Exploration of polyanionic hydrides Ulrich Häussermann (Arizona State University) DMR 0638826

1. Exploration of polyanionic hydridesUlrich Häussermann (Arizona State University) DMR 0638826 Metal hydrides are considered as potential hydrogen storage materials, but offer additionally many other interesting properties. We initiated a research program on new hydrides of main group metal/semimetal combinations (“polyanionic hydrides”). These hydrides contain hydrogen in unprecedented coordination environments and serve as important model systems for fundamental studies of hydrogen-metal interactions by applying various spectroscopies and computational modeling. The formation of polyanionic hydrides is often accompanied by a metal-nonmetal transition, which can be reversed upon hydrogen desorption. This is a rare phenomenon and interesting for potential application in switchable mirrors for smart windows, antireflection coatings of screens and monitors, etc. The superconducting AlB2-type alloy BaGaGe absorbs hydrogen and forms a semiconducting polyanionic hydride where hydrogen is exclusively attached to Ga. Inelastic neutron scattering spectrum of SrAlSiH exhibiting local Al-H bending and stretching modes. M. H. Lee et al. Inorg. Chem., 46 (2007), 6987-6991. M. H. Lee et al. Inorg. Chem., 47 (2008), 1496-1501. M. J. Evans et al. J. Am. Chem. Soc., 125 (2008) in press.

2. Exploration of polyanionic hydridesUlrich Häussermann (Arizona State University) DMR 0638826 Educational activities Graduate participation: Myeong Lee, Michael Evans, Verina Kranak, Kati Puhakainen. Curriculum development: A new graduate course (“Structure elucidation of solid materials”) was developed to demonstrate how diffraction, spectroscopic and electron microscopy techniques can be combined in modern materials research to extract structural information of a wide range of solids, including disordered, partially ordered and non-crystalline systems. Collaborations and outreach activities Collaborators: Luke Daemon and Thomas Proffen (LANSCE/LANL), Otto Sankey (ASU-Physics), International exchange: Javier Garcia (Augsburg University, Germany) visiting scientist at ASU, Feb-April 2008. Seminars on electron diffraction and high resolution electron microscopy, working with students on structural problems. Lecturer at the LANSCE/LANL summer school “Hydrogen in Materials”, July 12-20, 2007.