TY - CONF T1 - Structural and Electronic Properties of Magnesium-3D Transition Metal Switchable Mirrors T2 - Fifth International Meeting on Electrochromism Y1 - 2002/12// A1 - Baker Farangis A1 - Ponnusamy Nachimuthu A1 - Thomas J. Richardson A1 - Jonathan L. Slack A1 - Bruno K. Meyer A1 - Rupert C.C. Perera A1 - Michael D. Rubin KW - EXAFS KW - Hydrogen storage materials KW - NEXAFS KW - thin films KW - x-ray diffraction AB - 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. JF - Fifth International Meeting on Electrochromism CY - Golden, CO U1 -

Windows and Daylighting Group

U2 - LBNL-51415 DO - 10.1016/j.ssi.2003.08.041 ER - TY - JOUR T1 - X-Ray Absorption Spectroscopy of Transition Metal-Magnesium Hydride Thin Films JF - Journal of Alloys and Compounds Y1 - 2003/08// SP - 204 EP - 207 A1 - Thomas J. Richardson A1 - Baker Farangis A1 - Jonathan L. Slack A1 - Ponnusamy Nachimuthu A1 - Rupert C.C. Perera A1 - Nobumichi Tamura A1 - Michael D. Rubin KW - EXAFS KW - Hydrogen storage materials KW - NEXAFS KW - thin films KW - x-ray diffraction AB - 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. VL - 356-357 U1 -

Windows and Daylighting Group

U2 - LBNL-50574 DO - 10.1016/S0925-8388(02)01237-9 ER -