Comment on ‘Low-temperature synthesis of α-Fe2O3 nanoparticles with a closed cage structure’ by X. Wang et al. [Chem. Phys. Lett. 384 (2004) 391]

A Letter by Wang et al. reported synthesis of α-Fe2O3 nanoparticles with a closed cage structure. The authors mistook thickness fringes in the transmission electron micrographs (TEM) as evidence for ‘layers’ of ‘a closed cage structure’. We prepared α-Fe2O3 nanoparticles using procedures described by Wang and recorded a series of TEM images of the particles at 0.5° increments in specimen tilt angle. In this Letter, we first explain the origin of thickness fringes, and then present a series of images to prove that these particles do not have a closed cage structure.