Cycling durability of switchable mirrors

The remarkable optical properties of switchable mirrors, i.e. the ability o f lanthanide-magnesium films to switch reversibly between reflecting and tr ansparent states by changing the hydrogen concentration, are interesting fo r several applications. Since for any application a high cycling durability is necessary, we have studied the durability of various, differently prepa red, switchable mirrors. As a model system we have chosen to switch in a 1 M KOH solution. Typical degeneration Features that were found included slow er kinetics, oxidation and delamination upon cycling of the switchable mirr or. Of the various attempts to improve the cycle lifetime: we obtained the best results by using a switchable mirror loaded with hydrogen during depos ition. (C) 2001 Elsevier Science Ltd. All rights reserved.