Fig. 3.

STEM analysis and crystal models of fcc-AuRu₃ NPs. a Low-magnification HAADF-STEM image of the fcc-AuRu₃ NP. b The corresponding FFT pattern of the NP in (a). c The atomic resolution HAADF-STEM image of the red square region in (a). d Model for the atomic arrangement of fcc structure viewed along the [$\overline{1}$10] direction. The unit cell is shown as the red frame. e Model for the atomic arrangement of the hcp structure viewed along the [110] direction. The unit cell is shown as the red frame. f The tomographic reconstruction of the fcc-AuRu₃ NP by EST reconstruction algorithm. g Magnified image of the white square region in (f). h The 0.8 Å-thick slice image of the 3D reconstruction near the centre of the NP. The scale bars in (a), (c), (f), (g) and (h) are 5, 1, 5, 1 and 5 nm