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- H 2

Novel metal hydrides by high pressure synthesis Ulrich Häussermann, Arizona State University, DMR 0638826.

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- H 2

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  1. Novel metal hydrides by high pressure synthesisUlrich Häussermann, Arizona State University, DMR 0638826 Metal hydrides are considered as potential hydrogen storage materials, but offer in addition many other interesting properties. The application of high (hydrogen) pressures allows access to new and novel “hydrogen-dominant” materials that have chemical compositions and/or crystal structures not accessible by conventional synthesis techniques. We facilitated gigapascal hydrogenations in multi-anvil high pressure devices by developing large volume cell assemblies and by indentifying ammonia borane, BH3NH3, as a superior internal hydrogen source. “Hydrogen-dominant” materials may now be synthesized in gram quantities thus allowing comprehensive characterization of their structural, chemical, and physical properties. This includes especially the application of neutron diffraction and spectroscopy. BH3NH3 - H2 h-BN Top: Temperature dependent Raman spectra of ammonia borane, BH3NH3, at 1 GPa and photographs of the sample in the diamond anvil cell (middle panel). At around 129 oC the evolution of dihydrogen is seen as dark droplets. Thermolysis under pressure releases irreversibly almost the entire hydrogen content of the molecule in two distinct steps. Bottom: Hydraulic press (1000 t capacity) at the high pressure facility at ASU used for compressing multi-anvil cell assemblies. The crystal structure of Li2PtH6 obtained at 8.0 GPa from a mixture LiH-Pt-BH3NH3. H coordinates Pt(IV) octahedrally, however, octahedra approach each other closely, giving rise to a perovskite-like H substructure. In contrast, PtH6 octahedra in low pressure synthesized Cs2PtH6 are well separated.

  2. Novel metal hydrides by high pressure synthesisUlrich Häussermann, Arizona State University, DMR 0638826 Collaborations and outreach activities Collaborators: Luke Daemon and Thomas Proffen (LANSCE/LANL), Otto Sankey (ASU-Physics), Javier Garcia (Augsburg University, Germany). One particular outreach activity is our partnership with ASU’s “Science is fun” program (run by the Center of Solid State Sciences). The program is directed to K-12 schools in the greater Phoenix area and reaches more than 15,000 students per year. Science demonstrations on various topics and levels of complexity are brought to classrooms. Demonstrations are constantly developed, tested, improved and rearranged. Demonstration (“the components of air”) performed together with “Science is fun” coordinator Roxanna Montoya at Sunridge School, Mesa, AZ (May 2010). Outside temperatures approached 100 F. Sure, l-N2 was needed as an important ingredient! About 60 children (grades1-3) learned about oxygen, nitrogen, noble gases and CO2, but also man-made pollutants in the air.

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