Photochromic Properties of Yttrium Oxyhydride Powders Derived from Magnetron‐Sputtered Thin Films

Photochromic yttrium oxyhydride (YHO) materials have potential applications in energy‐saving smart windows and optical sensors. In this study, YHO powders are prepared from thin films deposited on flexible substrates using reactive magnetron sputtering. X‐ray diffraction data show that the YHO powder exhibits a smaller lattice constant compared to the YHO thin film. The photochromic performance of YHO powders is investigated through time‐dependent optical reflection measurements. Results indicate that the initial phase of the photodarkening and bleaching processes in YHO powder is dominated by a fast time constant, followed by a slow time constant that governs the subsequent phase. Additionally, the photodarkening and bleaching characteristics can be tuned by varying the synthesis parameters for YHO powders.