%0 Conference Paper %B Fifth International Meeting on Electrochromism %D 2002 %T Structural and Electronic Properties of Magnesium-3D Transition Metal Switchable Mirrors %A Baker Farangis %A Ponnusamy Nachimuthu %A Thomas J. Richardson %A Jonathan L. Slack %A Bruno K. Meyer %A Rupert C.C. Perera %A Michael D. Rubin %K EXAFS %K Hydrogen storage materials %K NEXAFS %K thin films %K x-ray diffraction %X

We have observed reversible mirror-to-transparent state switching in a variety of mixed metal thin films containing magnesium and first-row transition elements including Ni, Fe, Co, Mn, and Ti. The very large changes in both reflectance and transmittance on loading these films with hydrogen are accompanied by significant structural and electronic transformations. The valence states and coordination of metal atoms during hydrogen loading were followed using dynamic in situ transmissionmode X-ray absorption spectroscopy. Time-resolved Mg K-edge and Ni, Co, Mn, and Ti L-edge spectra reflect both reversible and irreversible changes in the metal environments. These spectra are compared to those of reference materials and to predictions from calculations.

%B Fifth International Meeting on Electrochromism %C Golden, CO %8 12/2002 %G eng %1

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%2 LBNL-51415 %R 10.1016/j.ssi.2003.08.041 %0 Journal Article %J Journal of Alloys and Compounds %D 2002 %T X-Ray Absorption Spectroscopy of Transition Metal-Magnesium Hydride Thin Films %A Thomas J. Richardson %A Baker Farangis %A Jonathan L. Slack %A Ponnusamy Nachimuthu %A Rupert C.C. Perera %A Nobumichi Tamura %A Michael D. Rubin %K EXAFS %K Hydrogen storage materials %K NEXAFS %K thin films %K x-ray diffraction %X

Mixed metal thin films containing magnesium and a first-row transition element exhibit very large changes in both reflectance and transmittance on exposure to hydrogen gas. Changes in electronic structure and coordination of the magnesium and transition metal atoms during hydrogen absorption were studied using dynamic in situ transmission mode X-ray absorption spectroscopy. Mg K-edge and Ni, Co, and Ti L-edge spectra reflect both reversible and irreversible changes in the metal environments. A significant shift in the nickel L absorption edge shows it to be an active participant in hydride formation. The effect on cobalt and titanium is much less dramatic, suggesting that these metals act primarily as catalysts for formation of magnesium hydride.

%B Journal of Alloys and Compounds %V 356-357 %P 204-207 %8 08/2003 %G eng %1

Windows and Daylighting Group

%2 LBNL-50574 %& 204 %R 10.1016/S0925-8388(02)01237-9