Switchable mirrors have so far been made of rare-earth and rare-earth-magnesium based metal-hydrides. In this investigation we study Mg-Ni-hydrides, which have been shown by Richardson et al. to exhibit switchable properties similar to those of the rare-earth hydrides. Cyclic voltammetry on MgzNiHx samples with 0.8 < z < 3.7 shows that addition of one Mg atom per Mg2Ni gives the best ab/desorption kinetics for hydrogen. X-ray diffraction reveals a structural change as hydrogen is absorbed. The metal-insulator transition is confirmed with simultaneous resistivity measurements. A pressure-composition isotherm of Mg2NiHx is also determined electrochemically. Optical spectrometry during gas loading gives an optical band gap of 1.6 eV for Mg2NiH4. This gap increases with increasing Mg content in a way similar to that of the Mg-doped rare-earth hydrides.
Electrochromism of Mg-Ni hydride switchable mirrors / J. Isidorsson, I.A.M.E. Giebels, M. Di Vece, R. Griessen - In: Solar and Switching Materials / [a cura di] C.M. Lampert, C.-G. Granqvist, K.L. Lewis. - [s.l] : International Society for Optical Engineering, 2001. - ISBN 0819441724. - pp. 128-137 (( convegno Solar and Switching Materials tenutosi a San Diego nel 2001.
Electrochromism of Mg-Ni hydride switchable mirrors
M. Di VecePenultimo
;
2001
Abstract
Switchable mirrors have so far been made of rare-earth and rare-earth-magnesium based metal-hydrides. In this investigation we study Mg-Ni-hydrides, which have been shown by Richardson et al. to exhibit switchable properties similar to those of the rare-earth hydrides. Cyclic voltammetry on MgzNiHx samples with 0.8 < z < 3.7 shows that addition of one Mg atom per Mg2Ni gives the best ab/desorption kinetics for hydrogen. X-ray diffraction reveals a structural change as hydrogen is absorbed. The metal-insulator transition is confirmed with simultaneous resistivity measurements. A pressure-composition isotherm of Mg2NiHx is also determined electrochemically. Optical spectrometry during gas loading gives an optical band gap of 1.6 eV for Mg2NiH4. This gap increases with increasing Mg content in a way similar to that of the Mg-doped rare-earth hydrides.Pubblicazioni consigliate
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