Event

Aluminum Electronic Structure and Bonding

in Molecules, Nanoparticles, and Intermetallic Compounds

Stefan G. Minasian

Lawrence Berkeley National Laboratory

Aluminum is the most abundant metal in the Earth’ s crust and an essential component of many scientific and large-scale industrial processes. With steady improvements in aluminum production efficiency and manufacturing methods, usage of aluminum metal is likely to increase further owing to its desirable physical and mechanical properties, low cost, relatively low toxicity, and recyclability. For many applications, aluminum can be regarded as a redox inert, electropositive, Lewis-acidic metal with a formal +3 charge and small ionic radius. However, this simple model has been found inadequate for describing aluminum electronic structure for several energy-related applications. Because the aluminum 3p valence orbitals are directly involved in bonding, measuring aluminum 1s to 3p transitions using aluminum K-edge x-ray absorption spectroscopy could be used to evaluate electronic structure. However, because many synchrotron beamlines are not optimized in the energy regime that includes the aluminum K-edge, previous aluminum K-edge experiments have been limited to studies of aluminum metal, naturally-occurring oxides and minerals, and a handful of synthetic materials.

This talk will describe our approach to develop Al K-edge XAS as a quantitative probe of electronic structure, beginning with a prototypical series of aluminum coordination compounds and ending with discussions of lanthanide and actinide–aluminum intermetallics. The results have had wide-ranging implications, from how we characterize aluminum hydrides used in hydrogen storage schemes to how we understand the mechanisms of electron delocalization in heavy fermion materials.

Inquires please contact Rosa M. Vargas rvargas@sas.upenn.edu