%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 Applied Physics Letters %D 2001 %T Switchable Mirrors Based on Nickel-Magnesium Films %A Thomas J. Richardson %A Jonathan L. Slack %A Robert D. Armitage %A Robert Kostecki %A Baker Farangis %A Michael D. Rubin %X

An electrochromic mirror electrode based on reversible uptake of hydrogen in nickel magnesium alloy films is reported. Thin, magnesium-rich Ni-Mg films prepared on glass substrates by cosputtering from Ni and Mg targets are mirror-like in appearance and have low visible transmittance. Upon exposure to hydrogen gas or on cathodic polarization in alkaline electrolyte, the films take up hydrogen and become transparent. When hydrogen is removed, the mirror properties are recovered. The transition is believed to result from reversible formation of Mg2NiH4 and MgH2. A thin overlayer of palladium was found to enhance the kinetics of hydrogen insertion and extraction, and to protect the metal surface against oxidation.

%B Applied Physics Letters %V 78 %P 3047-3049 %8 05/2001 %G eng %N 20 %1

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%2 LBNL-47180 %& 3047 %R 10.1063/1.1371959