Improved optical properties of switchable mirrors based on Pd/Mg-TiO2 films fabricated by magnetron sputtering

For the past two decades, the reported magnesium-based gasochromic switchable mirrors have been limited to magnesium alloys. Herein, inspired by the excellent catalytic property of TiO2 for the magnesium hydrogen reaction, the novel gasochromic switchable mirrors based on Pd/Mg-TiO2 films were fabricated by magnetron sputtering and their optical properties, microstructures and structure-function relationship were investigated in this study. The results show that the mirror based on Pd/0.9Mg-0.1TiO(2) film exhibits larger optical dynamic range at visible wavelengths and excellent structural recovery even after 100 cycles of hydrogenation and dehydrogenation compared with Pd/Mg film. The brookite TiO2, crystalline Mg and some amorphous phases coexist in the Mg-TiO2 layer of Pd/0.9Mg-0.1TiO(2) film with no trace of Pd. Interestingly, the TiO2 nanocrystal clusters are distributed in stripe among Mg matrix. In contrast, the Pd/0.63Mg-0.37TiO(2) film consists of crystalline Mg and MgTi2O5 phase, where MgTi2O5 phase is derived from the reaction of superfluous TiO2 with a part of Mg and deteriorates the optical properties of the mirror dramatically. In summary, this work offers a novel strategy for improving optical performance of Mg-based switchable mirrors by introducing metal oxides into switchable layer and uncovers a broad field to be explored. (C) 2018 Elsevier Ltd. All rights reserved.