The goal of this program is to synthesize intermetallic compounds of the late transition metals that exhibit a wide variety of important physical properties that place them at the forefront of modern science and technology. The project focuses on understanding how intermetallics can be formed using chemical methods that work at much lower temperatures, typically 100 to 550 degrees. This temperature regime (a) is more energy efficient, (b) can form new structures that are not stable at high temperatures, and (c) can provide insight into how the solids form. Because solid-solid diffusion is the rate-limiting step in the synthesis of intermetallic compounds, this project will combine concepts and techniques from solid-state chemistry, solution chemistry, and nanoscience to develop and explore low-temperature synthesis approaches that overcome diffusion problems. This will lead to (a) a diverse toolbox of new chemical reactions, (b) functional new nanomaterials that cannot be made using traditional methods, and (c) an understanding of the formation mechanisms and reactivity of nanocrystalline intermetallics. Graduate and undergraduate students will be trained in both solid-state and solution chemistry techniques as part of this cross-disciplinary project. To integrate research and education, a new research-driven course in inorganic materials chemistry will be developed, and it will contain both classroom and laboratory components and be accessible to graduate and undergraduate students from all materials-relevant science and engineering majors. In addition, a summer fellowship will be established to allow students from traditionally underrepresented groups to participate in this modern solid-state chemistry project.
NON-TECHNICAL EXPLANATION
Technology feeds off of solid-state materials, and the prerequisite to new technologies is the synthesis and creation of new materials. Some of the most important technological materials are intermetallics, which are chemical compounds that form from combinations of metallic elements. These synthetic methods also yield nanometer-size particles, which are important building blocks for creating thin films, composites, and porous materials for possible applications as fuel cells, batteries, and information storage devices. This project provides cross-disciplinary training for undergraduate and graduate students in modern and traditional areas. It also involves the creation of a new materials chemistry course with both classroom and laboratory components, as well as a summer research program focused on providing opportunities to individuals in underrepresented groups. Because of their physical properties, intermetallic nanomaterials are of high interest to industry, and students trained in these areas compete well in the job market.
Intermetallic compounds, which form from the combination of two or more metallic elements, have unique structures and properties that make them important for many current and future technological applications, including permanent magnets, superconductors, shape memory alloys, structural materials, thermoelectrics, hydrogen storage materials, catalysts, and battery materials. When the dimensions of intermetallic crystals are confined to nanometer length scales, their properties and applications can sometimes be expanded and enhanced, opening the door to new materials and possibly new technologies. During this project, we developed new chemical methods for generating a large number of transition metal intermetallic compounds as nanocrystals. Importantly, we focused on understanding how these intermetallic nanocrystals form. By carrying out careful reaction pathway studies, we generated new knowledge that will help scientists to predictably target intermetallic nanocrystals with desired compositions, phases, crystal structures, shapes, and sizes, as future applications demand. We also developed new chemical tools that allow us to manipulate metal and intermetallic nanocrystals, essentially treating them as chemical reagents that can be transformed into other classes of materials using predictable chemical reactions. For example, metal and intermetallic nanocrystals can be converted to metal phosphides, oxides, sulfides, and other intermetallic compounds using relatively simple solution chemistry reactions. In some cases, these techniques allow us to generate new compounds that are not usually accessible using more traditional methods, as well as compounds that had not previously been discovered. Using these new chemical tools, our fundamental new scientific insights into how they work, and the nanoscale materials that they allowed us to generate, we made advances in application areas that include optical (plasmonic) materials, phase change materials, and catalysts that are relevant to fuel cells and industrial chemical production. We anticipate that other application areas will also be impacted by future implementation of the results generated from this project. A diverse group of graduate and undergraduate students contributed to the success of this project, including new Ph.D.’s who have gone onto positions in industry, academia, and national labs and undergraduate students who have transitioned to graduate programs in science and engineering disciplines. Several new undergraduate laboratory modules were created, which add cutting-edge materials applications to the traditional undergraduate education infrastructure. Students supported on this project, along with the PI, were actively involved in outreach initiatives, including demonstrations and laboratory tours for K-12 students, seminars at undergraduate and graduate/research institutions, and local/regional/national technical meetings that targeted a diverse audience. The PI and his students also made research facilities available to undergraduate students from small local colleges that do not have access to such equipment.
