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Figure 4
Ga–Pd nanocatalysts revealed by annular dark-field (ADF) imaging in aberration-corrected STEM. (a) Low magnification ADF image of the Ga–Pd nanoparticles. (b)–(d) GaPd2 along the [010] zone axis. (b) Atomically resolved ADF image (low-pass filtered) on which the structure of GaPd2 in the [010] projection is overlaid. The orthorhombic unit cell is outlined in red, and two `f.c.c.-like' units by dashed black lines. (c) A selected region (bi) from (b) over which the thickness of the nanoparticle is sufficiently constant to enable a relative comparison of the intensities of the atomic columns in the image. A portion of the GaPd2 structure in [010] projection is overlaid in (d), confirming that the lower and higher intensity atomic columns in the image correspond to those in the [010] projection of GaPd2 that exclusively contain Ga or Pd respectively. (e)–(h) Small Ga–d nanoparticle morphologies (scale bars: 1 nm). (e) Evidence of `distorted-f.c.c.-like' nanocrystalline structure characteristic of Ga–Pd in the intermetallic state. (f) Twinned truncated octahedral nanoparticle exhibiting pseudo-{111}f.c.c. re-entrant facets and surface defects. An oxidic disordered over-layer (DO) decorating the surface of the nanoparticle is indicated. (g) Decahedral and (h) icosahedral fivefold twinned morphologies viewed down their five- and twofold symmetry axes, respectively. Reproduced with permission from Leary et al. (2013BB36).

IUCrJ
Volume 1| Part 6| October 2014| Pages 530-539
ISSN: 2052-2525
doi:10.1107/S2052252514020818