In situ atomic force microscopy observation of hydrogen absorption/desorption by Palladium thin film

► The surface morphology of a Pd thin film during hydrogen absorption and desorption was observed using in situ AFM. ► Residual stress in the film was compressive for the as-sputtered film, but changed to tensile after a hydrogen absorption/desorption cycle. ► Hydrogen absorption of the film induced irreversible grain agglomeration. ► These results indicate that residual tensile stress after an absorption/desorption cycle develops because of irreversible grain agglomeration.