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.