Study of some co-precipitated manganite perovskite samples-doped iron

Polycrystalline La0.70Sr0.30Mn1−yFeyO3 (0.05⩽y⩽0.07) samples are prepared by the co-precipitation method and have been studied. The substitution of Mn3+ by Fe3+ reduces the number of available hopping sites for the Mn eg(↑) electron and suppresses the double exchange (DE), resulting in the reduction of the metal–semiconductor transition temperature (TP) and the flux density saturation (Bs). Low-temperature resistivity (ρ) data (below TP) well fit with the relation ρ(T)=ρ0+ρ2T2, indicating the importance of grain/domain boundary effects and electron–electron scattering processes in the conduction of these materials. On the other hand, at high temperature (TPθD/2 the small polaron hopping model is more appropriate than the VRH model.