Fivefold annealing twin in nanocrystalline Au/Pd film

Abstract In this study, we report the experimental observation of five-fold annealing twin in the nanocrystalline Au/Pd thin film without external stress by annealing the film for 20 min at 473 K using atomic-resolution high angle annular dark field (HAADF) scanning transmission electron microscopy (STEM) imaging, and energy dispersive X-ray spectroscopy (EDS) employing Cs aberration-corrected electron microscopy. As per the knowledge of the authors, this is the first time that five-fold annealing twin has been observed for Au/Pd thin films. Furthermore, the spectroscopic elemental analysis shows the uniform distribution of palladium in the film, indicating no palladium grain boundary segregation. Strain analyses have been performed by geometric phase analysis (GPA) across the five-fold structures. GPA method shows the non-uniform strain distribution across the various segments of the five-fold structure.