Materials MicroCharacterization Collaboratory
This last goal is by all measures, the most difficult task of this proposal. It is a straightforward process to connect instrumentation together by a serial cables and/or networks and achieve some measure of remote operation of scientific instrumentation. However, to do materials science research in a new way it will be necessary to connect groups of scientists together in a virtual laboratory setting which provides the stimulus and technology to collectively observe, and attack problems using combinations of ideas, methodologies and instrumentation which does not exist at any single location. It will be this, namely the personal interactions facilitated by the Collaboratory, which is the true test of success of the Collaboratory.
We propose to develop our collaboratory research around the topic areas "Interfaces and Surfaces", which are critical in controlling the properties and behavior of a wide variety of materials. We will concentrate specifically on studies of metal/oxide interfaces, such as are important for corrosion protection (e.g. adherent oxide films on alloys), and studies of the behavior of fine metal particles on substrates, such as are important in catalyst systems (e.g. noble metals on oxide supports for reducing emissions from diesel exhausts). The Collaboratory will interact with appropriate outside users and utilize the materials and expertise which they bring to bear on the conduct of the research. An example collaboration in each research area will suffice to illustrate how our Collaboratory will function. In catalyst research, ORNL would use the (presently on-line) field emission TEM to study changes in structure due to gas reactions at elevated temperatures. ANL would use the advanced AEM (also on-line) to characterize distribution of the ultra-fine noble metals by high-angle annular dark field imaging and electron spectroscopy. LBNL would perform hot-stage experiments in their on-line high voltage TEM, to study model specimens of noble metals on oxide films to provide fundamental information on the behavior of metal clusters at high temperatures. The information developed will contribute to a full understanding of the mechanisms of catalyst poisoning and de-activation. All of these experiments could be followed (and even run) live-time by the participating collaboratory scientists and users.
In studies of interfaces between advanced high temperature metallic and intermetallic materials and their protective oxide layers, the formation of protective oxides is highly dependent on the nature of elemental segregation to the oxide/metal and oxide/oxide interfaces. High spatial resolution analytical techniques are required to examine the segregation behavior; in situ techniques provide important insight into evolution of the microstructure. These experiments would be conducted so as to provide complementary results from several sites in an interactive environment. It is also important to measure the residual stresses in the same materials whose microstructure has been extensively characterized, which can be done in collaborations between microscopy facilities and the x-ray and neutron beamline facilities.
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