Figure 1. (A) BF-TEM ex situ images of as received alumina nanospheres with the diameter of the particle of measured as of 50 ± 26 nm (inset) (n = 132).

Here the aggregation of nanoparticles is likely induced by the solvent evaporation during the TEM sample preparation. Inset shows particles size distribution. Scale bar: 50 nm. (B) A thin deposit on a surface of neighboring nanoparticles can be seen at higher magnification. Scale bar: 20 nm.