Acquisition of a multi-purpose powder diffractometer for the X-ray facility at ASU Chemistry for use in research and education

Arizona State University, Scottsdale AZ

Investigators

Abstract

With this award from the Chemistry Research Instrumentation and Facilities: Multi User program (CRIF:MU), the Department of Chemistry at Arizona State University will acquire a multi-purpose powder diffractometer for the X-ray facility. This diffractometer will be used for research and education in the study of (1) semiconductor metal hydrides and in fundamental studies of metal/semimetal-hydrogen interactions and their consequences to chemical structures and physical properties, (2) mechanisms of carbon dioxide mineral sequestration which are important for the development of economically viable low pressure sequestration processes, (3) the study of complicated phase relations and structural chemistry of silicates at the boundary between the Earth?s upper and lower mantle, (4) the role of minerals in the enrichment and distribution of metal trace elements in biofilms, sediments and soils, (5) the synthesis of structure-property relationships of ferromagnetic metals, and (6) nucleation and growth events in glass materials important for a general understanding of the physical chemistry of glasses and for manufacturing ceramics with special properties. The X-ray diffractometer allows accurate and precise measurements of the three dimensional structure of a molecule, including bond distances and angles, and it provides accurate information about the spatial arrangement of the molecule relative to the neighboring molecules. The synthesis of materials having an extended structure, such as polymers, inorganic solids, glasses, or gels, often yields a polycrystalline or phase-impure powder. Powder X-ray diffraction (Powder XRD) is the most powerful tool available for the structural characterization of such products. Powder XRD pattern can elucidate the structure and relative abundance of the crystalline phases present, it can expose the existence of preferred crystalline orientation (called texture) of a film of a material relative to a crystalline substrate surface, and the XRD linewidth can provide an estimate of the mean crystallite (or grain) diameter. In addition, the structure of extremely thin films (<100 nm) of materials can be investigated by powder-XRD whereas such films cannot be probed by single-crystal XRD. These studies will have an impact in a number of areas, especially synthetic chemistry.