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DS: Dünne Schichten
DS 21: Schichteigenschaften IV
DS 21.2: Talk
Thursday, March 29, 2001, 09:45–10:00, S 13/14
Mechanical properties and the kinetics of switching in gasochromic films — •Tom Pedersen, Christoph Liesch, Hansjörg Weis, Christian Salinga, and Matthias Wuttig — I. Physikalisches Institut, RWTH Aachen, 52056 Aachen, Germany
Switchable coatings are of interest because of their potential applications as smart window coatings, in display technology and as a gas sensor. For a number of gasochromic switchable coatings, simultaneous measurements of reflection, transmission and stress have been carried out in-situ during switching. The measurements of mechanical stresses are important as they yield information on the elastic and/or plastic deformations of the films. They also enable the calculation of the volume change involved in the switching process, as well as supplying additional information important for the understanding of the switching processes. The materials examined include WOx, GdHx, and MgHx. It is found that the mechanical stresses arising in the three films upon H incorporation are of quiet different magnitude, leading to plastic deformations and short lifetimes in some cases and to elastic behaviour and long lifetimes in others. In the case of GdHx and MgHx irreversible changes of the films have been found, whilst the processes in the WOx films have been found to be reversible. The switching kinetics have been simulated by different models resulting in a better understanding of the mechanisms involved.