Comment on "Magnetoresistance and phase composition of La-Sn-Mn-O systems"

In a published paper by Li et al. [Phys. Rev. B 60, 10284 (1999)] the transport properties and phase composition of the manganites La1-xSnxTMnO3+delta (x = 0.1-0.5) are studied: The authors analyze their results assuming the existence of two phases: a perovskite LaMnO3+delta and a pyrochlore (La0.5Sn0.5)(2)Mn2O7. We consider that they misinterpret the x-ray diffraction data and we conclude that the manganites La1-xSnxMnO3+delta are in fact a multiphase material composed by LaMnO3+delta, La2Sn2O7, Mn3O4 and SnO2. The magnetic transition observed by Mossbauer experiments around 65 K attributed by Li et nl. to that of the (La0.5Sn0.5)(2)Mn2O7 pyrochlore phase would correspond to that of the paramagnetic-ferrimagnetic one of Fe-doped Mn3O4.