The major theme of the MRSEC research and education programs at the Cornell Center for Materials Research (CCMR) is Mastery of Materials at the Atomic and Molecular Level. The objective is to educate scientists and engineering students (largely PhD students) and postdoctoral researchers in the methods of research used to tackle cutting edge problems in materials research. At the same time CCMR manages and maintains a set of shared experimental facilities that enable this research to be carried out; these facilities are also actively used by a wide spectrum of researchers from across the campus, from other Universities, Government Laboratories and Industry. CCMR also has an expansive and effective educational outreach program that helps students and teachers from primary, secondary and local colleges to learn about materials sciences, recent advances and how to integrate this new knowledge into the classroom. Finally, CCMR's Industrial Partnerships program speeds the transition of new scientific discoveries into technologies that can promote economic growth and opportunities.
Our research is organized into teams focused on several specific topics, including: Controlling Electrons at Interfaces, "Building Blocks" for Photonic Systems, and the Study of the Dynamics of Growth of Complex Materials. CCMR also manages a "Seed Program" that supports smaller short term activities that explore high-risk/high-payoff areas and that integrates new faculty into our interdisciplinary culture. Our long term goal is to control materials systems at or near the level of atomistic precision (atom identity and geometric placement), as is possible in the synthesis of some organic molecules. Our vision is that such control will allow precision tuning of properties and is likely to uncover vast new areas of science, to facilitate the construction of a wide variety of novel devices, and to enable technologies not presently imagined. The proposed research capitalizes on unique science we recently developed, substantially extends the effort in new and ground breaking directions, and explores entirely new topics; all require new talents, new skills and new senior investigators.
The central mission of the Cornell Center for Materials Research (CCMR) was to explore and advance the design, control, and fundamental understanding of materials through collaborative experimental and theoretical studies. The Center focused on forefront problems that required the combined expertise of interdisciplinary research groups (IRGs) of Cornell researchers and external collaborators. The CCMR mission also included K-12 educational outreach; industrial outreach and knowledge transfer; and the operation of shared research facilities. Intellectual Merit Key Achievements The Controlling Electrons at Interfaces IRG made a series of high-impact discoveries that employed single-molecule electrical devices as well-controlled model systems to understand the fundamental nature of electrical conduction. As one example, the ultimate limit in miniaturizing electronics would be to replace today's electrical components — such as resistors and transistors — with individual molecules. Before that can be done, though, scientists need a deeper understanding of how electricity moves through single molecules. To understand this process in exquisite detail, CCMR researchers watched electrons flow through the molecule sketched in Fig. 1 while they slowly pulled on the ends of the molecule. At a particular point during stretching, it became slightly more difficult to pass current through the molecule. Interestingly, this change was not due to broken bonds. (The molecule was not harmed by the experiment.) Instead, the researchers showed that they were subtly changing the magnetic properties of the molecule by making it less symmetric. When the tension was released, the molecule returned to its original state and began passing current more easily. Experiments such as these allow scientists to test their fundamental understanding of how electrons move in molecules. The Atomic Membranes as Molecular Interfaces IRG explored the properties of atomic membranes: mechanically robust, freestanding films of material as thin as a single atom. The group showed that single-atom-thick sheets of graphite — so-called "graphene" films — are truly impermeable (even to helium atoms) and capable of withstanding large pressure differences without leaking, a finding that may enable better chemical barriers and atomically-thin windows. Graphene is also potentially useful for large-area electronics, such as touch screens or solar cells. Unfortunately, graphene grown in the lab is not as conductive as expected. Suspecting that rare defects limit performance, the group developed methods to find and image rare atomic-scale defects. The background image in Fig. 2 might look like a patchwork quilt, but it is actually an electron microscope image of a graphene sheet. Each "patch" (color) is an atomically-precise honeycomb of carbon atoms; however, the patches are rotated with respect to one another. Where two patches with different rotations (different colors) touch — as shown by the inset — the perfect, six-sided honeycombs are stitched together in an imperfect line of five- and seven-member rings. These stitching defects make the film weaker, but not less conductive. The Controlling Complex Electronic Materials IRG pioneered a new route to high-performance materials with tuned magnetic and electronic properties. Computer simulations suggested that an esoteric material, europium titanate, would become quite extraordinary if it were stretched. Since this stretching would shatter the material, the group grew a thin film of europium titanate on top of a second material that had slightly longer chemical bonds, as sketched in Fig. 3. The stretched film was simultaneously ferroelectric and ferromagnetic (multiferroic), with properties over 1000 times better than previously discovered materials. Strong multiferroics could enable advances in many technologies, including high-density hard disks. Broader Impacts Key Achievements The most important outcome was the education of highly trained scientists and engineers who have the skills and drive to be leaders in academia, industry, and government. The research program trained a diverse cadre of graduate and postdoctoral scholars. The Educational Outreach Program established an online lending library of 30+ Cornell-developed, inquiry-based experiments that can be borrowed by any educator in the nation, free of charge (www.ccmr.cornell.edu/education/lendinglibrary/). As an example, Prof. Joel Brock and a local teacher developed the Drop Tube module, shown in Fig. 4, to meet fourth-grade standards. The Industrial Partnerships Program developed the JumpStart program which partnered small businesses with Cornell faculty to solve well-defined technical problems. The JumpStart Program was instrumental in bringing innovative products to market. Instruments in the CCMR Shared Facilities were used by over 700 academic and industrial users annually. For example, GM researchers used the world-leading UltraSTEM (scanning transmission electron microscope) to study fuel-cell catalysts. The gray-scale image in Fig. 5 is a GM catalyst as seen in a standard electron microscope. But is the catalyst conventional platinum or something more interesting? The researchers zoomed in on two catalyst particles and asked the UltraSTEM to show the cobalt atoms in red and the platinum atoms in green, revealing the chemical structure of the particles as a cobalt "core" coated with a platinum "shell." This is one example of NSF investments benefitting both universities and industry.
