Magnetic Resonance Studies of Solids

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9403667 Conradi Magic-angle spinning of metal-deuterides will yield separate, resolved nuclear magnetic resonance (NMR) lines for Deuterium atoms at inequivalent sites. This technique will be used to understand the site occupation in metallic alloys and compounds, to assist in the development of improved materials for hydrogen fuel storage and electrochemical cells. The anomalous relaxation in many metal-hydrides at high temperatures may arise from rapid gas-solid exchange of hydrogen molecules. Argon overpressures can reduce the gas-phase relaxation and thereby test this mechanism, specifically in the face centered cubic dihydrides. Nanocomposites are a new class of high strength, though materials made by compaction of extremely small (e.g. 20 nm) grains, sometimes in a more ductile matrix. To understand their unusual properties, NMR will probe the crucial interfaces. Specifically, NMR will determine the interfacial area on an atomic scale and the nature of core-cladding bonding. Techniques will be developed for detection, measurement, and manipulation of unusually broad resonances. Applications will include double-resonance distance determinations in biological systems between Nitrogen fourteen and Carbon thirteen. % % % % Metal hydrides are attractive candidates for clean energy technologies, for hydrogen fuel storage and electrical batteries. The location of Hydrogen (or Deuterium) atoms in the structures will be determined by applying magic-angle spinning nuclear magnetic magnetic resonance to deuterided metallic alloys and compounds. The results will direct the development of improved hydrogen storage materials. At high temperatures, many metals- hydrides exhibit an unexplained mechanism of spin-relaxation. One suggestion is that rapid exchange between the gas and solid occurs; more exotic explanations have also been proposed. The role of hydrogen in the unexplained relaxation will be tested. Nanocomposites are a new class of high stre ngth, tough materials made by compaction of extremely small (20 nm) grains, often in more ductile matrix. The interfaces grain are crucial to the mechanical properties. Nuclear magnetic resonance (NMR) will be used to measure the interfacial area on an atomic scale and to determine the nature of the core-cladding bond. Techniques will be developed for the detection, measurement and manipulation of very broad NMR lines, which otherwise unusable. Applications to biological structures and the detection of Nitrogen (e.g. in explosives) will be pursued. ***