Optical switchable mirrors

Optical Properties of Metal Hydrides Switchable Mirrors I 275... 

The purpose of this article is to review the essential properties of switchable mirror materials with special emphasis on their optical properties. So far three generations of hydrogen-based switchable mirrors have been discovered ... 

Fig. 7.20 The three optical states of a liquid electrolyte Cd-Mg switchable mirror (a) shiny metallic at positive voltage ( 2V), (b) strongly absorbing at 1 V and (c) transparent and insulating at negative voltages (—2V). In this device the Gd-Mg layer deposited on a glass substrate is used as the...

Optical Properties of Meta Hydrides Switchable Mirrors 311... 

Fig. 7.39 Schematic cross-sections and photographs of an all-solid-state switchable mirror [53] in two optical states (a) at negative applied voltage both the CdMgHjf switchable mirror and the WO3 storage electrode are in their transparent state (b) at positive voltage GdMg is metallic and WO3 dark blue.

The evolution of electrical resistivity (p) and optical transmittance (Topt) for red light as a function of hydrogen exposure time for a representative switchable mirror are shown in fig. 1. As the hydrogen concentration increases, there is an initial weak rise in p due to impurity scattering, and there after it decreases steadily until it reaches a minimum in the dihydride phase. At this point, YH2 has a resistivity that is 5 times lower than that of pure Y. At higher H concentrations, p increases by several orders of magnitude and is only limited by the conductivity of the Pd over layer. The optical transmittance remains low until in the dihydride... 

Since its discovery, most of the work on switchable mirror effect has been devoted to the study of hydrogen-induced changes in optical, electronic and structural properties in polycrystalline R metal films, as summarized in the previous section. Though some studies have been reported on single-crystalline films, for example Y films on (110) W substrates (Hayoz et al., 1998) and epitaxial Y films deposited on Nb coated (110) AI2O3 substrates (Wildes et al., 1996 Remhof et al., 1997, 1999), these samples were not suitable for optical and elec-... 

Fig. 53(i) shows a typical example of a regular triangular optical pattern that occur in epitaxial switchable mirrors for a Pd (7 nm) capped Y (400 nm) film imaged in transmitted light while it was slowly deloading from its YH3 a state (Kerssemakers et al., 2000). A dense micrometer-spaced network of opaque lines, defining the domains that are observed to be ei-... 

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