Fig. 2: Scanning transmission electron micrographs of U-magnetite samples.
From: Nanoscale mechanism of UO2 formation through uranium reduction by magnetite
High-angle annular dark-field scanning transmission electron microscopy images of U-magnetite samples were obtained (scale bar 5 nm). a, b 4-h Sample; c: replicate 4-h sample; d–f 12-h sample; g–i 24-h sample. i Energy-dispersive X-ray spectroscopy showing U in green and Fe in magenta. The bright contrast spots on the magnetite surface in a–h are U atoms. Arrows in a and b point to dispersed U atoms on the surface of magnetite nanoparticles or accumulated U atoms on the edge of magnetite nanoparticles; arrows in c point to formed U nanoparticles in a replicate 4-h sample (see Fast Fourier Transform in Fig. 3); arrows in d and f point to formed U nanoparticles on or near the surface of magnetite nanoparticles; the arrow in e points to the accumulation of U atoms along planes in the same orientations as magnetite lattice planes; arrows in h point to individual nanoparticles in a single nanowire that extends from the magnetite surface; inserted image in g simulated UO2 pattern (in green) for the three nanoparticles contained in the observed nanowire structure and the defined zone axes: from top to bottom, nanoparticles are in the [011], [112], and [001] zone axis. The simulation of the given zone axis of U atoms in green was done using Vesta50.
