LAUSR

The incorporation of hydrogen normally results in degradation when applied to metals. In this diffraction study, however, improvement of the film structure, such as in-plane grain growth, lattice defect removal and texture enhancement, was observed in a (111)-textured palladium thin film during hydrogen loading and unloading cycles. Accordingly, diffraction stress analysis was performed to investigate the evolution mechanism. It was found that the formation of the β phase during the α-to-β phase transformation occurred at the same in-plane stress present in the α phase, and vice versa. This suggests that the cyclic α–β grain boundary motion during the transformation occurred mainly along the in-plane direction, contributing to the film structure evolution.