Magnetization processes of polycrystalline La0.7Pb0.3Mn1−xFexO3

A systematic investigation of the magnetic properties in the perovskite materials La0.7Pb0.3Mn1−xFexO3 is presented in this study. The distortion induced by Mn-site substitution is not obvious as radii of Fe and Mn are similar for low Fe-content samples. Powder X-ray diffraction patterns show the same crystallographic phase of rhombohedral symmetry with space group R3¯c for x⩽0.4 and change to orthorhombic symmetry with space group Pnma for x⩾0.6. The zero field cooling–field cooling curves and the values of temperature-dependence magnetization indicate ferromagnetic Mn3+–O2−–Mn4+ double-exchage interaction would be gradually replaced by antiferromagnetic Fe3+–O2−–Mn4+ and Fe3+–O2−–Fe4+ exchange coupling for x=0.6x=0.6 and 0.8 and would be completely replaced by Fe3+–O2−–Fe4+ for x=1.0x=1.0. From the results of experiments, the substitution of Mn by Fe suppresses the double-exchange interaction, weakens the ferromagnetism and consequently decreases the ferromagnetic transition temperature TC and saturation magnetization MS.