MRI: Acquisition of a Dual Beam Plasma Focused Ion Beam Scanning Electron Microscope to Accelerate the Materials Characterization

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AbstractNon-technicalThis project uses a new microscope that represents a breakthrough in materials characterization. The new microscope, referred to as a xenon plasma focused ion beam microscope, is being used by the research team to visualize the internal structure and chemical composition of three-dimensional volumes of opaque material with a resolution in the range of nanometers. For the first time, it is possible to measure a large number of structural features in advanced ceramics, high performance alloys, solid oxide fuel cells, and magnetic memory devices. The important contribution is to move beyond isolated observations to a point where we describe materials properties not only in terms of the average or representative internal structure, but also in terms of rare events (large deviations) in the microstructure. The new microscope accelerates research not only at Carnegie Mellon, but also at research institutions and industries in the region. Dozens of graduate and undergraduate students will be trained to use the instrument at Carnegie Mellon. Training for the larger research community is provided through an annual three-dimensional materials science summer school and findings from the instrument are being made available through two web-based repositories: the Three-Dimensional Materials Atlas and the Grain Boundary Data Archive.TechnicalThe xenon plasma focused ion beam microscope deployed in this research has made it possible to both image surfaces and to remove material from the same surfaces in a highly controlled fashion with nano-scale precision, but 50 times faster than with pre-existing instruments. The key to high removal rates is the plasma ion source, which can achieve higher beam currents than the conventional liquid metal sources. This has made it possible to conduct three-dimensional imaging experiments throughout large volumes and conduct site-specific analysis (by transmission electron microscopy or atom probe tomography) of features buried deep within a specimen that are not accessible to conventional liquid metal source microscopes. The project's goals are to prepare samples with specialized geometries for imaging electronic devices under operating conditions by transmission electron microscopy, for high-throughput measurements of grain boundary mobility to study complex ion transitions, for the measurement of the grain boundary character and energy distributions of engineering materials, and for studying the influence of flaw types on stress corrosion cracking in high performance alloys.