Thin switchable mirrors

The growth and microstmcture of switchable mirror thin fllrns involves specific aspects that need to be discussed before describing their physical properties. We focus first on Y, La and rare-earth films (for convenience all abbreviated as RE films), deposited in both their metallic and hydride forms. Some references to second-generation mirrors (Mg-RE) are included and third-generation switchable mirrors (Mg-TM) are shortly discussed separately. 

One of the most important aspects of the discovery of switchable mirrors is the fact that in the form of thin films rare-earth hydrides (REH ) are amenable to a whole series of experiments, which were often impossible with bulk samples since hydrogen absorption resulted in a total disintegration of bulk samples. 

Only at 300 MPa is hep SCH3 formed [244]. Giebels et al. [179] confirmed the formation of SCH3 recently in thin films of Mg-Sc. These films become very transparent when the Mg content is larger than 65 at.%. They behave as Mg-Y and Mg-La switchable mirrors, that is they show a black state and a shift of the band gap with excess Mg. As Sc is a very expensive material, successful attempts have been made to substitute it with Ti, V and Cr [246]. 

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