available.