Structural, optical and electronic properties of LaMgHx switchable mirrors

Structural, optical and electronic properties of lanthanum magnesium alloy thin films are studied in situ in real time during hydrogenation. X-ray dat a show that the as-deposited films contain the intermetallic phase LaMg wit h CsCl structure as well as fee beta -La and fee LaHx. Hydrogenation initia tes a transformation of beta -La to beta -LaHx, while the intermetallic pha se disproportionates. The fee structure stays intact during further uptake of hydrogen up to LaH3, and Mg transforms to the rutile structure of MgH2. During hydrogen absorption the alloys change from a good conducting, metall ic state with high reflectance, to a transparent color neutral insulator wi th a band-gap of about 3 eV. (C) 2001 Elsevier Science Ltd. All rights rese rved.