Hydrogen, the lightest element, has a unique flexibility to combine with other elements, especially metals. The aim of this project is to investigate a new family of main group metal hydrides, termed polyanionic hydrides, which exhibit novel coordination environments and bonding situations for hydrogen. Polyanionic hydrides provide a unique opportunity for fundamental studies of hydrogen-metal interactions by spectroscopic and computational methods, and also bear a high potential for interesting materials properties, for example for hydrogen storage and other applications areas. The project provides broad training for graduate and undergraduate students through the manifold of experimental and computational techniques involved. The training of students is especially directed toward multidisciplinary research, which is further emphasized by collaborations with national facilities for neutron diffraction and spectroscopy. Multidisciplinary and cooperative research is at the heart of much of today's materials science, both in industry and at universities, and is a key to meeting the rapidly increasing demand of society for materials with new or improved properties.
Hydrogen is nature's simplest and most abundant element. It is considered as a clean fuel in the envisioned hydrogen economy. At the same time hydrogen displays a unique flexibility to interact with other elements. For example, it reacts explosively with oxygen to yield water, it leads to catastrophic embrittlement when accidentally incorporated into steel and many other materials, it passes readily through foils made of palladium, and it can be reversibly included in specific alloy systems and then driven out. The latter phenomenon is of high interest for storing hydrogen in a safe way for mobile applications, like cars. However, progress toward a practical hydrogen storage material has been slow and the hydrogen storage challenge is a serious bottleneck toward a hydrogen economy. Better materials for more practical hydrogen storage systems can only be made with an improved understanding of how hydrogen interacts with other elements and especially metals. Graduate and undergraduate students involved in this research will work with the most advanced experimental and computational techniques. For measuring the location and movement of hydrogen atoms, materials have to be exposed to a flux of neutrons. These experiments will be done at national laboratories, such as Los Alamos. The training of students is especially directed toward multidisciplinary research, which is at the heart of today's materials science efforts, both in industry and at universities, and a key to meeting the rapidly increasing demand of society for materials with new or improved properties.
Hydrogen is nature's simplest - because lightest - and most abundant element. It is considered as a clean fuel in the envisioned hydrogen economy. At the same time hydrogen displays a unique flexibility to interact with other elements. For example, it reacts explosively with oxygen to water, it leads to catastrophic embrittlements when accidentally incorporated in steel and many other materials, it passes readily through foils made of palladium, and it can be reversibly included in specific alloy systems and driven out. The latter phenomenon is of high interest for storing hydrogen in a safe way for mobile applications, like automobiles. In this research project we could show that hydrogen incorporation in metal/semimetal systems can lead to additional phenomena, like metal-semiconductor transitions. We also found how new synthesis methods exploiting extremely high hydrogen pressures can lead to materials with extraordinary high hydrogen contents. Such "hydrogen-dominant" materials have exciting structures, stretching common wisdom of chemical bonding, while at the same time revealing interesting properties, as for instance superconductivity. The project provided broad training for graduate and undergraduate students through the manifold of experimental and computational techniques involved. In this respect an important experience was provided by the neutron scattering center at Los Alamos National Laboratories. Neutrons are elementary particles that interact with hydrogen in a special way, so the location and motion of hydrogen in materials becomes visible to researchers. At Los Alamos neutrons are produced in a so-called spallation source and made available for research. Students working on this project traveled frequently to Los Alamos for various measurements and collaborated closely with the instrument scientists. Multidisciplinary and cooperative research is at the heart of today's materials science, both in industry and at universities, and a key to meet the rapidly increasing demand of society for materials with new or improved properties.
