Comment on “The magnetic properties of nanosized La1 − x Ca x MnO3 (0.5 ≤ x ≤ 0.8)”

Some data on the dc and ac magnetic properties of electron-doped La1 − xCaxMnO3 (LCMO, 0.5 ≤ x ≤ 0.8) sol–gel prepared nanoparticles with mean particle size of ~50 nm have been reported in a recent article (Liu et al. J Nanopart Res 13:2305, 2011). In particular, it is claimed that the charge ordering (CO) transition, which is observed in the bulks, disappears completely, and the ferromagnetic (FM) one occurs in all the samples studied. The authors also attributed the enhanced FM state with relatively large values of spontaneous magnetization in their samples to the good connection among the adjacent particles. It is suggested in the comment through the present article that such claims seem to be doubtful, and a natural reason for the above noted effects may be the systematic shift of a real composition (Ca-doping level) from its nominal value due to, e.g., oxygen non-stoichiometry of the considered samples. The numerous uncertainties and obscurities are also characteristic of the article being commented upon.