Surface morphology and switchable optical properties of Pd/Y films during gas hydrogen absorption/desorption process

The surface morphology and optical properties of the Pd/Y films prepared by magnetron-sputtering were observed and measured. Pd/Y films are of planar structure and the Pd cover layer on Y films is of nano-sized island structure. During gas hydrogen absorption/desorption process, YH3 and YH2 hydrides formed at the contacting sites of Pd particles with Y grains under catalysis of Pd. During the process of hydrogen absorbing, YH3 hydride formed. The transmission ratio of the films increases with increasing of hydrogenation time and light wavelength, the absorption limitation occurs at lambda=400 nm due to the gap of ferbidden band of yttrium. During the hydrogen desorbing, YH3 hydride dissociates and transforms to YH2 hydride, the transmission ratio reaches to maximum at lambda=689 nm.